J-PARC, KEK & JAEA, Ibaraki-ken
The Japan Proton Accelerator Research Complex (J-PARC) is a multi-purpose facility making full use of secondary particles like neutrons, muons, Kaons, and neutrinos produced by the MW-class proton accelerators. The J-PARC accelerator scheme inserts a 3-GeV Rapid-Cycling Synchrotron (RCS) in between a 400-MeV injector linac (at present 181 MeV) and a several-ten GeV Main Ring (MR). The RCS has already demonstrated extraction of one pulse of 2.6·1013 protons at 3 GeV, which corresponds to 315 kW if operated at 25 Hz, with a beam loss less than one percent, and a beam power of 210 kW for a period of 70 sec in September. The beam circulation and RF capture in MR have been done in May. Also, the neutron production target was beam-commissioned, providing high-resolution, high-efficiency neutrons. The RCS users’ run and the 30-GeV MR acceleration are planned in December. Rationale for the J-PARC accelerator scheme will be resumed on the basis of the results and difficulties encountered during the development, the construction and the commissioning. The upgrade plan, and, hopefully, some experimental results will be presented.
SLAC, Menlo Park, California
Funding: Work supported by US DOE contract DE-AC03-76SF00515.
Second-generation B-Factory proposals are being considered both by KEK in Japan (Super KEKB) and by an INFN Frascati/SLAC/CalTech collaboration in Italy (Super-B). Novel collision schemes like crab waist with crab-sextupoles and also crab cavities are being proposed to mitigate the beam-beam effects of a large crossing angle. The talk will present concepts from both proposals in the context of the experience with the present PEP-II and KEKB B-Factories, which have been successful far beyond the initial performance goals.
IHEP Beijing, Beijing
BEPCII is major upgrades of BEPC (Beijing Electron-Positron Collider). It is a double ring e±e collider as well as a synchrotron radiation (SR) source with its outer ring, or SR ring. As a collider, BEPCII operates in the beam energy region of 1-2.1 GeV with design luminosity of 1*1033cm-2s-1 at 1.89 GeV. As a light source, the SR ring operates at 2.5 GeV and 250 mA. Construction of the project started in the beginning of 2004. Installation of the storage ring components completed in October 2007. The BESIII detector was moved to the Interaction Region (IR) on May 6, 2008. In accordance to the progress of construction, the beam commissioning of BEPCII is carried out in 3 phases: Phase 1, with conventional magnets instead of the superconducting insertion magnets (SIM’s)n in the IR; Phase 2, with SIM’s in the IR; Phase 3, joint commissioning with the detector. The maximum luminosity reached to 2.3*1032cm-2s-1. This paper summarizes progress of the construction and commissioning in 3 phases, while focusing on the third phase.
* On behalf of the BEPCII Team
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) is a third-generation storage-ring-based x-ray source that has been operating for more than 11 years and is enjoying a long period of stable, reliable operation. While APS is presently providing state-of-the-art performance to its large user community, we must clearly plan for improvements and upgrades to stay at the forefront scientifically. Significant improvements should be possible through upgrades of beamline optics, detectors, and end-station equipment, along with local, evolutionary changes to the storage ring itself. However, major accelerator upgrades are also being investigated. One very promising option that has been the subject of considerable research is the use of an energy recovery linac. In this option, APS would transition from a source based on a stored electron beam to one based on a continuously generated high-brightness electron beam from a linac. Such a source promises dramatically improved brightness and transverse coherence compared to third-generation storage rings, as well as distinctly different temporal properties.
RIKEN Nishina Center, Wako
The RIKEN RI Beam Factory (RIBF) is pushing the limits of energy for heavy ion cyclotrons. The first experiment of the RIBF has successfully finished with the discovery of new isotopes 125Pd and 126Pd* in June 2007 with a 345-MeV/nucleon uranium beam. However, the total transmission efficiency was limited to be less than 1%. In addition, a carry-over of oil was found in the refrigerator of the Superconducting Ring Cyclotron (SRC), which was the main accelerator of the RIBF. To solve these problems, we have improved beam monitors, upgraded the oil remover system of the compressor of the liquid helium cryogenic plant at SRC and made a series of acceleration tests. As a result, 0.3 pnA of a 345-MeV/nucleon uranium beam was stably delivered to RIBF users in November 2008 and a 345-MeV/nucleon 48Ca beam with the intensity of 170 pnA was obtained in December 2008. In the PAC09 presentation, we will summarize our operating experience with the SRC and developments of RIBF accelerators in addition to most up-to-date performance of the RIBF accelerator complex.
*T. Ohnishi et al., J. Phys. Soc. Jpn. 77 (2008) 083201
NSCL, East Lansing, Michigan
The 2007 Long Range Plan for Nuclear Science had as one of its highest recommendations the “construction of a Facility for Rare Isotope Beams (FRIB) a world-leading facility for the study of nuclear structure, reactions, and astrophysics. Experiments with the new isotopes produced at FRIB will lead to a comprehensive description of nuclei, elucidate the origin of the elements in the cosmos, provide an understanding of matter in the crust of neutron stars, and establish the scientific foundation for innovative applications of nuclear science to society.” A heavy-ion driver linac will be used to provide stable beams of >200 MeV/u at beam powers up to 400 kW that will be used to produce rare isotopes. Experiments can be done with rare isotope beams at velocities similar to the driver linac beam, at near zero velocities after stopping in a gas cell, or at intermediate (0.3 to 10 MeV/u) velocities through reacceleration. An overview of the design proposed for implementation on the campus of Michigan State University leveraging the existing infrastructure will be presented.
INFN/LNL, Legnaro (PD)
The speaker will have expertise in the design, construction and operation of RFQs, both normal and superconducting. This talk will focus mostly on recent developments in RFQs for high power proton and deuteron beams, for both scientific and diverse purposes (e.g. Radioactive Nuclear Beam facilities, long-term irradiation tests of materials for Thermonuclear Fusion Reactors). The experience of the group at LNL in the field of cw RFQs originates from the realization of the PIAVE RFQ (superconducting 585 keV/u, heavy ion A/q<8.5) and the construction of the TRASCO RFQ (5 MeV, 30 mA protons). More recently within the collaboration between Europe and Japan for the construction of IFMIF-EVEDA in Rokkasho, the group at LNL is in charge of the design and construction of the RFQ (130 mA deuteron, 5 MeV). The physics design and the first construction test results will be ready for the PAC conference in 2009. In the same talk, the design approaches and experimental results of cw RFQs under development (for lower beam power) by other groups in Europe could be reviewed.
CLASSE, Ithaca, New York
Fermilab, Batavia
Cornell University is planning to build an Energy-Recovery Linac (ERL) X-ray facility. In this ERL design, a 5 GeV superconducting linear accelerator extends the CESR ring which is currently used for the Cornell High Energy Synchrotron Source (CHESS). Here we describe some of the recent developments for this ERL, including linear and nonlinear optics, tracking studies, vacuum system design, gas and intra beam scattering computations, and collimator and radiation shielding calculations based on this optics, undulator developments, optimization of X-ray beams by electron beam manipulation, technical design of ERL cavities and cryomodules, and preparation of the accelerator site.
ORNL, Oak Ridge, Tennessee
Solid-state based high-power modulators utilize new technology, yet must meet the operational needs of a high reliability facility. This modulator technology is in use at SNS, and is under consideration and development for future machines, such as the ILC and PEFP. Through operational experience and a sustained development effort, a number of improvements have been deployed in the SNS modulator system to meet the high availability demands of operating facilities. The operating experience and development effort of the world-wide community will also be reviewed.
KEK, Ibaraki
Tigold, Chiba 289-1226
KFG, NEUSS
KYOCERA Corporation, Higashiomi-city, Shiga
MELCO SC, Tsukuba
Nichicon (Kusatsu) Corporation, Shiga
The KEK Linac delivers the beam to KEK-Photon factory storage ring, KEKB ring and the advanced ring for photon factory. In order to deliver the beam to the KEK-photon factory and KEKB ring simultaneously, the pulsed bending magnet was installed at the end of KEKB Linac. The pulsed bending magnet extract 2.5GeV electron beam to the PF beam transfer line. The deflection angle of the magnet is 0.114 radians and the field strength is almost 1.22T. The peak current stability is better than 0.1% at 24kA operation. The maximum repetition rate is 25Hz. The 1.2m long ceramic chamber is inserted into the 1m long magnet. This system makes possible the top up operation of PF ring.
KEK, Ibaraki
KEKB linac is a 600 m long electron linac and is used to deliver beam to four rings, KEKB HER ring (electron, 8 GeV), KEKB LER ring (positron, 3.5 GeV),PF ring (electron, 2.5 GeV) and PF-AR ring (electron, 6.5 GeV). KEKB rings are operated under top-up injection mode and have occupied the current linac operation mostly. Simultaneous injection to three rings (KEKB HER and KEKB LER and PF) is required due to the top-up injection to PF ring is required recently. We have developed the pulsed bending magnet for this. This magnet produces 114 mrad deflection angle for 2.5 GeV PF beam. The fast switching between KEKB and PF can be performed up to 25 Hz. We will describe this magnet system in detail.
USP/LAL, Sao Paulo
Funding: FAPESP, CNPq
The IFUSP Microtron transport line guides the 5 MeV electron beam from the booster to the main microtron, where it can be accelerated up to 38 MeV in steps of 0.9 MeV. A few meters after leaving the main microtron, the beam is guided to the experimental hall, which is located 2.7 m below the accelerator room. The beam leveling is made by two 90° bending magnets. In the experimental hall there is a switching magnet to drive the beam to two different experimental lines. Each of these lines has another 90° bending magnet. These magnets were designed, constructed and characterized. In this work we present the analysis of the field distribution of these 90° bending magnets. Comparison between field simulation and data from field mapping is presented. We also present a reproducibility analysis where the field distributions of two twin magnets are presented.
Sigmaphi, Vannes
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The paper presents the magnetic measurements of the 32 long dipoles and 8 short dipoles magnet manufactured by Sigmaphi for the ALBA synchrotron booster based in Spain. An extensive set of measurements based on search coils was made by Sigmaphi to characterize the magnetic field at different currents. This paper describes the magnetic measurements results. The measurements show the maximum field integral deviation between the magnets is within ± 3.10-3 as expected.
Fermilab, Batavia
Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359
An R&D proton linac is under construction at FNAL and it will use solenoid lenses in the beam transport line. Because the needed focusing field is on the level of 6 Tesla, superconducting systems are used. In the low energy part of the linac, which uses room temperature accelerating structures, the lenses are placed in stand-alone cryostats. Production of the lenses and cryostats for the low energy section is under way. In the superconducting accelerating sections, the lenses are mounted inside RF cryomodules. Although focusing solenoids for the high energy sections have been designed and prototypes tested, R&D is still ongoing to address magnetic shielding and alignment issues. This report summarizes the performance of lenses for the low-energy part of the linac and presents the status of ongoing R&D.
CLASSE, Ithaca, New York
Funding: Work supported by National Science Foundation under contract DMR 0225180
The paper describes the design as well as short prototype and the prototype test result of undulator magnet planned for use in Cornell Energy Recovery Linac. The prototype has pure permanent magnet (PPM) structure with 24mm period, 5mm diameter round gap and is 30cm long. In comparison with conventional undulator magnets it has: a) full X-ray polarization control; b) 40% stronger magnetic field in linear and approximately 2 times stronger in circular polarization modes; c) compactness. These advantages were achieved through a number of non-conventional approaches. Among them is control of the magnetic field strength via longitudinal motion of the magnet arrays. The moving mechanism is also used for x-ray polarization control. The compactness is achieved using a recently developed permanent magnet soldering technique for fastening PM blocks. We call this device a "Delta" undulator after the shape of it's PM blocks.
CERN, Geneva
The Compact LInear Collider, under study, requires vacuum chambers with a very small aperture, of the order of 8 mm in diameter, and with a length up to around 2 m for the main beam quadrupoles. To keep the very tight geometrical tolerances on the quadrupoles, no bake out is allowed. The main issue is to reach UHV conditions (typically 10-9 mbar static pressure) in a system where the vacuum performance is driven by water outgassing. For this application, a thin-walled stainless steel vacuum chamber with two ante chambers equipped with NEG strips, is proposed. The mechanical design, especially the stability analysis, is shown. The key technologies of the prototype fabrication are given. Vacuum tests have been carried out on the prototypes. The test set-up as well as the performance of the pumping system are presented and compared with predictions.
BNL, Upton, Long Island, New York
Kyushu University, Hakozaki
IAP, Frankfurt am Main
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A new heavy ion preinjector, consisting of an Electron Beam Ion Source (EBIS), an RFQ, and IH Linac, is under construction at Brookhaven National Laboratory. This preinjector will provide ions of any species at an energy of 2 MeV/u, resulting in increased capabilities for the Relativistic Heavy Ion Collider, and the NASA Space Radiation Laboratory programs. Initial operation of the EBIS and RFQ will be reported on, along with the status of the construction and installation of the remainder of the preinjector.
BNL, Upton, Long Island, New York
The low energy (35 keV) and medium energy (750 keV) transport lines for (un)polarized H- have been reconfigured to reduce beam losses and the beam emittance out of the 200 MeV Linac. The medium energy line in the original layout was 7 m long, and had ten quadrupoles, two beam choppers, and three bunchers. The bunchers were necessary to keep the beam bunched at the entrance of the Linac. About 35% beam loss occurred, and the emittance growth was several fold. In the new layout, the 750 keV line is only 0.7 m long, with three quads and one buncher. To preserve beam polarization in the 35 keV line, the solenoid in front of the RFQ (35 keV to 750 keV) was replaced with an Einzel lens. To reduce the spin-precession in the LEBT, which may cause the depolarization, a 47.4 degree bend was removed and focusing solenoid in front of RFQ was replaced with an Einzel lens. We will present the experimental result of the upgrade.
ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The concept of an ultra-low transverse emittance injector operating in CW mode for an XFELO* was discussed at LINAC-08**. Here we will report the design optimization of the injector, which includes a 100 MHz RF-gun with thermionic cathode, an energy filter to produce short bunches (~0.5 nsec), a velocity bunching section, higher harmonic cavities to minimize longitudinal emittance, two bunch compressors and accelerating sections operating at 400 MHz and 1300 MHz to obtain 540 MeV electrons. The proposed design is capable of producing 40 pC bunches with 0.5 psec rms time width and 0.7 MeV rms energy spread. Most significantly, the transverse rms emittance is kept below 0.11 π μm. The longitudinal emittance and bunch time width can be substantially reduced for low-charge bunches of several pC.
*K.-J. Kim, Y. Shvyd’ko, and S. Reiche, Phys. Rev. Lett., 100 244802 (2008).
**P.N. Ostroumov, K.-J. Kim, Ph. Piot, Proceedings of the Linac-2008.
ENEA C.R. Frascati, Frascati (Roma)
INFN/LNF, Frascati (Roma)
Rome University La Sapienza, Roma
LBNL, Berkeley, California
The SPARX X-FEL accelerator will be the first FEL facility to operate with a hybrid (RF plus magnetic chicane) compression scheme. Numerical studies of propagation of beam density modulations stemming from photogun laser, through the photoinjector operating under velocity bunching conditions have been carried out. A semi-analytical model for the linear gain in a RF compressor is also being developed and some preliminary results are presented.
Sokendai, Ibaraki
KEK, Ibaraki
RISE, Tokyo
Kyoto University, Kyoto
At Accelerator Test Facility (ATF), we have developed and successfully used RF Photocathode gun as the source of electrons. We have also used a similar gun in the Laser Undulator Compact X-ray source facility (LUCX), KEK (High Energy Accelerator Research Organization) for performing experiments to generate X-rays by inverse Compton scattering. Both the existing guns have mode separation of 4 MHz. We designed a new RF Gun with high mode separation of around 9 MHz and high Q value to achieve a low emittance beam of good quality. We are also modifying the power delivery scheme to the accelerator at LUCX to achieve the acceleration of 200 nC in 100 bunches with low emittance. This will help to increase the intensity of X-rays by the inverse Compton scattering.
KEK, Ibaraki
The first operation of the positron production with a tungsten single-crystal target has been performed at the positron source of the KEKB injector linac for the KEK B-factory (KEKB) from September 2006 to June 2007 (~10 months). Previously we carried out the systematic studies on the positron-production efficiencies with tungsten crystals having various thickness using 4- and 8-GeV electron beams at the test beam line during the term of 2000-2005. Finally, we optimized the thickness of the tungsten crystal at 4 GeV and developed both the target fabrication technique and the crystal-axis alignment technique in 2006. After the systematic studies, we installed a tungsten crystal target at the KEKB positron source without any significant modifications for the positron source. The data on the positron production, especially, the positron-production efficiencies and stabilities in terms of the primary electron and positron beams, were obtained during the nominal KEKB operation in this term. We summarize the long-term operational performance on the positron production with the tungsten crystal target at the KEKB injector linac in this report.
INFN/LNF, Frascati (Roma)
UCLA, Los Angeles, California
Istituto Nazionale di Fisica Nucleare, Milano
INFN-Roma II, Roma
ENEA C.R. Frascati, Frascati (Roma)
University of Tehran, Tehran
INFN-Roma, Roma
One of the main goals of the SPARC high brightness photoinjector is the experimental demonstration of the emittance compensation process while compressing the beam with the velocity bunching technique, also named RF compressor. For this reason, the first two S-band travelling wave accelerating structures downstream of the RF gun are embedded in a long solenoid, in order to control the space charge induced emittace oscillations during the compression process. An RF deflecting cavity placed at the exit of the third accelerating structure allows bunch length measurements with a resolution of 50 μm. During the current SPARC run a parametric experimental study of the velocity bunching technique has been performed. The beam bunch length and projected emittance have been measured at 120 MeV as a function of the injection phase in the first linac, and for different solenoid field values. In this paper we describe the experimental layout and the results obtained thus far. Comparisons with simulations are also reported.
LBNL, Berkeley, California
Funding: This work was supported by the Office of Science, U. S. Department of Energy, under Contract No. DE-AC02-05CH11231.
The Advanced Photoinjector Experiment (APEX) seeks to validate the design of a proposed high-brightness, normal conducting RF photoinjector gun and bunching cavity feeding a superconducting RF linac to produce nC-scale electron bunches with sub-micron normalized emittances at MHz-scale repetition rates. The beamline design seeks to optimize the slice-averaged 6D brightness of the beam prior to injection into a high gradient linac for further manipulation and delivery to an FEL undulator. Details of the proposed beamline layout and electron beam dynamics studies are presented.
SLAC, Menlo Park, California
Funding: Supported by US DOE under contract DE-AC03-76SF00515.
The Stanford Synchrotron Radiation Laboratory operates a thermionic radio-frequency gun as part of its injector for the SPEAR 3 storage ring. In order to generate the high bunch charge required for top-off injection, it may be advantageous to operate the thermionic cathode as a photo-emitter. In this note we report on measurements of the wavelength dependence of the quantum efficiency of a tungsten dispenser cathode in a low-field environment, and on high-power tests of the injector in photoemission mode.
TRIUMF, Vancouver
DAE/VECC, Calcutta
TRIUMF (Canada) and VECC (India) are planning to each build a 1.3GHz 50MeV/500kW superconducting electron linac as a driver for producing radioactive ion beams through photo-fission. The two institutes have launched a collaboration with the initial goal to design, build and test a 5-10MeV superconducting injector cryomodule capable of accelerating up to 10mA. A testing area is being set-up at TRIUMF to house the electron gun, rf buncher, injector cryomodule, diagnostic station and beam-dump for beam studies. The project will test all critical elements of the final linac; beam halo generation, HOM excitation, LLRF and rf beam loading and cavity and cryomodule design/performance. The scope and status of the project will be described.
CEA, Gif-sur-Yvette
With the aim of producing an intense flux of 14 MeV neutrons, the International Fusion Materials Irradiation Facility (IFMIF) relies on two high power CW accelerator drivers, each delivering a 125 mA deuteron beam at 40 MeV to a common lithium target. The Engineering Validation and Engineering Design Activities (EVEDA) phase of IFMIF, which has been launched in the middle of 2007, has two major objectives: to produce the detailed design of the entire IFMIF facility and to build and test the key systems, in particular the prototype of a high-intensity CW deuteron accelerator (125 mA @ 9 MeV). The design of the IFMIF accelerator, as well as the design of the prototype to be installed in Rokkasho (Japan) are presented.
IPN, Orsay
INFN/LASA, Segrate (MI)
SCK-CEN, Mol
CEA, Gif-sur-Yvette
IAP, Frankfurt am Main
An Accelerator Driven System (ADS) for transmutation of nuclear waste typically requires a 600 MeV - 1 GeV accelerator delivering a proton flux of a few mA for demonstrators, and a few tens of mA for large industrial systems. Such a machine belongs to the category of the high-power proton accelerators, with an additional requirement for exceptional "reliability": because of the induced thermal stress to the subcritical core, the number of unwanted "beam-trips" should not exceed a few per year, a specification that is far above usual performance. This paper describes the reference solution adopted for such a machine, based on a so-called "fault-tolerant" linear superconducting accelerator, and presents the status of the associated R&D. This work is performed within the 6th Framework Program EC project "EUROTRANS".
Fermilab, Batavia
Funding: Work supported by US DOE under Contract No. DE-AC02-07CH11359
CHEF is body of software dedicated to accelerator beam dynamics and optics computations. It consists in a hierarchical set of libraries and a standalone application based on the latter. The code makes extensive use of templates and modern idioms such as smart pointers and generalized function objects. CHEF has been described in contributions at past conferences. In this paper, we document and discuss the implementation of recent improvements including:
- use of embedded SQL database technology to store, organize and retrieve lattice function data,
- a general approach to "knobs" based on generalized function objects,
- an improved architecture to support runtime plug-in propagation physics,
- a basic space-charge kick element,
- a facility to record particle loss on aperture boundaries and
- support for the MADX input format.
ANL, Argonne
Several high power proton and ion linac projects based on superconducting accelerating technology are currently under study and drive an important worldwide R&D effort on superconducting cavities, especially for low and medium energy linacs. Multi-cell elliptical cavities, single or multi-spoke cavities, half-wave and quarter-wave superconducting cavities have been developed at many laboratories and institutions and continue to extend the state-of-the-art for this class of cavities. This talk reviews recent developments and results for SC cavity performance along with a brief overview of associated components such as mechanical slow tuning systems, fast tuners and rf power couplers.
JLAB, Newport News, Virginia
A major portion of the ILC R&D effort is focused on increasing the sustainable gradients in the baseline TESLA-shape SC cavities. This is a world-wide effort with major contributions from DESY (in parallel with their XFEL program), JLAB, FNAL and KEK. During the past year, the work in the US and Japan has ramped up considerably, and PAC09 is an opportune time to review the contributions from the groups in these regions, as well as at DESY.
GANIL, Caen
Solid state rf amplifiers are being considered for an increasing number of accelerator applications, both circular and linear. Their capabilities extend from a few kW to several hundred kW, and from less than 100 MHz to above 1 GHz, for operation both in the linear and saturated regime. This talk will review the state of the art and future prospects of rf power amplifiers for accelerator applications.
IHEP Beijing, Beijing
KEK, Ibaraki
TIPC, BeiJing
Funding: Supported by National Natural Science Foundation of China (10525525)
1.3 GHz single cell large grain (LG) cavities have been studied in our research programs on the superconducting cavity for the International Linear Collider (ILC) in the last three years and five LG cavities were fabricated at IHEP and KEK. Three cavities were dealt with by surface treatments based on electro polishing (EP) and the maximum gradient of 47.90 MV/m was achieved. The other two cavities were treated based on chemical polishing (CP) and both reached the accelerating gradients higher than 35 MV/m with the maximum gradient of 40.27 MV/m. In this paper, the performance comparison of the large grain cavities will be presented and discussed.
ANL, Argonne
Funding: Work supported by U.S.Department of Energy, Office of Science, Office of Basic Energy Science, under Contract No. DE-AC02-06CH 11357
Recently, a new SLED test stand located in the Advanced Phone Source linac klystron gallery was developed using a spare modulator-klystron system and a recently developed prototype water station. The new test stand will be used to condition, tune and perform rf measurements on spare SLEDs without interfering with normal daily linac operations. This will allow technical groups to replace a low-performance SLED from one of the operational linac sectors with a fully conditioned SLED. The pre-conditioned SLED is expected to require less conditioning time after being put into operation compared to an unconditioned SLED. As an additional benefit, the prototype water station system developed to replace aging linac water systems can be tested under realistic conditions. In this paper, we describe the test stand design, prototype water station system, and first results using it to condition SLEDs and perform SLED rf measurements.
IHEP Beijing, Beijing
In the conventional 324 MHz DTL designed for China Spallation Neutron Source (CSNS) accelerating H- ion from 3MeV to 132MeV, there are 7 tanks and currently the R&D of tank-1 is under proceeding, which has 29 cells and 29 quadrupoles. In design, the Tank-1 has a tilt field distributed partially in order to obtain most effective energy gain and low Kilpatric parameter. In order to decrease the difficulty of tuning the partial tilt field distribution, a new analysis named transfer matrix method is introduced. Verifying of the calculation and simulation of the transfer matrix has been finished with MDTFISH code, picking parameters from CSNS and SNS. Checking the method on the model tank in CSNS will be operated.
UMAN, Manchester
Here we present initial results on an alternate design for CLIC main accelerating linacs which is moderately damped and detuned structure. In order to suppress the wake-fields, we detune the lowest dipole modes as they have significant impact on the beam emittance compared to the other multipoles. In order to mitigate the reappearance of the wake-field of a detuned accelerator structure, we provide moderate damping by coupling cells to manifolds which run parallel to each accelerator structure. The manifolds are designed such that they are non-propagating at the acceleration mode frequency. The cell parameters are optimised by considering the r.f. breakdown, pulse surface heating and beam dynamics constraints.
Far-Tech, Inc., San Diego, California
We describe a novel acceleration structure for acceleration of electron and ion beams where the cell-to-cell coupling is provided by slot resonances in the wall of adjacent accelerator cells. As with the side-coupled linac, the concept allows for the operation of a standing-wave structure in a phase and amplitude stabilized pi/2 mode. We explore the applications of such a structure to electron and ion accelerators.
IAP, Frankfurt am Main
A short RFQ prototype was built for tests of high power RFQ structures. We will study thermal effects and determine critical points of the design. Simulations with CST Microwave Studio and first measurements were done. First results and the status of the project will be presented.
CEA, Gif-sur-Yvette
GANIL, Caen
LPSC, Grenoble
The Spiral2 project at Ganil aims at producing exotic ion beams for Nuclear Physics. The accelerator of the primary beam is a superconducting LINAC designed to provide 5mA deuteron beams at 40MeV. It will also allow accelerating stable ions of different Q/A values ranging from protons to Q/A=1/6 heavy ions. The accelerator should be commissioned by the end of 2011, first beam in 2012; the first tests aiming to produce exotic beams are planned one year later. The superconducting LINAC consists of 12 low beta (0.07) quarter wave (88MHz) superconducting (SC) cavities and 24 beta (0,14) SC cavities integrated in their cryomodule. The status of the low beta cryomodules, supplied by the CEA Saclay Irfu institute, is reported in this paper. The RF full power tests were performed at the end of 2008 on the qualifying cryomodule, and the tests of the first series cavity in vertical cryostat were performed during spring 2009.
CLASSE, Ithaca, New York
Funding: Work supported by NSF Grant PHY 0131508
The RF power required to phase-stabilize the Cornell University ERL main linac cavities is expected to be driven by microphonic-noise. To reduce the required RF power we are exploring the possibility of active compensation of cavity microphonic noise with the cavities in the Cornell ERL injector cryomodule. The Cornell ERL injector cryomodule houses five elliptical 2-cell SRF cavities developed for the acceleration of a high current (100mA) ultra-low emittance beam and is currently undergoing extensive testing and commissioning. Each of the five cavities is equipped with a blade tuner; each blade tuner integrates 4 piezoelectric actuators and vibration sensors for the active compensation of cavity detuning. This paper presents first results of active frequency-stabilization experiments performed with the Cornell ERL injector cryomodule cavities and their integral blade/piezoelectric fast tuners.
CLASSE, Ithaca, New York
Funding: Work Supported by the NSF and DOE
Superconducting RF cavity quench detection is presently a cumbersome procedure requiring two or more expensive cold tests. One cold test identifies the cell-pair involved via quench field measurements in several 1.3 GHz TM010 pass-band modes. A second test follows with numerous fixed thermometers attached to the culprit cell-pair to identify the particular cell. A third measurement with many localized thermometers is necessary to zoom in on the quench spot. We report here on a far more efficient alternative method which utilizes a few (e.g. 8) oscillating superleak transducers (OST) to detect the He-II second sound wave driven by the defect induced quench. Results characterizing defect location with He-II second sound wave OST detection, powering multiple modes of the 1.3GHz TM010 passband to locate multiple defects, and corroborating measurements with carbon thermometers will be presented.
CLASSE, Ithaca, New York
Fermilab, Batavia
Funding: Work Supported by the U.S. Department of Energy
To build the ~14,000 cavities required for the ILC each of the three world regions must have a sizable industrial base of qualified companies to draw cavities from. One of these companies, Niowave Inc., recently manufactured six 1.3 GHz single-cell cavities for qualification purposes. All six cavities achieved gradients above 25 MV/m before they were limited by the available RF power (Q-slope) or quenched. This paper will report the results of cold tests for all six cavities and on the causes of quench determined by 2nd sound detection and optical inspection.
Cornell University, Ithaca, New York
Funding: This work is supported by the National Science Foundation.
Cornell University is developing an Energy-Recovery-Linac driven x-ray light source. One of the major components of this accelerator will be its 5 GeV superconducting main linac. The design of the superconducting RF cavities in this main linac has been optimized primarily for two objectives: (1) low RF losses from the accelerating mode to minimize refrigeration cost and (2) strong Higher-Order-Mode damping to preserve low emittance and prevent beam break-up at high beam current (100 mA). In this paper we study the robustness of this optimized cavity design with respect to small cell shape fluctuations from fabrication errors.
CLASSE, Ithaca, New York
Funding: National Science Foundation
Diagnosing field-limiting behavior in multi-cell superconducting cavities can be difficult due to the lack of direct local measurements of cavity surface properties. The results of multiple vertical tests on several 5-cell vertically electropolished 1.3GHz superconducting cavities with measurements of cavity surface properties are presented. A combination of oscillating superleak transducer and resistive thermometry data for various accelerating passband modes are used to infer the field-limiting mechanism for several cells of each multi-cell cavity.
CLASSE, Ithaca, New York
Funding: DOE
The first phase of the Cornell Energy Recovery Linac was the high current, low emittance injector. At present the injector is under commissioning. The next phase calls for the development of multicell cavity for the main linac. The cavities need to have low RF losses to minimize refrigeration and strong HOM damping to preserve low emittance and prevent beam break-up at high current (100 mA). Here we present the RF design of the cavity meeting these requirements.
Fermilab, Batavia
Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359
The Fermilab High Intensity Neutrino Source (HINS) Linac R&D program is building a 60 MeV superconducting H- linac. The Linac incorporates SC solenoids, high power RF vector modulators and SC spoke-type accelerating cavities starting at 10 MeV. This will be the first application and demonstration of any of these technologies in a low-energy, high-intensity proton/H- linac. The HINS effort is relevant to a high intensity, SC H- linac that might serve the next generation of neutrino physics and muon storage ring/collider experiments. Three types of superconducting resonators are used in the linac front end. Single Spoke Resonators typs-1 (SSR1) at Beta=0.2, Single Spoke Resonators type-2 (SSR2) at Beta=0.4 and Triple Spoke Resonators (TSR) at Beta=0.6. In this paper we describe the Buffer Chemical Polishing (BCP) performed on SSR1-#2 and the results of the cold tests for this bare cavity. We also describe the inelastic tune performed on cavity SSR1-#1, during this operation we measured also the spring constant and the frequency sensitivity of the end walls. We have also completed the design for the helium vessel that will be used to jacket SSR1 resonators and we present its design here.
Fermilab, Batavia
Different couplers are described that allow the reduction of both transverse wake potential and RF kick in the SC acceleration structure of ILC. A simple rotation of the couplers reducing the RF kick and transverse wake kick is discussed for both the main linac and bunch compressors, along with possible limitations of this method. Designs of a coupler unit are presented which preserve axial symmetry of the structure, and provide reduced both the RF kick and transverse wake field.
Fermilab, Batavia
MIPT, Dolgoprudniy, Moscow Region
Long 11-cell, beta=0.81 L-band structure is considered as an initial stage of the high-energy part of the Project-X in order to accommodate to a standard CM4 cryomodule. The cavity shape is optimized for maximal energy gain providing the same time field flatness along the structure not worse than for ILC beta=1 cavity, and the same ratio of surface magnetic field to electric field. The results of spectrum analysis for monopole and dipole HOMs is presented as well as the HOM damper design.
FZJ, Jülich
Forschungszentrum Jülich GmbH, Institut fur Nuklearchemie (INC), Jülich
The paper describes the design, fabrication and first test results of the triple-spoke cavity (resonant frequency 352 MHz, beta=0.48) developed at Forschungszentrum Jülich in the frame of High Intensity Pulsed Proton Injector project. The cavity has 5 cm diameter beam aperture, a transverse radius of 21.7 cm and the whole length of 78 cm. An initial wall thickness of niobium sheets used for cavity fabrication was around 4 mm. The RF cavity design has been adapted to two main goals - the simplest technology of cavity manufacture and for the prime goal of the project to achieve the best possible structural parameters (Lorenz force frequency shift and a resonant frequency pressure dependence). Intense cavity structural analyses have been conducted and the further prospectives on cavity developments are also presented. Construction of the niobium cavity prototype has been completed, the cavity has been chemically processed. Results of initial cold test are discussed.
FZJ, Jülich
CEA, Gif-sur-Yvette
The driver of the International Fusion Material Irradiation Facility (IFMIF) consists of two 125 mA, 40 MeV cw deutron accelerators. A superconducting option for the 5 to 40 MeV linac is based on Half-Wave Resonators (HWR) has been choosen. The first cryomudule should contain 8 HWR's with resonant frequency of 175 MHz and beta=v/c=0.094. The paper describes RF design of half-wave length resonator. The requirents on high power coupler define its installation in the cavity central region. Few options of cavity tune were investigated, the capacitive tuner installed opposite to the coupler port have been accepted. The cavity structural analyses have been conducted and cavity stiffening has been worked out.
HRC, Santa Clara, California
Funding: Work performed under the auspices of the U.S. Department of Energy SBIR Grant No. DE-FG02-08ER85197.
The salient features and design parameters of a dual resonant ring system configured for evaluating the high gradient performance of 11.424 GHz TW linear accelerator structures are presented; and the inherent rapid protection mechanism that automatically limits energy deposition during breakdown of the structure, and minimizes RF source reflections, is discussed. The diagnostic characteristics of the RF bridge load monitors and their unique capability of detecting the power imbalance caused by a feedback loop phase change of less than 2 parts in 10000, representing a 2 to 3 degree phase change of the linac structure, is described. The transient and steady-state power apportionment within the ring system is analyzed; and, in considering initial high power tests using an 18-cavity CLIC/KEK/SLAC structure, the results indicate that the demonstration of an unloaded average accelerating gradient of 108 MV/m will require a source power of 26 MW.
LANL, Los Alamos, New Mexico
The LANSCE linac RF system consists of four 201.25 MHz RF stations that supply RF power to the drift tube linac(DTL), and forty-four 805 MHz RF stations, that supply RF power to the coupled-cavity linac(CCL). There are four large high voltage power supplies for the DTL RF systems. Seven high voltage power supplies provide the power for the 805 MHz klystrons. All power supplies consist of a transformer/rectifier, Inductrol Voltage Regulator (IVR) and a capacitor bank with crowbar protection. After 39 years of operation, some components are approaching the end of life and will be refurbished through the LANSCE-R project to ensure the reliability of the machine until 2025. An analysis of the oil in the high voltage power supply units was done to assess their health to determine if units need to be replaced or repaired as part of LANSCE-R. Since 1998 the oil in each unit has been sampled and tested annually, and reprocessed when required. Gas-in-oil data for these units from 1998 to present was analyzed. The levels of each gas component, trends in the data and the significance of the each dissolved gas are discussed. The health of the units is assessed.
ORNL, Oak Ridge, Tennessee
ORNL RAD, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The SNS has been operational and delivering beam to the target for 3 years. Over this time period we have increased the beam power delivered to the target to 700 kW, 50% of the design goal. The RF Group has acquired a fair amount of experience in the operation and maintenance of our RF systems during the power ramp up process. This paper reviews the design and layout of the various SNS RF systems, documents the present state and performance of the systems and covers, in a broad sense, issues raised during operation and improvements we have undertaken as well as future RF system requirements.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
ALICE (Accelerators and Lasers in Combined Experiments) incorporates two super-conducting radio frequency (SCRF) cryomodules each with two identical 9-cell cavities that are powered by 5 inductive output tubes (IOTs) from 3 different commercial suppliers. During the commissioning of the ALICE rf system numerous problems were encountered with the operation of the high voltage power supply and the auxiliary power supplies, which had to be resolved before the beam commissioning of the accelerator could commence. The issues encountered and measures taken to improve the operation of the rf system are described within this paper.
ELETTRA, Basovizza
Funding: The work was supported in part by the Italian Ministry of University and Research under grant FIRB-RBAP045JF2
The former linac sections used in the injector system of the Elettra Laboratory storage ring will be upgraded for use on the FERMI@elettra project, a free-electron laser user facility operating down to 3 nm. These seven accelerating sections are 3π/4 mode backward-travelling wave (BTW) constant-impedance structures, powered by 45 MW TH2132A klystrons couple to what was called a PEN – power enhancement network, or more commonly referred to as a SLED system. Due to breakdown problems inside the sections, that was the result of high peak fields generated during conventional SLED operation, the sections experienced difficulties in reaching the design gradients. To lower the peak field and make the compressed pulse “flatter”, phase-modulation of the SLED drive power option is investigated. This paper presents the results of this investigations and includes a detailed mathematically analysis.
RIKEN/SPring-8, Hyogo
JASRI/SPring-8, Hyogo-ken
We report the high power rf test results of C-band accelerator system for X-ray free electron laser (XFEL) in SPring-8. The C-band accelerator system is composed of two C-band accelerator of Choke-mode-type HOM damping structure, the rf pulse compressor, the 50 MW klystron, oil-filled modulator and solid state switching high voltage charger. It is designed to operate at rather high accelerating gradient as high as 35 MV/m, therefore it is crucial to evaluate high gradient performance and reject some component with defect or poor performance. In the 8 GeV main accelerator, 64 C-band systems will be used in total, whose components are under mass production at several industries in Japan. Some of these systems have been installed and tested in high-power test bunker since July 2008. We report on statistics of the high voltage breakdown, and related measurement; such as power calibration of klystron 50 MW, gain measurement on rf pulse compressor.
BNL, Upton, Long Island, New York
The NSLS II is a state of the art 3 GeV synchrotron light source being developed at BNL. The injection system will consist of a 200 MeV linac and a 3GeVbooster synchrotron. The transport lines between the linac and booster (LtB) and the booster and storage ring (BtS) must satify a number of requirements. In addition to transporting the beam while mantaining the beam emittance, these lines must allow for commissioning, provide appropriate diagnostics, allow for the appropriate safety devices and and in the case of the BtS line, provide for a stable beam for top off injection. Appropriate diagnostics are also necessary in the linac and booster to complement the measurements in the transfer lines. In this paper we discuss the design of the transfer lines for the NSLSII along with the incorporated diagnostics and safety systems. Necessary diagnostics in the linac and booster are also discussed.
CLASSE, Ithaca, New York
Funding: Funding support from the National Science Foundation
X-ray beam production from a linac beam is investigated, especially emphasizing the optical matching flexibility that is possible with an external beam but not with a storage ring. Compared to existing storage ring light sources, a high energy linac (with or without recirculation) can produce monochromatic hard x-ray beams having comparable flux density, and far higher brilliance, than are available with existing storage rings. Full coherence and the possibility of diffraction limited focusing are preserved by avoiding the need for x-ray focusing mirrors.
Diamond, Oxfordshire
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
STFC/RAL, Chilton, Didcot, Oxon
Imperial College of Science and Technology, Department of Physics, London
USTRAT/SUPA, Glasgow
UMAN, Manchester
The New Light Source (NLS) project was launched in April 2008 by the UK Science and Technology Facilities Council (STFC) to consider the scientific case and develop a conceptual design for a possible next generation light source based on a combination of advanced conventional laser and free-electron laser sources. Following a series of workshops and a period of scientific consultation, the science case was approved in October 2008 and the go-ahead given to continue the project to the design stage. In November the decision was taken that the facility will be based on cw superconducting technology in order to provide the best match to the scientific objectives. In this paper we present the source requirements, both for baseline operation and with possible upgrades, and the current status of the design of the accelerator driver and free-electron laser sources to meet those requirements.
FZK, Karlsruhe
Ruhr-Universität Bochum, Bochum
KIT, Karlsruhe
A linac based coherent radiation source in the THz to mid-IR range is proposed. The TBONE machine will deliver pulses of radiation as short as a few fs in the frequency range from 0.1 to 150 THz with up to MW peak power. This combination of parameters will open up unprecedented opportunities in THz and infrared applications, such as e.g. microscopy or spectroscopy. This paper presents the main parameters and design considerations. Special emphasis is put on the study of suitable bunch compression and beam transport schemes.
KEK, Ibaraki
Two synchrotron light sources of the Photon Factory storage ring (PF-ring) and the Photon Factory advanced ring (PF-AR) have been stably operated at KEK. PF-ring covers the photon-energy range from VUV to hard X-ray using a 2.5 GeV (sometimes 3.0 GeV) electron beam. PF-AR is mostly operated in a single-bunch mode of 6.5GeV to provide pulsed hard X-rays. Recently, the operation has progressed to realize a so-called top-up injection at PF-ring. In a single-bunch mode, the continuous injection to preserve a constant beam current of 51 mA has been carried out since February 2007. In addition, the injection with continuing the experiments has been successfully operated in a multi-bunch mode since October 2008. At PF-AR, sputter ion pumps have been extensively reinforced to prolong the beam lifetime and to reduce the frequency of sudden lifetime drops by substituting for distributed ion pumps, which are considered as one of the dust sources. In this conference, we present the recent progress of the operation at PF-ring and PF-AR including machine developments.
LBNL, Berkeley, California
SLAC, Menlo Park, California
Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contracts No. DE-AC02-05CH11231 (LBNL) and DE-AC02-76SF00515 (SLAC).
The future directions of x-ray science and the photon beam properties required to pursue them were recently evaluated by a joint LBNLSLAC study group*. As identified by this group, essential x-ray capabilities for light sources in the future (but not necessarily from any single source) include: 1) x-ray pulses with Fourier-transform-limit time structure from the picosecond to attosecond regime, synchronized with conventional lasers, and with control of longitudinal pulse shape, amplitude and phase; 2) full transverse coherence; 3) high average flux and brightness; 4) energy tunability in soft and hard x-ray regimes, and polarization control. Metrics characterizing source properties include not only average and peak spectral brightness but also the photons per pulse and repetition rate as a function of pulse length, and the proximity to transform-limited dimensions in six dimensional phase space. We compare the projected performance of various advanced x-ray source types, with respect to these metrics and discuss their advantages and disadvantages. We briefly discuss the technology challenges for future sources and the areas of R&D required to address them.
*R. Falcone, J. Stohr et al., “Scientific Needs for Future X-Ray Sources in the U.S. - A White Paper”, SLAC-R-910, LBNL-1090E, October 2008.
LLNL, Livermore, California
SLAC, Menlo Park, California
Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
We present a compact, X-band, high-brightness accelerator design suitable for driving a precision gamma-ray source. Future applications of gamma-rays generated by Compton-scattering of laser and relativistic electron beams place stringent demands on the brightness and stability of the incident electron beam. This design identifies the beam parameters required for gamma-ray production, including position, and pointing stability. The design uses an emittance compensated, 11.4 GHz photo-gun and linac to generate 400 pC, 1-2 mm-mrad electron bunches at up to 250 MeV and 120 Hz repetition rate. The effects of jitter in the photo-cathode laser and RF power system are analyzed as well as structure and optic misalignments and wakefields. Finally, strategies for the mitigation of on-axis bremsstrahlung noise are discussed.
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The X-ray Free Electron Laser Oscillator* (XFEL-O) is a concept for a high-brightness fourth-generation x-ray source with full spatial and temporal coherence. It is based on a CW electron source and superconducting linac. In order to reduce cost and increase versatility, a recirculating linac configuration is being entertained. In this paper, we present an optics design for the four-pass linac and the three recirculation systems. The design goals are preservation of the beam emittance and energy spread, as well as minimal cost and complexity. We also present the results of tracking studies that show the expected performance.
*K.J. Kim et al., Phys. Rev. Letters, to be published.
ASCo, Clayton, Victoria
Argonne National Laboratory, Office of Naval Research Project, Argonne
Monash University, Faculty of Science, Victoria
SLAC, Menlo Park, California
This paper describes the implementation of a neural network hybrid controller for energy stabilization at the Australian Synchrotron Linac. The structure of the controller consists of a neural network (NNET) feed forward control, augmented by a conventional Proportional-Integral (PI) feedback controller to ensure stability of the system. The system is provided with past states of the machine in order to predict its future state, and therefore apply appropriate feed forward control. The NNET is able to cancel multiple frequency jitter in real-time. When it is not performing optimally due to jitter changes, the system can successfully be augmented by the PI controller to attenuate the remaining perturbations.
DESY, Hamburg
WTM, Hamburg
This poster describes the organizational structures and processes which were established for coordinating civil construction at the European XFEL. Local managements supervise the different construction sites in cooperation with a central team which manages the overall effort and provides general services (e.g. coordination, communication, safety, legal). Communication processes, workflows for reviewing, approving and distributing construction drawings and formalized change management have been defined and established. Reporting, cost management and controlling procedures have been put in place, as well as procedures for maintaining good public relations. All the processes are documented in a project handbook, and they are supported and optimized by IT systems, in particular the DESY Engineering Data Management System, DESY EDMS.
DESY, Hamburg
In most sub-systems of the European XFEL, more than one institute participates in the design & development activities. This is the case for e.g. the cold linac, cryogenics, bunch compressors, undulators and photon beam systems. To ensure interface compatibility and make sure components fit into their complex environments, the collaborating institutes have to create high-level 3D models of their sub-systems. These 3D models are centrally integrated into a master model, which enables identification and elimination of collisions and non-conformities prior to manufacturing. A "collaborative design process", which supports efficient, interactive and inter-disciplinary cooperation of different institutes, has been successfully developed and established at the European XFEL. It consists of design guidelines and processes definitions for information & data exchange, reviews, approvals and change management. The process is supported by the DESY Engineering Data Management System, DESY EDMS, and allows the combination of 3D models from multiple 3D CAD systems. Following the good experience at the European XFEL, the same process is now established at the Global Design Effort for the ILC.
DESY, Hamburg
The European XFEL contains hundreds of sources of the coupled impedances. To have an overview of them an impedance budget database is developed. It contains wake functions of the point charge (Green functions) and allows to calculate the wake potentials for arbitrary bunch shapes.
Diamond, Oxfordshire
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
Several new light source projects aim at the production of X-ray photons with high repetition rate (1kHz or above). We present here the results of the start-to-end simulations of a 2.2 GeV superconducting LINAC based on L-band SC Tesla-type RF cavities and the corresponding optimisation of the FEL dynamics at 1 keV photon energy.
FEL/Duke University, Durham, North Carolina
BINP SB RAS, Novosibirsk
Funding: This work is supported by the US DoE grant #DE-FG02-01ER41175
A booster-injector synchrotron has been recently built and commissioned at Duke University to provide for the top-off injection into the storage ring in the energy range of 0.24 - 1.2 GeV. Booster injection kicker was designed with a pulse length of 18 out of 19 booster separatrixes, assuming a long train of electron bunches to be injected from the existing linac. Such scheme required a major linac upgrade from single bunch photo emission mode to a multibunch thermionic mode. A major disadvantage of the latter was much higher radiation levels in the facility. Since commissioning, the booster could only operate with one or two bunches limited by both long kicker pulse and single bunch injection from the linac. The consequent limitation of the injection rate restricted the capability of production of the Compton gamma rays in the loss mode, i.e. production of gammas with energy above 20-25 MeV, to about 5*108 photons per sec. Update of the linac for the repetition rate of up to 10 Hz, and modification of the injection kicker for 15 nS pulse length allowed us to developed an alternative multibunch injection scheme with a significant increase of the injection rate into storage ring.
INFN/LNF, Frascati (Roma)
The SPARX-FEL project aims at producing ultra high peak brightness electron beams in the 1.5 - 2.4 GeV range with the goal of generating FEL radiation in the 0.6-40 nm range. The construction is planned in two steps ,starting with a 1.5 GeV Linac. The project layout includes both RF-compression and magnetic chicane techniques, in order to provide the suitable electron beam to each one of three undulator systems which will generate VUV-EUV, Soft X-Rays and Hard X-rays radiation respectively This will be distributed in dedicated beamlines suitable for applications in basic science and technology: time resolved X-ray diffraction with pump and probe experiments, nanolithography processes, biological proteins, nano-particles and clusters, coherent diffraction and holographic X-ray techniques, nano-imaging. The project was funded by the Italian Department of Research, MIUR, and by the local regional government, Regione Lazio; The associated test-facility, SPARC, located at LNF, has been successfully commissioned: the SPARX-FEL project foresees the construction of a user facility inside the Tor Vergata campus by a collaboration among CNR, ENEA, INFN and the Università di Tor Vergata itself.
INFN/LNF, Frascati (Roma)
ENEA C.R. Frascati, Frascati (Roma)
ISM-CNR, Rome
The SPARX-FEL project consists in an X-ray-FEL facility which aim is the generation of electron beams characterized by ultra-high peak brightness at the energy of 1.5 and 2.4 GeV. This facility will be built in the Tor Vergata University area in Rome. The paper describe the engineering aspects of the mechanical design of the accelerator, photo-injector, LINACs, bunch compressors, beam distribution, undulators and experimental stations. Morover the integration of accelerator with the civil infrastractures is discussed.
ANL, Argonne
Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
ERL staging is a novel concept that provides a practical path to upgrading an existing synchrotron light source while minimizing disruption to the users and managing the technical risk. In the very first stage, the accelerator operating parameters are comparable to CEBAF without recirculation. Therefore, initially, energy recovery is not required and the injector is more modest. Consequently, the technical risk is significantly reduced relative to the full ERL. Using the APS as an example, the first stage is based on a full-energy, 7-GeV superconducting radiofrequency (srf) linac and an electron source that is almost off-the-shelf. The linac would initially deliver a low average current beam (<200 uA), but with a geometric emittance that is much smaller than the storage ring, the x-ray brightness can exceed the APS. Furthermore, the spatial coherence fraction would be about 100 times higher and the pulse length up to 100 times smaller than the APS. Valuable srf operating experience is attained at an early stage while allowing critical energy recovery issues to be studied. Energy recovery is commissioned in stage 2. The optics design and performance at each stage will be presented.
ANL, Argonne
Funding: This work was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The envisioned next-generation ERL-based x-ray light sources demand costly CW superconducting linacs and high-brightness high-current photoinjectors that are beyond the state of the art. To overcome the fiscal challenge of a multi-GeV CW superconducting ERL and the physical challenge of high-brightness high-current CW photoinjectors, we explore a new scheme using multi-beam injection into a quasi-CW ERL. Multi-beam injection lowers the burden on individual rf injectors at subharmonics of the linac frequency. Lower injector frequency allows higher bunch charge, which permits lower duty factor of the linac with significant reduction in construction and operation costs. Preliminary studies foresee many benefits and no obvious physical showstoppers, despite potential technical challenges. Here we provide a simulation study of a preliminary design.
KEK, Ibaraki
JAEA/ERL, Ibaraki
JASRI/SPring-8, Hyogo-ken
ISSP/SRL, Chiba
UVSOR, Okazaki
HU/AdSM, Higashi-Hiroshima
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
AIST, Tsukuba
Future synchrotron light source project using an energy recovery linac (ERL) is under proposal at the High Energy Accelerator Research Organization (KEK) in collaboration with several Japanese institutes such as the JAEA and the ISSP. We are on the way to develop such key technologies as the super-brilliant DC photo-injector and superconducting cavities that are suitable for both CW and high-current operations. We are also promoting the construction of the Compact ERL for demonstrating such key technologies. We report the latest status of our project, including update results from our photo-injector and from both superconducting cavities for the injector and the main linac, as well as the progress in the design and preparations for constructing the Compact ERL.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
STFC/DL, Daresbury, Warrington, Cheshire
UMAN, Manchester
FZD, Dresden
DESY, Hamburg
JLAB, Newport News, Virginia
KEK, Ibaraki
The University of Liverpool, Liverpool
STFC/DL/SRD, Daresbury, Warrington, Cheshire
STFC/RAL, Chilton, Didcot, Oxon
ACCEL, Bergisch Gladbach
ALICE (Accelerators and Lasers in Combined Experiments) is a 35 MeV energy recovery linac based light source. ALICE is being developed as an experimental test-bed for a broad suite of science and technology activities that make use of electron acceleration and ultra-short pulse laser techniques. This paper reports the progress made in accelerator commissioning and includes the results of measurement made on the commissioning beam. The steps taken to prepare the beam for short pulse operation as a driver for a Compton Back Scattered source and in preparation for the commissioning of the free electron laser are reported.
Plansee Metall GmbH, Reutte
W.C. Heraeus GmbH, Materials Technology Dept., Hanau
Sheet material made of high-purity Niobium (Nb-RRR) is the key component for future linear accelerators based on the superconducting radio-frequency technology. To be prepared for large production scale quantities, which are demanded for the upcoming projects like XFEL and ILC respectively, W.C. Heraeus (D) and Plansee SE (A) joined there competencies in the field of Nb-RRR. In 2007 the qualification procedure as material supplier for the XFEL project could be successfully finished and a complete product and technology package for products made of Nb-RRR was established. Based on the combination of the high expertise and long-term experience in electron beam melting of different Nb-RRR qualities; the knowledge and availability of various processing technologies for manufacturing of semi-finished and ready to assemble components; and the unique analytical capabilities for advanced quality control along the process chain customized product solutions can be realized for the accelerator industry. Beside a general overview about the production capabilities a strategy for installation of a Quality-Assurance-Management system for large production scale quantities are presented.
USTC/NSRL, Hefei, Anhui
In china, polymer radiation processing has become one of the most important processing industries. Electron beam accelerator or radioactive source is usually used as radiation processing source. For radiation crosslinking application, physical design, construction and testing of a electron beam facility is introduced because of it’s much higher dose rate and efficiency. Main part of this facility is a 10MeV traveling wave electron linac with constant impedance accelerating structure. It is the first electron beam facility designed for polymer radiation processing by National Synchrotron Radiation Laboratory (NSRL) in China. In the paper, a start to end simulation is finished to optimize electron beam dynamics in the linac. Measurement results of some subassemblies are presented. The linac construction has been finished just now. Testing experiments prove that the facility can work well for radiation crosslinking application.
UTNL, Ibaraki
The University of Tokyo, Nuclear Professional School, Ibaraki-ken
A, Kawasaki, Kanagawa
AET Japan, Inc., Kawasaki-City
We are developing X-ray nondestructive testing (NDT) system using with portable X-band linac. This system uses 9.4 GHz X-band linac and 250 kW magnetron. Our system energy is 950 keV for Japanese regulation. Therefore we can use it on-site using local radiation protection. We measured electron beam and X-ray. We have started X-ray imaging test. We will use this system for condition based maintenance of pump-impeller at nuclear plants. The linac based X-ray source can generate pulsed X-ray. Therefore we can get still images without stopping rotation when x-ray repetition rate synchronizes impeller's rotaion rate. We are successfull in proof of principle using a simple fan and a synchronized circuit. We prepare real-time imaging for conventional pump. In this paper, we will explain the detail of this system and expermental results.
AccSys, Pleasanton, California
AccSys has been built proton LINACs for medical applications such as Proton Beam Therapy (PBT), Positron Emission Tomography (PET) radioisotope production, and Boron Neutron Capture Therapy (BNCT). We will review the systems those have been shipped: For the PBT application, 6 systems have been shipped and under operation; for PET application, 5 systems have been shipped; for BNCT research application, one system has been shipped. We will also talk about high current proton linacs desired for BNCT and PET applications.
Siemens Med, Erlangen
Siemens DK, Jyllinge
Siemens has earned two contracts to deliver Particle Therapy* systems to be operated in Marburg and Kiel, both in Germany. The accelerator consists of an injector (7 MeV/u protons and light ions) and a compact synchrotron able to accelerate proton beams up to 250 MeV and carbon ions up to 430 MeV/u. These beams can be slowly extracted and delivered to a choice of fixed-angle horizontal, semi-vertical and vertical beam-ports. An overview of the design will be given. At the time of PAC09 installation of the first system will be nearing completion and commissioning will have started. Performance of some of the components and the status of the projects will be presented.
*Particle Therapy is a work in progress and requires country-specific regulatory approval prior to clinical use.
TRIUMF, Vancouver
The medical isotope Molybdenum-99 is presently used for 80-85% of all nuclear medicine procedures and is produced by irradiating highly enriched uranium U-235 targets in nuclear reactors. It has been proposed* that an electron linac be used for the production of 99Mo via photo-fission of a natural uranium target. The nominal linac parameters are 50 MeV electron energy, 100 mA beam current and 100% duty factor. This paper describes two possible superconducting RF accelerator design concepts based on the frequencies of 704 MHz and 1.3 GHz. We present design parameters, efficiency and reliability estimates, and comparisons between the two options. Finally, we describe how the proposed e-linac project at TRIUMF can be used for proof-of-principle demonstration and critical validation tests of the accelerator-based production of 99Mo.
*Making Medical Isotopes: Report of the Task Force on Alternatives for
Medical-Isotope Production (2008)
TRIUMF, Vancouver
JLAB, Newport News, Virginia
The medical isotope Molybdenum-99 is presently used for 80-85% of all nuclear medicine procedures and is produced by irradiating highly enriched uranium U-235 targets in NRU reactors. It was recently proposed that an electron linac be used for the production of 99Mo via photo-fission of a natural uranium target coming from the excitation of the giant dipole resonance around 15 MeV. The photons can be produced using the braking radiation (“bremsstrahlung”) spectrum of an electron beam impinged on a high Z material. In this paper we present an alternate concept for the production of 99Mo which is also based on photo-fission of U-238, but where the ~15 MeV gamma-rays are produced by Compton backscattering of laser photons from relativistic electrons. We assume a laser wavelength of 330 nm, resulting in 485 MeV electron beam energy, and 10 mA of average current. Because the induced energy spread on the electron beam is a few percent, one may recover most of the electron beam energy, which substantially increases the efficiency of the system. The accelerator concept, based on a three-pass recirculation system with energy recovery, is described and efficiency estimates are presented.
TUB, Beijing
IHEP Beijing, Beijing
CIAE, Beijing
ANL, Argonne
KEK, Tsukuba
Funding: Supported by the “985 Project” of the Minister of Education of China, CAS Bairen Init. (KJCX2-YW-N22), CAS Overseas Outstanding Youth Program, and the National Natural Science Foundation (10628510).
During the past decades, large-scale national neutron sources are developed in Asia, Europe, and USA. Complementing such efforts, compact hadron beam complexes and neutron sources intended for universities and industrial institutes are proposed and established. Responding to the demands in China for multidisciplinary researches and applications using pulsed neutrons and protons, hadron therapy and radiography, and accelerator-driven sub-critical reactor systems (ADS) for nuclear waste transmutation, we here propose a compact yet expandable accelerator complex based on a proton source, a 3 MeV RFQ linac, and a 22 MeV DTL linac. A Be target with solid methane and room-temperature water moderators serve 6 neutron stations for imaging/radiography, irradiation, SANS, engineering powder diffraction, instrumentation, and therapy. The proton platform serves multiple stations for bio-applications, fuel cell and nano-applications, and space irradiation and detection. A rapid cycling synchrotron subsequently accelerates the beam to up to 300 MeV for proton therapy and radiography. Following the DTL linac with a superconducting RF linac and a sub-critical reactor offers an ADS test facility.
INFN - Gruppo Messina, S. Agata, Messina
Università di Messina, Messina
INFN-Cagliari, Monserrato (Cagliari)
INFN-Ferrara, Ferrara
At the Dipartimento di Fisica, Università di Messina, an X-ray source based on a 5 MeV electron linac has been designed. By means of the MCNP-4C2 code, several simulations have been performed to evaluate if the source can be used as a NDT device for material recognition purposes. In particular, being able to vary the electron beam energy for producing bremsstrahlung beams with different absorption, X-ray transmission through several materials and for different X-ray beams energy has been studied. First results have shown the capability of the system to distinguish dissimilar materials by properly choosing the X-ray beam end-point energy and processing the obtained transmission values. Since the uncertainties level in the material identification could be improved differentiating the response of the imaging system, a theoretical study has been performed to evaluate how X-ray beams obtained with different end-point energies, and eventually transmitted by properly chosen filters, are absorbed by different scintillators. The obtained results will be presented and discussed in order to give indications on the real chance to use the designed device for material recognition purposes.
IBS, Atlanta, Georgia
MEPhI, Moscow
In today’s turbulent and unsecure world, an X-ray radiographic image and a dual-energy Z-detection mapping of a container contents are needed to provide a reasonable level of port and border security. An interlaced dual-energy electron-beam linac has been developed for the use in cargo inspection systems to meet this growing need. Electron energy of the linac is software controllable from 3 to 15 MeV. Nominal operating energy levels of 4 and 9 MeV were chosen. The 9 MeV beam energy operating point is used for generating the X-ray radiographic image while 4 and 9 MeV beams are used for Z-detection mapping. The S-band linac has been calculated, designed, built and tested. Frequency repetition rate of alternating 4 and 9 MeV beams is 240 Hz. Pulse length is 10 μs. The beam energy in each beam pulse is over 10 J.
RadiaBeam, Marina del Rey
UCLA, Los Angeles, California
The fixed-field alternating-gradient (FFAG) betatron has emerged as a viable alternative to RF linacs as a source of high-energy radiation for industrial and security applications. RadiaBeam Technologies is currently developing an FFAG betatron with a novel induction core made with modern low-loss magnetic materials. The principle challenge in the project has been the design of the magnets. In this paper, we present the current status of the project, including results of the magnet design and testing.
CERN, Geneva
TU Vienna, Wien
Minimization of direct space charge tune shift at injection into the PS2 is important for the reduction of beam losses. A determining parameter for the tune shift is the bunching factor, defined as mean current over peak current for one RF period. Various longitudinal painting schemes for PS2 injection, all based on synchrotron motion, have been studied with respect to the resulting bunching factors. In particular, schemes using the SPL high-frequency chopper and different energy-spreads and offsets of the incoming beam as well as SPL beam energy modulations on have been simulated with the ESME code.
Fermilab, Batavia
Funding: Work supported by the Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359 with the U.S. Dept. of Energy.
Project-X is a leading candidate of the next major accelerator construction project at Fermilab. The mission need of Project-X is to establish an intensity frontier for particle physics research, or more precisely, to build a multi-MW proton source for neutrino and other particle studies. Coupled with an upgraded Main Injector (MI) and Recycler, an 8 GeV superconducting RF (SRF) H linac meets this need. However, a more cost effective approach would be a hybrid design, namely, a combination of a 2 GeV SRF linac and an 8 GeV rapid cycling synchrotron (RCS) in lieu of an 8 GeV SRF linac. This alternative design also meets the mission need but at a lower cost since a synchrotron is cheaper than a SRF linac. It retains the ability to use a 2 GeV SRF linac for ILC technology development. It reuses the existing Debuncher enclosure and Booster RF. The transport line of 2 GeV H particles is shorter than the present 8 GeV design. The requirement of a cryogenic beam screen can be eliminated. The efficiency of stripping foil is higher and injection loss (kJ) will be lower.
*W. Chou, “A Simple Transition-Free Lattice of an 8 GeV Proton Synchrotron,” this conference.
Fermilab, Batavia
Injection painting enables the mitigation of space charge and stability issues, and may be indispensable for the Project-X at Fermilab, delivering high-intensity proton beams to HEP experiments. Numerical simulations of multi-turn phase space painting have been performed for the FNAL Recycler Ring, including a self-consistent space charge model, lattice nonlinearities, H- stripping, particle loss and foil heating. Different painting waveforms were studied to build a uniform (KV-like distribution) and other phase space distributions.
KAERI, Daejon
BNL, Upton, Long Island, New York
Funding: This work is supported by Ministry of Education, Science and Technology of the Korean government.
The proton engineering frontier project (PEFP) is designing the rapid cycling synchrotron (RCS) whose main purpose is the spallation neutron source. The PEFP 100-MeV linac will be the injector to the RCS. The output energy and beam power are 1 GeV and 60 kW at the initial stage. We studied the H- charge exchange injection with transverse and momentum painting schemes. In order to enhance the machine versatility, we studied the slow extraction options for the nuclear physics and medical research in addition to the single turn extraction for the spallation neutron source. This paper summarizes the present status of the physics design of the RCS.
KEK, Ibaraki
JAEA/LINAC, Ibaraki-ken
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
The output energy of J-PARC linac is planned to be upgraded from 190 MeV to 400 MeV by adding an ACS (Annular Coupled Structure linac) section. The ACS is a variety of coupled-cavity structure linac newly devised for former JHP (Japan Hadron Project), and its original beam dynamics design for J-PARC was presented in LINAC02 [M. Ikegami et. al., in Procs. of LINAC02, p. 629]. Extensive R&D studies have been conducted since then to establish the feasibility of ACS, where four ACS modules have been fabricated and successfully high-power tested. In parallel, the beam dynamics design of the ACS has been further optimized to reflect the experience obtained in the R&D studies and reduce the cost for mass production. In this paper, the revised beam dynamics design of the J-PARC ACS is presented with some simulation results with a particle simulation code.
NSCL, East Lansing, Michigan
An 8 GeV proton linac is being considered for the Fermilab accelerator complex. A design calls for five superconducting cavity types: three types of half-wave and two types of multi-cell elliptical structures. The elliptical cavity types have a frequency of 1.3 GHz with a beta = 0.81 and a beta = 1 and provide acceleration from 420 MeV to 8 GeV. An alternative concept would be to use an additional 1.3 GHz elliptical cavity type starting at 150 MeV. The alternative design may reduce project cost and risk. It would increase the technology overlap between Project X and the International Linear Collider. Preliminary simulations show the alternative linac layout has adequate longitudinal acceptance. This paper will discuss the beam dynamics studies for the alternative linac layout in comparison with the baseline layout.
ORNL, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
The Spallation Neutron Source (SNS) is a second generation pulsed-neutron source and designed to provide a 1-GeV, 1.44-MW proton beam to a mercury target for neutron production. Since the initial commissioning of accelerator complex in 2006, the SNS has begun neutron production operation and beam power ramp-up has been in progress toward the design goal. Since the design beam power is almost an order of magnitude higher compared to existing neutron facilities, all subsystems of the SNS were designed and developed for substantial improvements compared to existing accelerators and some subsystems are first of a kind. Many performance and reliability aspects were unknown and unpredictable, for which it takes time to understand the systems as a whole and/or needs additional performance improvements. A power ramp-up plan has been revised based on the operation experiences and understandings of limits and limiting conditions through extensive studies with an emphasis on machine availability. In this paper the operational experiences of SNS Superconducting Linac (SCL), the power ramp-up status and plans will be presented including related subsystem issues.
Fermilab, Batavia
A new experimental area, the Muon Test Area, has been constructed to develop, test, and verify muon ionization apparatus using the 400-MeV proton beam from the Fermilab Linac. Since muon-cooling apparatus is being developed for facilities that involve the capture, collection and cooling of ~1013 muons at a repetition rate of 15 Hz, conclusive tests require full Linac beam, or ~1013 protons/pulse at 15 Hz. A beamline has been designed which includes specialized insertions for linac beam diagnostics and beam measurements, greatly enhancing the functionality of the line in addition to providing beam for MTA experiments. Installation of the beamline is complete and first beam was achieved in November, 2008. The design, operational flexibility, and characteristics of the MTA beamline will be presented.
Bilbao, Faculty of Science and Technology, Bilbao
ESS Bilbao, Bilbao
Elytt Energy, Madrid
Funding: ESS-Bilbao Consortium
A baseline design for the proton linear accelerator as proposed by the European Spallation Source-Bilbao bid to host the installation (ESS-B) is here described. The new machine concept incorporates advances which have been registered within high power accelerators during the last decade. The design of such a new accelerator layout heavily relies upon low-beta superconducting spoke resonators which are already under development.
BNL, Upton, Long Island, New York
CEA, Gif-sur-Yvette
ESS-S, Lund
Fermilab, Batavia
CERN, Geneva
Funding: ESS-S Scandinavia Consortium
The conceptual design of the European Spallation Source-Scandinavia (ESS-S) is presented. The accelerator system baseline draws heavily on state-of-the-art mature technologies that are being employed in the CERN Linac4 and SPL projects, although advances with spoke resonator and sputtered superconducting cavities are also being evaluated for reliable performance. Irradiation damage due to proton beam losses is a key issue for linac and target components. Their optimized design is performed from an engineering perspective, using the last updated versions of mechanical design codes which were already qualified for irradiated components. Finally, future upgrades of power and intensity of the proton linac are considered, including the design optimization of the Target Station (proton/neutron convertor), with the possibility of increasing the average pulsed power deposition up to 7.5 MW. All possible upgrades will be taken into account for the final design review, in the frame of the costs and constraints given with the site decision.
CERN, Geneva
The CERN Proton Synchrotron Booster (PSB) has been running for more than 30 years. Originally designed to accelerate particles from 50 to 800 MeV, later upgraded to an energy of 1 GeV and finally 1.4 GeV, it is steadily being pushed to its operational limits. One challenge is the permanent demand for intensity increase, in particular for CNGS and ISOLDE, but also in view of LINAC4. As it is an accelerator working with very high space charge during the low energy part of its cycle, its operational conditions have to be precisely tuned. Amongst other things resonances must be avoided, stop band crossings optimized and the machine impedance minimized. Recently, an operational intensity record was achieved with >4.25·1013 protons accelerated. An orbit correction campaign performed during the 2007/2008 shutdown was a major contributing factor to achieving this intensity. As the PSB presently has very few orbit correctors available, the orbit correction has to be achieved by displacing and/or tilting some of the defocusing quadrupoles common to all 4 PSB rings. The contributing factors used to optimize performance will be reviewed.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
LASTI, Hyogo
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
KEK, Ibaraki
J-PARC, KEK & JAEA, Ibaraki-ken
The beam commissioning of the J-PARC 3-GeV RCS started in October 2007. The initial machine parameter tuning and underlying beam studies were completed in February 2008 through various beam dynamics measurements, such as optical functions, turn-by-turn beam positions, and transverse and logitudinal beam profiles. Now the RCS is in transition from the first commissioning phase to the next challenging stage and our efforts hereafter will be focused on higher beam power operations. In this paper, we describe experimental results obtained in the high intensity demonstrations in October 2008, together with the corresponding simulation results.
IHEP Beijing, Beijing
The 1.6GeV proton synchrotron proposed in the CSNS Project is a 25Hz rapid-cycling synchrotron (RCS) with 80MeV Linac. Beam power is aimed to 100kW at 1.6GeV. In this paper the designs of the prototype of DTL-Q power supply and the prototype of the resonant network with one mesh exciting in series will be introduced.
SLAC, Menlo Park, California
Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515
This paper will report on the test results of a prototype 1320 watt power module for a high availability power supply. The module will allow parallel operation for N+1 redundancy with hot swap capability. The two quadrant output of each module allows pairs of modules to provide a 4 quadrant (bipolar) operation. Each module employs a novel 4 FET buck regulator arranged in a bridge configuration. Each side of the bridge alternately conducts through a small saturable ferrite that limits the reverse current in the FET body diode during turn off. This allows hard switching of the FETs with low switching losses. The module is designed with over-rated components to provide high reliability and better then 97% efficiency at full load. The modules use a Microchip DSP for control, monitoring, and fault detection. The switching FETS are driven by PWM modules in the DSP at 60 Khz. A Dual CAN bus interface provides for low cost redundant control paths. The DSP will also provide current sharing between modules, synchronized switching, and soft start up for hot swapping. The input and output of each module have low resistance FETs to allow hot swapping and isolation of faulted units.
CERN, Geneva
For the LINAC4 project the PS Booster (PSB) injection system will be upgraded. The 160 MeV H- beam will be distributed to the 4 superimposed PSB synchrotron rings and horizontally injected by means of an H- charge-exchange system. Operational considerations for the injection system are presented, including expected beam losses from field stripping of H- and excited H0 and foil scattering, possible injection failure cases and expected stripping foil lifetimes. Loading assumptions for the internal beam dumps are discussed together with estimates of doses on various components.
INFN/LASA, Segrate (MI)
Istituto Nazionale di Fisica Nucleare, Milano
INFN-Roma II, Roma
INFN/LNF, Frascati (Roma)
High vacuum has always been mandatory in particle accelerator. This is true especially for circular machine, where the beam make thousands or millions turns, and beam lifetime is heavily affected by the residual gas scattering. In dimensioning the interaction chamber for a plasma accelerator experiment, because of gas needed and the diagnostics and control devices foreseen, the problem of the effect of the residual gas on the beam arose. Simulation of the beam interaction with the residual gas in the chamber has been performed with FLUKA code. The effects of different vacuum levels on the electron beam is reported and consequences on the beam quality in linacs is discussed.
JLAB, Newport News, Virginia
ODU, Norfolk, Virginia
Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The CEBAF accelerator at Jefferson Lab has had, since first demonstration in 1996, the ability to deliver a 5-pass electron beam to experimental halls (A, B, and C) simultaneously. This capability was provided by a set of three, room temperature 499 MHz rf separators in the 5th pass beamline. The separator was two-rod, TEM mode type resonator, which has a high shunt impedance. The maximum rf power to deflect the 6 GeV beams was about 3.4kW. The 12 GeV baseline design does not preserve the capability of separating the 5th pass, 11 GeV beam for the 3 existing halls. Several options for restoring this capability, including extension of the present room temperature system or a new superconducting design in combination with magnetic systems, are under investigation and are presented.
NSCL, East Lansing, Michigan
Funding: Michigan State University
The National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) is implementing a system called the ReA3 to reaccelerate rare isotope beams from projectile fragmentation to energies of about 3 MeV/u. The 80.5 MHz triple-harmonic buncher before the ReA3 Radio Frequency Quadrupole (RFQ) linac has recently been implemented and measurements made. Tests using beams from the Electron Cyclotron Resonance (ECR) ion source test stand are being performed. The beam properties after the buncher are fully characterized using various diagnostic tools (e.g. fast Faraday cup, energy analyzer, emittance scanner). As a result, the tuning procedures for the buncher operations are developed. We will present the detailed results of the beam based buncher studies and compare them with simulations.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
Funding: Supported by STFC/RAL/ASTeC and by EC Research Infrastructure Activity (FP6) "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395).
A description is given of the development of a slow-wave chopper structure for the 3.0 MeV, 60 mA, H‾ MEBT on the RAL Front-End Test Stand (FETS). Two candidate structures, the so called RAL ‘Helical’ and ‘Planar’ designs have been previously identified, and are being developed to the prototype stage. Three test assemblies have been designed by modelling their high frequency electromagnetic properties in the time domain, using a commercial 3D code, and their subsequent manufacture, using standard NC machining practice, has helped to validate the selection of machine-able ceramics and copper alloys. In addition, an electro-polishing technique has been developed that enables the ‘fine tuning’ of strip-line characteristic impedance, and edge radius. Measurements of the transmission line properties of the ‘Helical’ and ‘Planar’ test assemblies are presented.
IHEP Beijing, Beijing
China Spallation Neutron Source is a high intensity beam facility planed to build in future in China. It is composed of Linac, RCS and target station. Two sets of pulsed painting bump magnets, 4 magnets in each set , will be used in CSNS RCS to create a dynamic orbit bump for injection process. The design of these 8 bump magnets has been completed. One prototype bump magnet has been assembled and tested. In this paper, the magnetic field analysis, the eddy current and thermal consideration in the end plates of the prototype bump magnet are presented, and issues of the magnet development, construction and test are discussed.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
The main circuit of the switching power supplies for the injection bump system is composed of multiple-connection of the IGBT assemblies. The element of the IGBT assembly, which is the power supply of the shift bump-magnets, is a type of 3300V-1200A and 6 kHz in elementary frequency. The power supply has the output performance of 20 kA / 6.6 kV. The synthetic frequency of the multiple-connection assemblies is over 48 kHz and the tracking error less than 1 % is proved. The beam commissioning test of long-term operation for about three-week was performed. The deviation of the exciting current from the programmed current pattern has been confirmed less than 1%. The peculiar characteristic of the pulse power supply has been obtained by the analysis on the frequency response of the exciting current and the magnetic field. In the FFT analytical result of the magnetic field, the peaks of 48 kHz and its higher harmonics that are related to the switching frequency was observed. The ground loop current and the voltage were also measured.
SLAC, Menlo Park, California
Funding: Work supported by the Department of Energy under contract No. DE-AC02-76SF00515.
The design and installation of the Linac Coherent Light Source* at SLAC National Accelerator Laboratory has included the development of a kicker system for selective beam bunch dumping. The kicker is based on an LC resonant topology formed by the 50 uF energy storage capacitor and the 64 uH air core magnet load and has a sinusoidal pulse period of 400us. The maximum magnet current is 500 A. The circuit is weakly damped, allowing most of the magnet energy to be recovered in the energy storage capacitor. The kicker runs at a repetition rate of 120Hz. A PLC-based control system provides remote control and monitoring of the kicker via EPICS protocol. Fast timing and interlock signals are converted by discrete peak-detect and sample-hold circuits into DC signals that can be processed by the PLC. The design and experimental characterization of the systems is presented.
*http://ssrl.slac.stanford.edu/lcls/
SLAC, Menlo Park, California
ORNL, Oak Ridge, Tennessee
Funding: Work supported by the Department of Energy under contract No. DE-AC02-76SF00515.
The 1-MW High Voltage Converter Modulators* have operated in excess of 250,000 hours at the Spallation Neutron Source. Increased demands on the accelerator performance require increased modulator reliability. An effort is underway at SLAC National Accelerator Laboratory to redesign the modulator H-bridge switch plate with the goals of increasing reliability and performance**. The major difference between the SLAC design and the existing design is the use of press-pack IGBTs. Compared to other packaging options, these IGBTs have been shown to have increased performance in pulsed-power applications, have increased cooling capability, and do not fragment and disassemble during a fault event. An overview of the SLAC switch plate redesign is presented. Design steps including electrical modeling of the modulator and H-bridge, development of an integrated IGBT clamping mechanism, and heat sink performance validation are discussed. Experimental results will be presented comparing electrical performance of the SLAC switch plate to the existing switchplate under normal and fault conditions.
*W. A. Reass, et al., “Design, Status, and First Operations of the Spallation Neutron Source Polyphase
”, PAC, 2003
**M.A. Kemp, et al., “Next Generation IGBT Switch Plate
,” LINAC, 2008.
ORNL, Oak Ridge, Tennessee
Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
The Spallation Neutron Source (SNS) has operated at beam powers over 650 kW, and is expecting to approach 1 MW operation by the summer of 2009. Challenges in operating a proton accelerator at these power levels is reducing the uncontrolled beam loss to levels approaching 10-6/meter, and ensuring machine protection. Experience with beam tuning and safely handling the high power will be presented. Also the progress in beam loss reduction over the course of the power ramp-up will be reviewed.
On behalf of the SNS Team
Fermilab, Batavia
Funding: FRA
Fermilab’s High Intensity Neutrino Source (HINS), the 325 MHz low energy section of Project X consists of an RFQ, 18 copper cavities and a section of superconducting spoke resonator cavities, all driven by a single 2.5 MW klystron. Each cavity has a high power ferrite vector modulator which provides individual RF power control. This paper proposes a scheme that optimizes RF drive and vector modulator control. The different gradients, acceleration phase angles, unloaded Q’s and beam loading are taken into account to optimize the cavities detuning angles, forward power, and loaded Q’s. This scheme makes an efficient use of the klystron’s high bandwidth ability to modulate the forward power, hence minimizing the burden on the high power vector modulator during the RF pulse. The proposed method is explained in details, a parameter sensitivity analysis is performed and the impact on the total power consumption for the RF station is calculated.
BARC, Trombay, Mumbai
Indian Institute of Technology Bombay, Mumbai
TIFR, Mumbai
As a first step towards development in digital domain, a computer model of a self excited loop (SEL) has been created using MATLAB/SIMULINK. The behaviour of a resonator and a power amplifier combination has been approximated using two first-order differential equations. The square of the amplitude of the RF field in the resonator acts as a driving force for the motion of mechanical modes of the resonator, which are individually represented as second order systems. A key element is the limiter, which has been modelled as a feedback loop, to achieve constant output amplitude. The model has been created in the I-Q domain for computational efficiency and close correspondence with actual implementation. To study the field stabilisation, proportional amplitude and phase feedback loops have been appended to the model of the SEL. In this paper we discuss the details of the model and results from simulation. Initial experimental results are also presented.
RISE, Tokyo
KEK, Ibaraki
Kyoto University, Kyoto
Funding: Work supported by a Grant-In-Aid for Creative Scientific Research of JSPS (KAKENHI 17GS0210) and a Grant-In-Aid for JSPS Fellows (19-5789)
We have been developing a pulsed-laser storage technique in a super-cavity for compact X-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, using 357 MHz mode-locked Nd:VAN laser pulses which stacked in a super-cavity scattered off a multi-bunch electron beam, we obtained multi-pulse X-rays through laser-Compton scattering. Detecting an X-ray pulse-by-pulse using a high-speed detector makes it possible to measure the 3-dimensional beam size with bunch-by-bunch scanning the laserwire target position and pulse timing. This technique provides not only the non-destructive beam profile monitoring but also the measuring of bunch length and/or bunch spacing shifting. In our multi-bunch electron linac, the bunch spacing narrowing due to the electron velocity difference in the train at the output of rf-gun cavity was observed. The principle of the 3-dimensional laserwire monitor and the experimental results of multi-bunch electron beam measurements will be presented at the conference.
TRIUMF, Vancouver
DAE/VECC, Calcutta
A 0.5 megawatt electron linear accelerator is being designed at TRIUMF in support of its expanding rare isotope program, which targets nuclear structure and astrophysics studies as well as material science. The first stage of the project, a 25 MeV, 5 mA, cw linac matching the isotope production target power-handling capability in the next five-year plan, is planned to be completed in 2013. The injector cryomodule development, which is being fast tracked, is the subject of a scientific collaboration between TRIUMF and the VECC laboratory in Kolkata, India. The paper gives an overview of the accelerator design progress.
JAEA/J-PARC, Tokai-mura
KEK, Ibaraki
KEK/JAEA, Ibaraki-Ken
J-PARC consists of a 181 MeV linac, a 3GeV Rapid Cycling Synchrotron (RCS) and a 50 GeV Synchrotron (MR). The RCS is designed to accelerate a high intensity proton beam. One of the key issues of the RCS RF system is how to achieve the very high accelerating field gradient of more than 20kV/m. This is impossible with conventional ferrite-loaded cavities. We reach this goal by the development of Magnetic Alloy (MA) core loaded RF cavities. We installed 10 RF cavities in the RCS tunnel on May 2007. The RCS beam commissioning was started on September 2007 and we successfully accelerated a proton beam up to 3GeV on October 2007. We also employed MA cores for MR RF cavities and use a cut core configuration to adjust the Q-value. The MR beam commissioning was started on May 2008. We didn't have any trouble caused by the MA cores during operation. We measured the impedance of the RF cavities several times at the shutdown periods. We show the results of impedance measurements. From these results, we can make an assumption about the core condition.
RadiaBeam, Marina del Rey
UCLA, Los Angeles, California
NCSU, Raleigh, North Carolina
INFN/LNF, Frascati (Roma)
Electron beam based additive fabrication techniques have been successfully applied to produce a variety of complex, fully dense, metal structures. These methods, collectively known as Solid Freeform Fabrication (SFF) are now being explored for use in radio frequency (RF) structures. SFF technology may make it possible to design and produce near-netshape copper structures for the next generation of very high duty factor, high gradient RF photoinjectors. The SFF process discussed here, Arcam Electron Beam Melting (EBM), utilizes an electron beam to melt metal powder in a layer-by-layer fashion. The additive nature of the SFF process and its ability to produce fully dense parts are explored for the fabrication of internal cooling passages in RF photoinjectors. Following an initial feasibility study of the SFF process, we have fabricated a copper photocathode, suitable as a drop-in replacement for the UCLA 1.6 cell photoinjector, with internal cooling channels using SFF. Material analysis of the prototype cathode and new designs for a high duty factor photoinjector utilizing SFF technology will be presented.
SAMEER, Mumbai
Shunt impedance of an accelerating structure is an important parameter. It gives an idea of the power coupled to the beam. A 6 MeV to 15 MeV ‘S’ band standing wave side coupled linac structure is developed in SAMEER*. The measurement of the shunt impedance of the cavity is done using bead pull method. The shunt impedance is calculated after plotting the electric field profile. The calculation is done using a C code which first calculates the area of the plot and then uses appropriate variables to give the final value of the shunt impedance. The automation of the bead pull setup is planned and then the integration of calculation and automated setup. This paper describes the method used in the code and outlines the results of the measurement.
*R.Krishnan et.al. submitted in this conference.
SLAC, Menlo Park, California
CERN, Geneva
KEK, Ibaraki
Funding: Work supported by the DOE under contract DE-AC02-76SF00515
As part of a SLAC-CERN-KEK collaboration on high gradient X-band structure research, several prototype structures for the CLIC linear collider study have been tested using two of the high power (300 MW) X-band rf stations in the NLCTA facility at SLAC. These structures differ in terms of their manufacturing (brazed disks and clamped quadrants), gradient profile (amount by which the gradient increases along the structure which optimizes efficiency and maximizes sustainable gradient) and HOM damping (use of slots or waveguides to rapidly dissipate dipole mode energy). The CLIC goal in the next few years is to demonstrate the feasibility of a CLIC-ready baseline design and to investigate alternatives which could bring even higher efficiency. This paper summarizes the high gradient test results from the NLCTA in support of this effort.
SLAC, Menlo Park, California
Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
We present a concept for powering the main linacs of the International Linear Collider (ILC) by delivering high power RF from the surface via overmoded, low-loss waveguides at widely spaced intervals. The baseline design employs a two-tunnel layout, with klystrons and modulators evenly distributed along a service tunnel running parallel to the accelerator tunnel. This new idea eliminates the need for the service tunnel. It also brings most of the warm heat load to the surface, dramatically reducing the tunnel water cooling and HVAC requirements. In the envisioned configuration, groups of 70 klystrons and modulators are clustered in surface buildings every 2.4 km. Their outputs are combined into two half-meter diameter circular TE01 mode evacuated waveguides. These are directed via special bends through a deep shaft and along the tunnel, one upstream and one downstream. Each feeds approximately 1.2 km of linac with power tapped off in 10 MW portions at 38 m intervals. The power is extracted through a novel coaxial tapoff (CATO), after which the local distribution is as it would be from a klystron. This tapoff design is also employed in reverse for the initial combining.
ELETTRA, Basovizza
Funding: The work was supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3
FERMI@Elettra is a seeded FEL user facility under construction at Sincrotrone Trieste, Italy. The linac is based on S-band normal conducting technology. It will use the accelerating sections of the original Elettra linac injector, seven sections received from CERN after LIL decommissioning and two additional sections to be constructed for a total number of 18 S-band accelerating structures. Installation of the machine is presently being carried on. This paper will provide a summary of the requirements of the different parts of the S-band RF system and of the options for a possible upgrade path both in energy and reliability. The ongoing activities on the main subassemblies, in particular regarding the tests and the installation work, are also presented.
ELETTRA, Basovizza
Funding: The work was supported in part by the Italian Ministry of University and Research under grant FIRB-RBAP045JF2 or grant FIRB-RBAP06AWK3 or grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3
The FERMI@ELETTRA project will use the existing ELETTRA linac. The linac includes seven accelerating sections, each section is a backward traveling (BTW) structure comprised of 162 nose re-entrant cavities coupled magnetically. Furthermore, there are specialized input and output cavities specifically designed to match the structure to the RF source and load. These BTW accelerating structures work on the 3pi/4 mode which was chosen to optimize the structure efficiency and to achieve a simple RF tuning setup. These accelerating sections are powered by a TH2132A 45 MW klystron providing a 4.5 microsecond rf pulse and are coupled to a Thomson CIDR. In this paper the 3pi/4 backward BTW structures are investigated and the results of the electromagnetic simulations are presented.
USTC/PMPI, Hefei, Anhui
USTC/NSRL, Hefei, Anhui
Funding: "Collinear Load for Accelerators and R&D on High Power Microwave Absorbed Material" No.10775128 From National Natural Science Foundation of China
Thermal deformation caused by Non-uniform temperature distribution in disk-loaded waveguide will affect the resonant frequency of LINAC deeply. Formerly, researchers evaluated it by experiments or experience and gave their conclusion roughly and linearly. A new approach of integration of multi-disciplinary is adopted to study the relationship more accurately. After loading the loss RF power on the accelerator tube wall, the thermal deformation is calculated in software I-DEAS, and a deformed finite element model is obtained. Then nodes on inner surfaces of the cavities were extracted and sort by a customized program. According to these nodes, a new solid model is reconstructed with a self developed 3D reconstruction technology in ANSYS. B-Spline interpolation technique is used to fit a group of curves first, and then to reconstruct NURBS surfaces. The final reconstructed deformed solid model, obtained by closing the surfaces, can be exported in IGES format which is used to recalculate the resonant frequency in Microwave Studio again. The error of the reconstruction can be controlled within 3 micrometers. The resonant frequency change of every cavity can be accurately calculated.
Parietti L, etc., Thermal structural analysis and frequency shift **
Zhou, Zu-Sheng,etc. Thermal structural analysis and test **
INFN/LASA, Segrate (MI)
DESY, Hamburg
Cavity tuners are needed to precisely tune the resonant frequency of TESLA SC cavities for European XFEL linac. Although several units of the currently used device, originally designed at Saclay for TTF and then developed at DESY, have been manufactured and tested so far, a permanent installation like the XFEL poses higher requirements in terms of reliability and reproducibility. XFEL indeed requires about {10}00 tuners to be produced in a relatively short time and then to simultaneously work in cryogenic environment, each of them being equipped with a stepper motor driving unit and two piezoelectric actuators. In this frame, an acceptance test procedure, here presented, has been studied, its main goal being the cross-check of issues affecting reliability: installation, mechanical coupling of active elements to cavity, motor and fast actuators functionality. An electronic equipment has been developed for driving signals, sensors and data management, specifically aiming toward an automatic and user-friendly routine in view of a large scale application. The procedure has been then applied for calibration purposes of a sample cavity assembly, the experimental results are also presented.
INFN/LASA, Segrate (MI)
BESSY GmbH, Berlin
An extensive validation activity has been conducted since year 2007 for the coaxial Blade Tuner for TESLA SC cavities. During this activity, performances and limits of prototype models have been deeply investigated through detailed test sessions inside CHECHIA (DESY) and HoBiCaT (BESSY) horizontal cryostats as well as F.E. modeling and analyses. The result is an improved design for the Blade Tuner, specifically meant to satisfy the incoming ILC-level performance requirements, fulfill pressure vessels regulations and keep Ti / S.S. material compatibility. Recent Blade Tuner activities and results will be presented in this paper in view of the installation of 8 units in the second cryomodule of ILCTA facility at Fermilab, and also of our contribution to both incoming S1-Global (KEK) and ILC-HiGrade projects. The manufacturing process of the first set of 8 tuners, from production to room temperature validation for the whole series, will be also reviewed. Then results will be shown from the cold tests recently performed, where special effort has been made in evaluating the accuracy and repeatability of fast and slow tuning action at few Hz range.
INFN/LASA, Segrate (MI)
DESY, Hamburg
Three superconducting 3.9 GHz cavity prototypes have been fabricated for the XFEL linac injector, with minor modifications to the rf structures built by FNAL for the FLASH linac. This paper describes the production and preparation experience, the initial measurements, the plans for the XFEL series production and the cryogenic test infrastructure under preparation at INFN Milano.
NSCL, East Lansing, Michigan
A medium-velocity half wave resonator has been designed and prototyped at the National Superconducting Cyclotron Laboratory for use in a heavy ion linac. The cavity is designed to provide 3.7 MV of accelerating voltage at an optimum beta = v/c = 0.53, with peak surface electric and magnetic fields of 32.5 MV/m and 79 mT, respectively. The resonant frequency is 322 MHz. The cavity was designed to reduce sensitivity to bath pressure fluctuations while maintaining a structure that can be easily fabricated, cleaned, and tuned. Deep draw forming dies and a copper cavity prototype were fabricated to confirm tolerances and formability. A prototype tuner was built; the helium vessel and power coupler have been designed. Measurements were performed to confirm finite element predictions for the mechanical modes, bath pressure sensitivity, tuner stiffness, and tuning range.
Muons, Inc, Batavia
JLAB, Newport News, Virginia
Funding: Supported in part by USDOE SBIR Grant DE-FG02-08ER85171
High-current RF cavities that are needed for many accelerator applications are often limited by the power transmission capability of the pressure barriers (windows) that separate the cavity from the power source. Most efforts to improve RF window design have focused on alumina ceramic, the most popular historical choice, and have not taken advantage of new materials. Alternative window materials have been investigated using a novel Merit Factor comparison and likely candidates have been tested for the material properties which will enable construction in the self-matched window configuration. Window assemblies have also been modeled and fabricated using compressed window techniques which have proven to increase the power handling capability of waveguide windows. Candidate materials have been chosen to be used in fabricating a window for high power testing at Thomas Jefferson National Accelerator Facility.
BARC, Trombay, Mumbai
Indian Institute of Technology Bombay, Mumbai
CERN, Geneva
An RF system model has been created for the CERN Linac2 Tanks. RF systems in this linac have both single and double feed architectures. The main elements of these systems are: RF power amplifier, main resonator, feed-line and the amplitude and phase feedback loops. The model of the composite system is derived by suitably concatenating the models of these individual sub-systems. For computational efficiency the modeling has been carried out in the base band. The signals are expressed in in-phase - quadrature domain, where the response of the resonator is expressed using two linear differential equations, making it valid for large signal conditions. MATLAB/SIMULINK has been used for creating the model. The model has been found useful in predicting the system behaviour, especially during the transients. In the paper we present the details of the model, highlighting the methodology, which could be easily extended to multiple feed RF systems.
BNL, Upton, Long Island, New York
Funding: US DOE
The National Synchrotron Light Source-II (NSLS-II) is a new ultra-bright 3GeV 3rd generation synchrotron radiation light source. The performance goals require operation with a beam current of 500mA and a bunch current of at least 0.5mA. The position and timing specifications of the ultra-bright photon beam imposes a set of stringent requirements on the radio Frequency (RF) control, among which, for example, is the 0.14 degree phase stability, and the flexibility of handling varying beam conditions. To meet these requirements, a digital implementation of the LLRF is chosen in order to be able to take the advantage of the power of precision signal processing and control that only DSP technology can provide. The initial design of NSLS II LLRF control solution is comprised of a FPGA-based basic field controller, a dual ASIC DSP co-processor directly coupled to the FPGA controller, as well as a local CPU which monitors the operation, stores the data, and facilitates the tests and development. The prototype of the basic FPGA field controller hardware has been designed. The first sample has been fabricated, and is currently being tested.
CEA, Gif-sur-Yvette
The acceleration of non relativistic particles, with a velocity lower than light velocity, in an RF cavity is more complex than for relativistic particles. Non-linear behaviours appear on the accelerator voltage because of the phase slippage inside the cavity. Moreover, a superconducting RF cavity is sensitive to various perturbations like mechanical vibrations (microphonics) and Lorentz force detuning. These perturbations produce a significant detuning of the cavity, leading a strong instability for the amplitude and phase of the field because of the narrow bandwidth of the accelerating mode. We will present a simulation approach of the cavity and its LLRF system control in order to ensure proper cavity operation under perturbations in the framework of the SPIRAL2 project.
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
NETS, Fuchu-shi
Upgrade of J-PARC linac has been planed using 972 MHz rf system. The rf field regulation is required to be less than ±1% in amplitude and ±1deg. in phase. The basic digital llrf concept is same as the present 324 MHz llrf system using a compact PCI crate. The main alterations are rf and clock generator (RF&CLK), mixer and IQ modulator (IQ&Mixer) and digital llrf algorithm. Since the typical decay time is faster (due to higher operational frequency than present 324 MHz cavity), chopped beam compensation is one of the main concerns. Performance of the digital feedback system using a cavity simulator is summarized.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
JAEA, Ibaraki-ken
In the J-PARC Linac LLRF, for the cavity warming-up, the cavity resonance is automatically tuned to be the accelerating frequency (324MHz and 972MHz) with a mechanical tuner installed on the cavity. Now we are planning to introduce a new method of the cavity-input frequency matching into the digital LLRF control system instead of the cavity resonance tuning for the cavity worming-up. For the frequency matching with the detuned cavity, the RF frequency is modulated by way of phase rotation with the I/Q modulator, while the source oscillator frequency is still fixed. The phase rotation is automatically controlled by the FPGA. The detuned frequency of the cavity is obtained from phase gradient of the cavity field decay at the RF-pulse end. No hardware modification is necessary for this frequency modulation method. The cost reduction or the high durability for the mechanical tuner is expected in the future. The results of the frequency modulation test will be reported in this presentation.
ORNL, Oak Ridge, Tennessee
The Spallation Neutron Source (SNS) has recently installed a prototype low level radio frequency (LLRF) control system for initial testing. This system is designed to replace the original fixed frequency, two harmonic Accumulator Ring LLRF system used to maintain a gap in the proton beam for extraction to the target. This prototype system is based on the hardware for the Linac LLRF system that has been modified to operate at the low frequencies required for the ring. The goal of the final system is to leverage the mature hardware and software of the Linac systems with the added flexibility needed to support the heavy beam loading requirements of the Accumulator Ring.
PAL, Pohang, Kyungbuk
SLAC, Menlo Park, California
In PAL, We are preparing the 3GeV Linac by upgrading the present 2.5GeV Linac and new 10GeV PxFEL project. The specification of the beam energy spread and rf phase is tighter than PLS Linac. In present PLS 2.5 GeV Linac, the specifications of the beam energy spread and rf phase are 0.6%(peak) and 3.5 degrees(peak) respectively. And the output power of klystron is 80 MW at the pulse width of 4 microseconds and the repetition rate of 10 Hz. In PxFEL, the specifications of the beam energy spread and rf phase are 0.1%(rms) and 0.1 degrees(rms) respectively. We developed the modulator DeQing system for 3GeV linac and PxFEL. And the phase amplitude detection system(PAD) and phase amplitude control(PAC) system is needed to improve the rf stability. This paper describes the microwave system for the PxFEL and the PAD and PAC system.
TRIUMF, Vancouver
The rf control system for the 1.3 GHz TRIUMF e-linac elliptical superconducting cavities is a hybrid analogue/digital design. It is based in part on an earlier design developed for the 1/4 wave superconducting cavities of the ISACII linac. This design has undergone several iterations in the course of its development. In the current design, down-conversion to an intermediate frequency of 138MHz is employed. The cavity operates in a self-excited feedback loop, while phase locked loops are used to achieve frequency and phase stability. Digital signal processors are used to provide amplitude and phase regulation, as well as mechanical cavity tuning control. This version also allows for the rapid implementation of operating firmware and software changes, which can be done remotely, if the need arises. This paper describes the RF control system and the experience gained in operating this system with a single-cavity test facility.
Warsaw University of Technology, Institute of Electronic Systems, Warsaw
DESY, Hamburg
One of the most important requirements for the XFEL RF system is to assure a very precise RF field stability within the accelerating cavities. The required amplitude and phase stability equals respectively dA/A <3·10-5, dphi<0.01 deg @ 1.3GHz in the injector and dA/A<10-3, dphi <0.1 deg @1.3GHz in the main linac section of the XFEL facility. Fulfilling such requirements is a very challenging task for the 1.5 km long main linac system and about 3.4 km length of the entire facility. Thousands of electronic and RF devices must be precisely phase synchronized for effective controlling of the RF field parameters. We describe the the proposed architecture of the RF Master Oscillator and the Phase Reference Distribution System for the XFEL. Design choices were based on the experience gained during the commissioning of the FLASH phase reference distribution system and on many laboratory experiments with distribution system components. Proposed system parameter analysis shows that the given requirements for the distributed signal phase stability can be fulfilled easily for the main linac section. Fulfilling the injector requirements may require using optical distribution techniques.
NSRRC, Hsinchu
The booster design of Taiwan Photon Source(TPS) has been significantly revised. Therefore, the transfer line from linac to booster(LTB) and the one from booster to storage ring(BTS) have been redesigned accordingly. The design of LTB transfer line has been simplified to reduce the number of magnets. The length of BTS transfer line has been greatly reduced. The design goal of transfer lines is to achieve high efficiency for beam injection. The status of current progress will be reported.
NTHU, Hsinchu
NSRRC, Hsinchu
The feasibility of generating sub-hundred femtosecond X-ray pulses based on inverse Compton scattering of relativistic electron pulses of 50-100 fsec with an 800 nm, 37.5 GW infrared Ti:Sapphire laser has been studied. The feasibility of generating sub-hundred femtosecond X-ray pulses based on head-on inverse Compton scattering (ICS) of relativistic electron pulses with laser has been studied. Relativistic electron pulses of 13.55 fsec can be produced by compressing the energy-chirped beam from a thermionic cathode rf gun with an alpha magnet *. This beam has an intensity of ~ 3.31x108 e- per bunch and is accelerated to 20.5 MeV with an S-band linac structure and is focused to 30 μm for scattering with an 800 nm, 3.75 mJ infrared Ti:Sapphire laser in the laser-beam interaction chamber. With this method, peak flux of back-scattered X-ray photons as high as 2.17x1018 photons/sec is achievable at ~ 1.24 Å wavelength. This femtosecond X-ray source is planned to be used as a tool for studying ultrafast phenomena in nanostructure in the near future.
*P. Kung, H.C. Lihn and H. Wiedemann, “Generation and Measurement of 50-fs (rms) Electron Pulses”, Phys. Rev. Lett. Vol.73, p.967-970, August 1994.
SAGA, Tosu
SAGA Light Source (SAGA-LS) is a 1.4 GeV synchrotron light source consisting of an injector linac and a storage ring of 75.6 m circumference. The SAGA-LS has been routinely operated with low emittance of 25 nm-rad since its official opening in February 2006. Machine improvements, including upgrades on the control system and grid pulsar for the injector linac, construction of a new septum magnet and beam monitor systems, and current increase from 100 to 200 mA, have been made in the past years. Along with the accelerator improvements, installation and development of new insertion devices have started. The SAGA-LS ring has six 2.5-m long straight sections available for insertion devices. A planar type undulator of Saga University is in operation. In addition, an APPLE-2 type undulator producing variably polarized light has been installed during the winter shutdown of 2008. In order to address user demand for high flux hard x-rays, design of a superconducting wiggler is under discussion. Construction of an experimental setup to produce MeV photons by the laser Compton scattering is in progress, preparing for precise beam energy measurement and user experiments in future.
LLNL, Livermore, California
SLAC, Menlo Park, California
LBNL, Berkeley, California
UCB, Berkeley, California
Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is under development at LLNL. High-brightness, relativistic electron bunches produced by the linac interact with a Joule-class, 10 ps laser pulse to generate tunable gamma-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status will be presented.
NSRRC, Hsinchu
NTHU, Hsinchu
A 266nm ultra-violet laser system has been installed as the drive laser of the NSRRC photoinjector. According to beam dynamic studies for the photoinjector, a 10ps uniform cylindrical beam will be generated at the Cu cathode to reduce emittance growth due to space charge and transverse RF fields in the photoinjector cavity. The main part of this system is diode laser pumped, 798nm regenerative IR amplifier that can provide 85fs pulse at 3.85mJ pulse energy. The conversion of frequency from IR to 266nm UV is achieved by a third harmonic generator. UV output pulse energy exceeds 300uJ. Synchronization between seed laser and the high power microwave system can be better than 1ps. In order to produce a uniform cylindrical beam for emittance reduction in the photoinjector, a refreactive UV beam shape and a pulse stacking temporal beam shape are being implemented.
SLAC, Menlo Park, California
Funding: Work supported by Department of Energy contract DE-AC03-76SF00515.
The beam stability for the Linac Coherent Light Source (LCLS) at SLAC is important for good X-Ray operation. Although most of the jitter tolerances are met, there is always room for improvement. Besides the short term pulse-to-pulse jitter, we will also discuss oscillation sources of longer time cycles from seconds (feedbacks), to minutes (cooling systems), and up to the 24 hours caused by the day-night temperature variations.
SLAC, Menlo Park, California
Funding: Work supported by Department of Energy contract DE-AC03-76SF00515.
The electron beam for the Linac Coherent Light Source (LCLS) at SLAC is accelerated by disk-loaded RF structures over a length of 1 km. The mainly longitudinal field can sometimes exhibit transverse components, which kick the beam in x and/or y. This is normally a stable situation, but when a klystron, which powers some of these structures, has to be switched off and another one switched on, different kicks can lead to quite a different orbit. Some klystrons, configured in an energy and bunch length feedback, caused orbit changes of up to 1 mm, which is about 20 times the σ beam size. The origins and measurements of these kicks and some efforts (orbit bumps) to reduce them will be discussed.
SLAC, Menlo Park, California
UCLA, Los Angeles, California
The Linac Coherent Light Source (LCLS) is an x-ray Free-electron Laser (FEL) being commissioned at SLAC. Recent beam measurements have shown that, using the LCLS injector-linac-compressors, the beam emittance is very small at 20 pC*. A similar low charge operation mode was also suggested and studied**. In this paper we perform start-to-end simulations of the entire accelerator including the FEL undulator and study the FEL performance versus the bunch charge. At 20 pC charge, these calculations associated with the measured beam parameters suggest the possibility of generating a longitudinally coherent single x-ray spike with 2-femtosecond duration at a wavelength of 1.5 nm. At ~100 pC charge level, our simulations show an x-ray pulse with 20 femtosecond duration and up to 1012 photons at a wavelength of 1.5 Å. These results open exciting possibilities for ultrafast science and single shot molecular imaging.
*A. Brachmann et. al., to be published.
**J. Rosenzweig et al., Nuclear Instr. and Meth. A 593, 39-44 (2008); S. Reiche et al., Nucl. Instr. And Meth. A 593, 45-48 (2008).
SLAC, Menlo Park, California
Funding: This work is supported by the Department of Energy contract DE-AC02-76SF00515.
LCLS capabilities can be significantly extended with a second undulator aiming at the soft x-ray spectrum (1- 5 nm). To allow for simultaneous hard and soft x-ray operations, 14 GeV beams at the end of the LCLS accelerator can be intermittently switched into the SLAC A-line (the beam transport line to End Station A) where the second undulator may be located. In this paper, we discuss the A-line optics design for transporting the high-brightness LCLS beams using the existing tunnel. To preserve the high brightness of the LCLS beams, special attentions are paid to effects of incoherent and coherent synchrotron radiation. Start-to-end simulations using realistic LCLS beam distributions are carried out.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
JAI, Oxford
Diamond, Oxfordshire
UMAN, Manchester
Cockcroft Institute, Warrington, Cheshire
A design for a free electron laser driver which utilises 1.3 GHz superconducting CW accelerating structures is studied. The machine will deliver longitudinally compressed electron bunches with repetition rates of 1 kHz with a possibility to increase up to 1 MHz. Tracking is performed from an NC RF photocathode gun, accelerating and compressing in three stages to obtain peak current greater than 1 kA at 2.2 GeV. This is achieved through injection at 200 MeV, then recirculating twice in a 1 GeV main linac. The optics design, optimisation procedures and start to end modelling of this system are presented.
ELETTRA, Basovizza
University of Nova Gorica, Nova Gorica
The second FEL line of the FERMI project was originally designed for providing long optical pulses (about 1ps) in the spectral range between 40 and 10 nm. Recent developments of both the FERMI scientific case and of new possible configurations of the FERMI linac stimulated a revision of the original setup in order to exploit new possibilities and fulfill requirements. In this work we deeply investigated the most relevant FEL configurations that may be implemented for the FERMI FEL2, showing that a revision of the original double-cascade high-gain harmonic generation is the most promising. According to numerical simulations, using the electron-beam parameters expected from the FERMI linac, the spectral range for FEL2 can now be extended down to 5 nm, and a significant amount of power can be produced also in the 1-nm spectral range. Moreover, the proposed setup is flexible enough for exploiting future developments of new seeding sources like HHG in gases.
RIKEN/SPring-8, Hyogo
The compact XFEL facility under construction in the SPring-8 campus aims at generation of SASE based XFEL at the wavelength of ~0.1 nm in 2010. Toward the smooth completion of the beam commissioning and achieving the reliable SASE XFEL operation, it is critically important to suppress the dark current upstream of the accelerator as much as possible. We thus investigated a removal scheme of the spatially diverged and energy deviated electrons forming the dark current by using sextupole magnets, which are installed over the C-band accelerating structures. The beam simulation showed that the combination of the distributed sextupole magnets with a small chicane, which locates in the adequate middle of the C-band accelerating structures, could efficiently remove the dark current emitted from the C-band acceleration structures. Here, we present the simulation results and the dark current suppression scheme designed for the compact XFEL facility at SPring-8.
UW-Madison/SRC, Madison, Wisconsin
SLAC, Menlo Park, California
The microbunching gain of a free-electron laser (FEL) driver is affected by the beam spreader that distributes bunches to the FEL beam lines. For the Wisconsin FEL (WiFEL), analytic formulas and tracking simulations indicate that a beam spreader design with a low value of R56 has little effect upon the gain.
UW-Madison/SRC, Madison, Wisconsin
SLAC, Menlo Park, California
The microbunching gain of the driver for the Wisconsin FEL (WiFEL) is reduced by more than an order of magnitude by using a single-stage bunch compressor rather than a two-stage design. This allows compression of a bunch with lower energy spread for improved FEL performance.
ANL, Argonne
Funding: Work at Argonne was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No DE-AC02-06CH11357.
The Linac Coherent Light Source (LCLS), now being commissioned at the Stanford Linear Accelerator Center (SLAC) in California, and coming online for users in the very near future, will be the world’s first x-ray free-electron laser user facility. Design and production of the undulator system was the responsibility of a team from the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). A sophisticated, five-axis, computer-controlled support and motion system positions and stabilizes all beamline components in the undulator system. The system also enables undulators to be retracted from the beam by 80 mm without disturbing the rest of the beamline components. An overview of the support and motion system performance, including achieved results with a production unit that was reserved at Argonne for this purpose, is presented.
INFN/LNF, Frascati (Roma)
SLAC, Menlo Park, California
The SuperB collider project aims at the construction of an asymmetric high luminosity B-Factory in the Tor Vergata University campus in Rome (Italy). The engineering aspects of the SuperB design and construction with the aim to reuse at maximum the PEP II components will be presented. Sinergies with the Italian FEL project SPARX, which will start civil construction this year, will be discussed. The two projects can share the Linac tunnel and other facilities. A study of ground motion will also be presented.
BNL, Upton, Long Island, New York
MIT, Middleton, Massachusetts
Funding: Work performed under US DOE contract DE-AC02-98CH1-886
Design of a medium energy electron-ion collider (MEeIC) is under development at Collider-Accelerator Department, BNL. The design envisions a construction of 4 GeV electron accelerator in a local area inside the RHIC tunnel. The electrons will be produced by a polarized electron source and accelerated in the energy recovery linac. Collisions of the electron beam with 100 GeV/u heavy ions or with 250 GeV polarized protons will be arranged in the existing IP2 interaction region of RHIC. The luminosity of electron-proton collisions at 1032 cm-2 s-1 level will be achieved with 40 mA CW electron current with presently available parameters of the proton beam. Efficient cooling of proton beam at the collision energy may bring the luminosity to 1033 cm-2 s-1 level. The important feature of the MEeIC is that it would serve as first stage of eRHIC, a future electron-ion collider at BNL with both higher luminosity and energy reach. The majority of the MEeIC accelerator components will be used for eRHIC.
CLASSE, Ithaca, New York
N.U, Nigde
We consider a scheme for gamma-gamma collisions at ILC. In our scheme the electron beam from 5 GeV injector-Linacs, present in ILC scheme, used in FEL amplifier. The laser radiation from solid-state laser amplified in this FEL and directed to nearby IP point for further Compton back scattering. Two additional ~50 m helical undulators and master laser system of intermediate power required for this scheme at ILC.
DESY, Hamburg
Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899.
The International Linear Collider (ILC) relies on very high beam powers and very small beam emittance to achieve the ambitious luminosity of 2·10+34 cm-2s-1. The potential for damage to the accelerator hardware in the event of some machine failure will require a sophisticated machine protection system. The small apertures in the Beam Delivery System (BDS) - specifically the collimators (by definition the smallest apertures in the machine) are particularly critical. Possible failures in the Main Linac of the ILC and their impact on the BDS are studied using the MERLIN C++ library*. We show that the machine is safe for at least one bunch in case of one of the described failures; a fast abort system is designed to safely extact the remainder of the bunches in the pulse to a dump. Investigated are phase and voltage shifts of the klystrons, quadrupole and corrector coil failures.
*Merlin - A C++ Class Library for Accelerator Simulations; http://www.desy.de/~merlin.
INFN/LNF, Frascati (Roma)
CERN, Geneva
The CLIC drive beam current, produced by the 1 GHZ fully loaded Linac, will be multiplied by a factor of 24 by the frequency multiplication system, to generate the high power beam representing the CLIC power source. The frequency multiplication system is composed by one delay loop plus two combiner rings. All rings will be isochronous, will contain trajectory tuning wigglers, and all magnets will be normal conducting. The design of the rings, with special emphasis on the rf deflectors characteristics, is presented.
SLAC, Menlo Park, California
CERN, Geneva
Funding: Work supported by the DOE under contract DE-AC02-76SF00515.
Plasma Wake-Field Acceleration (PWFA) has demonstrated acceleration gradients above 50 GeV/m. Simulations have shown drive/witness bunch configurations that yield small energy spreads in the accelerated witness bunch and high energy transfer efficiency from the drive bunch to the witness bunch, ranging from 30% for a Gaussian drive bunch to 95% for bunch with triangular shaped longitudinal profile. These results open the opportunity for a linear collider that could be compact, efficient and more cost effective than the present microwave technologies. A concept of a PWFA-based Linear Collider (PWFA-LC) has been developed by the PWFA collaboration. Here we will describe the conceptual design and optimization of the drive beam, which includes the drive beam linac and distribution system. We apply experience of the CLIC drive beam design and demonstration in the CLIC Test Facility (CTF3) to this study. We discuss parameter optimization of the drive beam linac structure and evaluate the drive linac efficiency in terms of the drive beam distribution scheme and the klystron / modulator requirements.
SLAC, Menlo Park, California
Funding: This work is supported by the Department of Energy contract DE-AC02-76SF00515.
FACET is a proposed facility at SLAC National Accelerator Laboratory for beam driven plasma wakefield acceleration research. It is proposed to be built in the SLAC linac sector 20, where it will be separated from the LCLS located downstream and will gain the maximum beam energy from the upstream two kilometers of linac. FACET will also include an upgrade to linac sector 10, where a new e+ compressor chicane will be installed. The sector 20 will require a new optics consisting of two chicanes for e+ and e- bunch length compression, a final focus system and an extraction line. The two chicanes will allow the transport of e- and e+ bunches together, their simultaneous compression and proper positioning of e+ bunch behind e- at the plasma Interaction Point (IP). For a minimal cost, the new optics will mostly use the existing SLAC magnets. The desired beam parameters at the IP are: up to 23 GeV beam energy, 2·1010 charge per bunch, 10 micron round beam spot without dispersion and 25 micron bunch length. Details of the FACET optics design and results of particle tracking simulations are presented.
Muons, Inc, Batavia
Fermilab, Batavia
Intense muon beams have many potential applications. However, muons originate from a tertiary process that produces a diffuse swarm. To make useful beams, the swarm must be rapidly collected and cooled before the muons decay. A promising new concept for the collection and cooling of muon beams to increase their intensity and reduce their emittances is investigated: the use of a nearly isochronous helical cooling channel (HCC) to facilitate capture of the muons into a few RF bunches. Such a distribution could be cooled quickly and then coalesced efficiently into a single bunch to optimize the luminosity of a muon collider. An analytical description of the method is presented followed by simulation and optimization studies. Practical design constraints and integration into a collider, neutrino factory or intense beam scenario are discussed and plans for further studies are addressed.
Muons, Inc, Batavia
JLAB, Newport News, Virginia
ODU, Norfolk, Virginia
Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86351
We have previously considered the application of fast pulsing quadrupoles to increase the focusing of muon beams as they gain energy in the linac region of a recirculating linear accelerator (RLA) in order to allow more passes. In this work we consider the use of pulsed magnets, both quads and dipoles, to reduce the number of beam lines needed for the return arcs of the RLA. We investigate the required relationships between the linac parameters (length and energy gain) and the momentum acceptance of the return arcs and consider the optimum strategy for accelerating both muon charge signs.
ODU, Norfolk, Virginia
JLAB, Newport News, Virginia
Muons, Inc, Batavia
BNL, Upton, Long Island, New York
Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86351
Recirculating linear accelerators (RLA) are the most likely means to achieve the rapid acceleration of short-lived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. One problem is that in the simplest schemes, a separate return arc is required for each passage of the muons through the linac. In the work described here, a novel arc optics based on a Non Scaling Fixed Field Alternating Gradient (NS-FFAG) lattice is developed, which would provide sufficient momentum acceptance to allow multiple passes (two or more consecutive energies) to be transported in one string of magnets. With these sorts of arcs and a single linac, a Recirculating Linear Accelerator (RLA) will have greater cost effectiveness and reduced losses from muon decay. We will develop the optics and technical requirements to allow the maximum number of passes by using an adjustable path length to accurately control the returned beam phase to synchronize with the RF.
JLAB, Newport News, Virginia
Muons, Inc, Batavia
Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86351
Neutrino Factories and Muon Colliders require rapid acceleration of short-lived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses International Linear Collider (ILC) RF structures can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the RF cavities, leading to greater cost effectiveness. We discus the optics and technical requirements for RLA designs, using RF cavities capable of simultaneous acceleration of both μ+ and μ- species, with pulsed Linac quadrupoles to allow the maximum number of passes.
DESY, Hamburg
ANL, Argonne
Fermilab, Batavia
KEK, Ibaraki
Funding: Work at Argonne supported by U.S. Department of Energy, Office of Science, office of Basic Energy, Sciences, under Contract No. DE-AC02-06CH11357
XFEL and ILC both intend to accelerate long beam pulses of a few thousand bunches and high average current. It is expected that the superconducting accelerating cavities will eventually be operated close to their respective gradient limits as they are pushed to higher energies. In addition, a relative energy stability of <10-4 must be maintained across all bunches. These parameters will ultimately push the limits of several sub systems including the low-level rf control, which must properly compensate for the heavy beam loading while avoiding problems from running the cavities close to their quench limits. An international collaboration led by DESY has begun a program of study to demonstrate such ILC-like conditions at FLASH, which serves as a prototype for both XFEL and ILC. The objective is to achieve reliable operation with pulses of 2400 3-nC bunches spaced by 330 ns (a current of 9 mA) while meeting the required energy stability and while operating accelerating cavities close to their quench limits. Other goals include measurement of cryoload from HOM heating and evaluation of rf power overhead for the ILC. The paper will describe the program and report recent results.
KEK, Ibaraki
The e+/e- injector LINAC in KEK usually successively injects into four rings, which are Low Energy Ring (LER) of KEKB (3.5GeV/e+), High Energy Ring (HER) of KEKB (8.0GeV/e-), Photon Factory (PF) (2.5GeV/e-) and Advanced Ring for pulse X-rays (PF-AR) (3.0GeV/e-). While LINAC continuously injects into LER and HER alternatively every about five minutes, keeping both of KEKB rings almost their full operating currents. It takes about one minute to switch beam mode of LINAC. PF and PF-AR are injected a few times in a day. Time for PF or PF-AR including mode-switch had taken about 20 minutes for each other. For PF injection, the switching time was shortened in 2005 and the occupancy time is about 5 minutes. In 2008, we succeeded to make the switching time shorter, 2 seconds for HER/LER, and Pulse-to-pulse alternatively injection for PF/HER using an event system. Especially for KEKB, the short switching time is contributed to provide high currents and to improve luminosity at which beam lives are too short to keep the high currents. In 2009, we have a plan to inject also for LER/HER pulse-to-pulse alternatively.
IKP, Mainz
Funding: Work supported by DFG (CRC443) and the German Federal State of Rheinland-Pfalz
In December 2006 the maximum output energy of the cw race track microtron cascade MAMI B was increased to 1508MeV by the successful commissioning of the world wide first Harmonic-Double-Sided-Microtron (HDSM)* as a new fourth stage. Since then MAMI C was in operation for more than 15000 hours, delivering approx. 10000 hours the maximum beam energy of 1508MeV. We will report about our operational experiences and the recent machine developments concerning e.g. the increase of the energy and stabilisation of the output energy down to 10-6. Topics of machine reliability and stability will be addressed and the operation under different demands of nuclear physics experiments described.
*K.-H. Kaiser et al., NIM A 593 (2008) 159 - 170, doi:10.{10}16/j.nima.2008.05.018
UPC, Barcelona
MSU, Moscow
EPSC, CASTELLDEFELS
CIEMAT, Madrid
Elytt Energy, Madrid
A compact race-track microtron (RTM) with the maximal output energy 12 MeV is under construction at the Universitat Politècnica de Catalunya (UPC) in collaboration with the Skobeltsyn Institute of Nuclear Physics of the Moscow State University, CIEMAT and a few Spanish industrial companies and medical centers. The RTM end magnets are four-pole systems with the magnetic field created by a rare-earth permanent magnet material. As a source of electrons a 3D off-axis electron gun is used. These elements together with a C-band accelerating structure, dipole magnets, which allow to extract the electron beam with energy from 6 MeV to 12 MeV in 2 MeV step, and a focusing quadrupole are placed inside a vacuum chamber. We report on the current status of the technical design and results of tests of some of the components.
CLASSE, Ithaca, New York
Funding: Work supported by NSF, New York State, and Cornell University
A cryomodule design for the Cornell Energy Recovery Linac (ERL) will be based on TTF technology, but must have several unique features dictated by the ERL beam parameters. The main deviations from TTF are that the HOM loads must be on the beamline for sufficient damping, that the average power through the RF couplers is low, and that cw beam operation introduces higher heat loads. Several of these challenges were addressed for the Cornell ERL Injector, from which fabrication and operational insight was gained. A baseline design for the Cornell ERL Linac cryomodule will be presented that includes fabrication and operational considerations along with thermal and mechanical analyses.
NSRRC, Hsinchu
The feasibility of SRF operation at 2K using the remaining refrigeration capacity of an operating 4.5K cryogenic plant at NSRRC is examined. A refrigeration configuration with warm compression is proposed under an assumption that a reasonable amount of cryogenic heat load is required at 2K. The expectation of the efficacy of the cold and warm heat exchangers (HEX) is evaluated in terms of the corresponding equivalent cryogenic heat load on the 4.5K cold box. A factor approximately 9.5 or 6.0 is required to convert the cryogenic loss, 12 W at 2K, into our 4.5K cold box operated in a refrigeration mode without or with the cold heat exchanger (efficiency 85 %), respectively. An additional benefit is that the required volumetric pumping speed of the warm compressor can be greatly decreased. Moreover, a considerable cold capacity from the sub-atmospheric cold return helium gas can be ultimately converted by combining the cold HEX working together with a highly effective warm HEX, to a conversion factor 3.8 with an efficiency 95 %. Special attention must be devoted to minimize the risk of contamination or impurity for a turbine refrigerator.
JAI, Oxford
We review the current status of the collimation system of the Compact Linear Collider (CLIC). New calculations are done to study the survivability of the CLIC energy spoiler in case of impact of a full bunch train considering the most recent beam parameters. The impact of the collimator wakefields on the luminosity is also studied using the updated collimator apertures, and we evaluate the beam position jitter tolerance that is required to preserve the nominal luminosity. Moreover, assuming the new collimation depths, we evaluate the collimation efficiency.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
JAI, Oxford
The postlinac energy collimation system of the Compact Linear Collider (CLIC) protects the machine by intercepting mis-steered beams due to possible failure modes in the linac. The collimation is based in a spoiler-absorber scheme. The mission of the spoiler is to protect the main downstream absorber by dispersing the beam, via multiple Coulomb scattering, in case of a direct hit. We present the design of energy spoilers for CLIC, considering the following requirements: spoiler survival to the deep impact of an entire bunch train, and minimisation of spoiler wakefield effects during normal operation. Different configurations of the spoiler are studied in order to achieve an optimum performance.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
CERN, Geneva
Linac4 is a 160 MeV H- linac which will replace the existing Linac2, a 50 MeV proton linac, at CERN as a first step of the upgraded LHC proton injector chain. No collimation system is foreseen in the baseline design but it will become mandatory for opreation at highest duty cycle in order to reduce activation of the machine. Such a system will also help to reduce activation at low duty cycle. A review of different collimation options, initial studies on collimator designs capable of intercepting beam power of 10, 25 and 50 Watts at energies between 50 and 160 MeV, the activation of such designs and the downstream elements are shown in this paper.
ELETTRA, Basovizza
Funding: The work was supported in part by the Italian Ministry of University and Research under grant FIRB-RBAP045JF2.
The FERMI@elettra electron beam dump is designed for a 1nC, 1.8 GeV, 50Hz repetition rate beam. Using GEANT simulations, materials are chosen to absorb 99% of the beam energy and to limit the radio-isotope production. In addition, from the energy deposition distribution inside the dump, the thermal load is estimated. The necessary requirements, the design and the expected performance are presented and discussed.
Euclid TechLabs, LLC, Solon, Ohio
Coating Technology Solution, Inc., Somerville
ANL, Argonne
Funding: This work is supported by the US Department of Energy
There has been considerable progress in using microfabrication techniques to produce experimental rf sources. These devices have for the most part been based on micromachined copper surfaces or silicon wafers. We are developing THz diamond wakefield structures produced using Chemical Vapor Deposition (CVD) technology. The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric rf structures: high breakdown voltage (~600 MV/m), extremely low dielectric losses and the highest thermoconductive coefficient available for removing waste heat from the device. These structures are based on cylindrical diamond dielectric tubes that are manufactured via a relatively simple and inexpensive chemical vapor deposition (CVD) process, plasma assisted CVD. Use of the CVD process is a much simpler method to achieve high quality rf microcavities compared to other microfabrication techniques. We are designing a number of diamond rf structures with fundamental TM01 frequencies in the 0.1-1 THz range. Numerical simulations of planned experiments with these structures will be reported.
CERN, Geneva
NSC/KIPT, Kharkov
IN2P3 IPNL, Villeurbanne
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
LAL, Orsay
ANL, Argonne
KEK, Ibaraki
HU/AdSM, Higashi-Hiroshima
BNL, Upton, Long Island, New York
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
The CLIC polarized positron source is based on a positron production scheme in which polarized photons are produced by Compton process. Compton backscattering happens in a so-called "Compton ring" where an electron beam of 1.06 GeV interacts with a powerful laser beam amplified in an optical resonator. The circularly-polarized gamma rays are sent on to a target, producing pairs of longitudinally polarized electrons and positrons. An Adiabatic Matching Device maximizes the capture of the positrons. A normal-conducting 2 GHz Linac accelerates the beam up to 2.424 GeV before injection into the Pre-Damping Ring (PDR). The nominal CLIC bunch population is 4.4x109 particles per bunch. Since the photon flux coming out from a "Compton ring" is not sufficient to obtain the requested charge, a stacking process is required in the PDR. Another option is to use a "Compton Energy Recovery Linac" where a quasi-continual stacking in the PDR could be achieved. A third option is to use a "Compton Linac" which would not require stacking. We describe the overall scheme as well as advantages and constraints of the three different options.
Imperial College of Science and Technology, Department of Physics, London
Fermilab, Batavia
The International Design Study for the Neutrino Factory (IDS-NF), which is being carried out by personnel from the Americas, Asia, and Europe, has been established by the Neutrino Factory community to deliver a Reference Design Report for the facility by 2012*. The baseline design, developed from that defined in the ISS**, will provide 1021 muon decays per year from 25GeV stored muon beams. The facility will serve two neutrino detectors; one situated at source-detector distance of between 3000-5000km, the second at 7000-8000km. Muon storage rings have also been proposed as the basis of a multi-TeV lepton-antilepton Muon Collider. The R&D required to deliver the Neutrino Factory and that required to realise the Muon Collider have many synergies including: the pion-production target; ionisation cooling; rapid acceleration of large emittance beams; and the provision of high-gradient accelerating cavities that operate in high magnetic fields. The conceptual design of the accelerator facility for the Neutrino Factory and the relation of the IDS-NF to the EUROnu Design Study will be described***.
*The decision point identified by the Strategy Group of the CERN Council.
**The International Scoping Study for a future Neutrino Factory and super-beam facility.
***Submitted on behalf of the IDS-NF.
SLAC, Menlo Park, California
UCLA, Los Angeles, California
Duke University, Durham, North Carolina
USC, Los Angeles, California
Funding: Work supported in part by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
An electron beam driven Plasma Wake-Field Accelerator (PWFA) has recently sustained accelerating gradients above 50GeV/m for almost a meter. Future experiments will transition from using a single bunch to both drive and sample the wakefield, to a two bunch configuration that will accelerate a discrete bunch of particles with a narrow energy spread and preserved emittance. The plasma works as an energy transformer to transform high-current, low-energy bunches into relatively lower-current higher-energy bunches. This method is expected to provide high energy transfer efficiency (from 30% up to 95%) from the drive bunch to the accelerated witness bunch. The PWFA has a wide variety of applications and also has the potential to greatly lower the cost of future accelerators. We discuss various possible uses of this technique such as: linac based light sources, injector systems for ring based synchrotron light sources, and for generation of electron beams for high energy electron-hadron colliders.
UCLA, Los Angeles, California
BNL, Upton, Long Island, New York
The novel and revolutionary concept of VLA proof of principle is described in this paper. The simulation with the current BNL-ATF parameter shows that electron beam can get net energy from intense laser beam. The initial 20 MeV electron beam with energy spread of 0.001 can get hundreds of keV energy gain with energy spread of 0.010 by interacting with a laser a0=1. BNL-ATF's spectrometer can tell 0.0001 accuracy of energy spread and distinguish 0.001 accuracy energy spread. The proposal has been approved by BNL-ATF and the experiment for this proof of principle is going to be scheduled.
IHEP Beijing, Beijing
CSNS accelerator mainly consists of an H- linac and a proton rapid cycling synchrotron. It is designed to accelerate proton beam pulses to 1.6 GeV kinetic energy at 25 Hz repetition rate, striking a solid metal target to produce spallation neutrons. The accelerator is designed to deliver a beam power of 120 kW with the upgrade capability up to 500 kW, The CSNS accelerator is the first large-scale, high-power accelerator project to be constructed in China and thus we are facing a lot of challenges in some key technologies. A series of R&D for major prototypes have being conducted since 2006, including an H- ion source, DTL tank, RF power supply for the linac, injection/extraction magnets and its pulse power supplies, dipole and quadrupole prototype magnets in the ring and its power supplies, ferrite-loaded RF prototype cavity, ceramic vacuum chamber, control and some beam diagnostics. This paper will briefly introduce the design and R&D status of the CSNS accelerator.
POSTECH, Pohang, Kyungbuk
Funding: Work supported by MEST and PAL.
Recently the Korean government successfully completed a large-scale facility, called the KSTAR, a fully superconducting tokamak after joining in the ITER project. It made renewed interests in large-scale scientific facilities to promote basic and applied research capabilities. The next projects include a space project and particle accelerators. The immediate one in accelerator program is the PLS-upgrade, and its budget is now in the congress for FY2009. The others are in the middle of consensus making process: a heavy ion accelerator for rare isotopes and a new synchrotron light source other than the PLS-upgrade and the ongoing proton linac program. This paper will give an overview of the status and prospects of major particle accelerator initiatives in Korea. The paper will also include descriptions of the significant contributions undertaken by Korea through collaborations with major international facilities using particle accelerators. Finally, the paper will outline how industry, government and universities in Korea are collaborating on particle accelerator R&D.
RRCAT, Indore (M.P.)
Particle accelerator programs being pursued by the Indian labs cover a broad range, encompassing accelerators for nuclear physics research (NPR) (in the low and intermediate energy range), construction of synchrotron radiation sources (SRS) as well as participation in international accelerator projects, especially those related to high energy physics. Machines for NPR include 14MV Pelletrons, augmented by home built superconducting linac boosters to enhance the energy & mass range of the ion beams, and a superconducting cyclotron which is currently undergoing commissioning at Kolkata. Two SRS, namely, a 450 MeV ring Indus-1 and 2.5 GeV booster cum light source, Indus-2, have been indigenously constructed and set up at Indore. A program is also on to develop a high current proton accelerator that will eventually be used for R&D linked to ADS. Regarding our international collaborations, Indian labs have contributed to setting up of LHC at CERN, are associated with the CLIC Test Facility 3 & Linac-4 and the FAIR project at Hamburg besides working with Fermilab on ILC/Project-X R&D. The talk will give an overview of some of the recent developments related to these activities.
CERN, Geneva
The path towards a multi-TeV e+e- linear collider proposed by the CLIC study is based on the Two Beam Acceleration scheme. Such a scheme is promising in term of efficiency, reliability and cost. The rationale behind the two-beam scheme is discussed in the paper, together with the special issues related to this technology and the R&D needed to demonstrate its feasibility.
SLAC, Menlo Park, California
Funding: Work supported by the U.S. Dept. of Energy contract #DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) is a SASE 1.5-15 Å x-ray Free-Electron Laser (FEL) facility under construction at SLAC, and presently in an advanced phase of commissioning. The injector, linac, and new bunch compressors were commissioned in 2007 and 2008, establishing the necessary electron beam brightness at 14 GeV. The final phase of commissioning, including the FEL undulator and the long transport line from the linac, began in November 2008, with first 1.5-Å FEL light and saturation observed in mid-April 2009. We report on the accelerator, undulator, and FEL operations, although prior to the availability of the full x-ray diagnostics suite, which will not be ready until June 2009.
JLAB, Newport News, Virginia
Funding: Work supported by the Office of Naval Research, the Joint Technology Office, the Commonwealth of Virginia, the Air Force Research Laboratory, and by the DOE Contract DEAC05-84ER40150.
As the only currently operating free electron laser (FEL) based on a CW superconducting energy recovering linac (ERL), the Jefferson Laboratory FEL Upgrade remains unique as an FEL driver. The present system represents the culmination of years of effort in the areas of SRF technology, ERL operation, lattice design, high power optics and DC photocathode gun technology. In 2001 the FEL Demo generated 2.1 kW of laser power. Following extensive upgrades, in 2006 the FEL Upgrade generated 14.3 kW of laser power breaking the previous world record. The FEL Upgrade remains a valuable testbed for studying a variety of collective effects, such as the beam breakup instability, longitudinal space charge and coherent synchrotron radiation. Additionally, there has been exploration of operation with lower injection energy and higher bunch charge. Recent progress and achievements in these areas will be presented, and two recent milestones installation of a UV FEL and establishment of a DC gun test stand will be discussed. Additionally, a review of the longitudinal matching scheme and the use of incomplete energy and its implications will be presented.
PAL, Pohang, Kyungbuk
The Pohang Accelerator Laboratory (PAL) celebrated its 20th anniversary this year. After the completion of the Pohang Light Source (PLS) construction in 1994, the PLS started user service with two beamlines in 1995. The PLS energy was 2.0 GeV. The first major upgrade of the PLS had been done from 2000 to 2002, in which operation energy of the PLS was increased from 2.0 GeV to 2.5 GeV. The number of beamlines has been steadily increased since the start of user service. The number of beamlines currently in service is 28. Three beamlines are under construction. Number of users and performed experiments in 2007 were respectively 2553 and 837. Average impact factor of published papers is over 3.0, which is one of the best among Korean research institutes. Based on such success, the PAL is pursuing the second upgrade plan, called the PLS-II. The PLS will be upgraded its energy from 2.5 GeV to 3.0 GeV. With the upgrade, it will be possible to construct ten more insertion devices. The brightness of the PLS-II will be more than a order higher compared to the current PLS. In this presentation, details of the PLS-II project will be introduced.
This work was supported by the MEST (Ministry of Education, Science and Technology) and the POSCO (POhang iron and Steel making COmpany) in Korea.
INFN/LNF, Frascati (Roma)
Istituto Nazionale di Fisica Nucleare, Milano
CEA, Gif-sur-Yvette
INFN-Roma II, Roma
ENEA C.R. Frascati, Frascati (Roma)
SOLEIL, Gif-sur-Yvette
INFN-Roma, Roma
University of Tehran, Tehran
UCLA, Los Angeles, California
The SPARC project foresees the realization of a high brightness photo-injector to produce a 150-200 MeV electron beam to drive 500 nm FEL experiments in SASE, Seeding and Single Spike configurations. The SPARC photoinjector is also the test facility for the recently approved VUV FEL project named SPARX. The second stage of the commissioning, that is currently underway, foresees a detailed analysis of the beam matching with the linac in order to confirm the theoretically prediction of emittance compensation based on the “invariant envelope” matching , the demonstration of the “velocity bunching” technique in the linac and the characterisation of the spontaneous and stimulated radiation in the SPARC undulators. In this paper we report the experimental results obtained so far. The possible future energy upgrade of the SPARC facility to produce UV radiation and its possible applications will also be discussed.
ANL, Argonne
Fermilab, Batavia
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The latest version of PTRACK*, the parallel version of the beam dynamics code TRACK, is capable of simulating a very large number of particles (a billion or more). In the case of the Fermilab 8-GeV H-minus linac, it is possible to simulate the actual number of particles in the bunch. Taking advantage of this capability we are revisiting our original beam loss studies**, but this time with larger statistics and including a new process of beam loss which is the stripping of H- ions. TRACK has recently been updated*** with the possibility of stripping H- by three different processes, namely black body radiation, Lorentz force stripping and residual gas interactions. Results of ideal end-to-end simulations (no errors) with the actual number of particles in a beam bunch (860M) as well as error simulations for different sets of errors with 10M and eventually 100M particles per seed will be presented and discussed. These simulations are being performed on Argonne's new petascale computing facility "BG/P".
* J. Xu et al, Proceedings of HB-2008.
** P. Ostroumov, B. Mustapha and V.A. Aseev, Proceedings of Linac-06.
*** J.-P. Carneiro, B. Mustapha and P. Ostroumov, submitted to PRST-AB.
CEA, Gif-sur-Yvette
The 250 mA, 40 MeV cw deuteron beam required for the International Fusion Materials Irradiation Facility (IFMIF) will be provided by two 125 mA linacs. In order to accelerate the beam from 5 MeV to 40 MeV, a superconducting linac, housed in four cryomodules, is proposed. The design is based on two beta families (beta=0.094 and beta=0.166) of half-wave resonators (HWR) at 175 MHz. The transverse focusing is achieved using one solenoid coil per lattice. This paper presents the extensive multi-particle beam dynamics simulations that have been performed to adapt the beam along the SC-HWR structure in such a high space charge regime. As one of the constraints of the IFMIF linac is hands-on maintenance, specific optimizations have been done to minimize the beam occupancy in the line (halo). A Monte Carlo error analysis has also been carried out to study the effects of misalignments or field imperfections.
CEA, Gif-sur-Yvette
INFN/LNL, Legnaro (PD)
CIEMAT, Madrid
The two IFMIF (International Fusion Materials Irradiation Facility) accelerators will each have to deliver 5 MW of deuteron beam at 40 MeV. To validate the conceptual design, a prototype, consisting of one 9 MeV accelerator called EVEDA (Engineering Validation and Engineering Design Activity), is being constructed. Beam dynamics studies are entering the final phase for the whole EVEDA and for the accelerating part of IFMIF. The challenging point is to be able to reconcile the very strong beam power and the hands-on maintenance constraint. At energies up to 5 MeV, difficulties are to reach the requested intensity under a very strong space charge / compensation regime. Over 5 MeV, difficulties are to make sure that beam losses can be maintained below 10-6 of the beam intensity. This paper will report the strategies and choices adopted in the optics design and the beam measurement proposal.
GSI, Darmstadt
IHEP Beijing, Beijing
In the conventional design of rf linacs, the space-charges are not in three-dimension thermal equilibrium. The space-charge couples the longitudinal and transverse will cause equipartitioning process which causes the emittance growth and the halo formation. In the design of the Chinese Spallation Neutron Source (CSNS) linac], three cases are investigated using the Hofmann stability charts to analysis and optimize the layout. In this paper, we present the equipartitioning beam study of the CSNS Alvarez DTL linac.
IAP, Frankfurt am Main
Funding: * Work supported by BMBF contr. No. 06F134I & EU contr. No. EFDA/99-507ERB5005CT990061
The International Fusion Materials Irradiation Facility (IFMIF) is looking for an efficient drift-tube linac (DTL) which can accelerate a 125mA, CW deuteron beam from 5MeV to 40MeV with a high beam quality and nearly no beam loss. Taking advantages of the KONUS dynamics concept and the H-type structure, a compact DTL design has been realized by IAP, Frankfurt University, with satisfying performances. Including simulated errors, the feasibility of the IAP scheme has been carefully checked as well.
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A high-brightness electron beam used for linac-based fourth-generation light sources such as X-ray free-electron lasers (FELs) and energy recovery linacs (ERLs) is often non-Gaussian distributed especially in the longitudinal direction. In order to study the intra-beam scattering effect (IBS) in such a beam, we added a slice analysis method to elegant. This paper explains this method and an application result to a possible ERL upgrade of the Advanced Photon Source.
UMAN, Manchester
It is necessity to be able to accurately predict the performance of the any proposed baseline accelerator design in which the effects of couplers, trapped modes, Wakefields, realistic machining and alignment errors as well as numerous other important effects have been taken into consideration. Traditionally used numerical schemes (such as Finite element and Finite difference) require vast resources and time, not only that but the inclusion of realistic defects and misalignments into the baseline configuration will prove time consuming as it will potentially require remeshing of the problem. Here we present a mode matching scheme which utilises a globalised scattering matrix approach that allows large scale electromagnetic field calculations to be obtained rapidly and efficiently. The scalar product of all the S matrices used within this paper has been determined analytically and is calculated only once per transition, adding to the efficiency of the calculation. The influence of cell misalignments and cavity perturbations on the main accelerating linacs of XFEL and CLIC are exhibited. The wake-fields in super-structures and segments of entire modules are also presented
CLASSE, Ithaca, New York
Funding: This work was supported by the National Science Foundation.
The theories of beam loss and emittance growth by Touschek and intra-beam scattering formulated for beams in storage rings have recently been extended to linacs. In most linacs, these effects are not relevant, but they become important in Energy Recovery Linacs (ERLs) not only because of their large current, but also because the deceleration of the spent beam increases the relative energy deviation and transverse oscillation amplitude of the scattered particles. In this paper, we describe a methodology for designing a collimator scheme to control where scattered particles are lost. The methodology is based on Touschek particle generation and tracking simulations implemented in {\tt BMAD}, Cornell's beam dynamics code. The simulations give the locations where scattering occurs and the locations where the scattered particles are lost. The simulations are used to determine the trajectory of the scattered particles, which are analyzed to determine optimal locations for collimators.
G.H. Gillespie Associates, Inc., Del Mar, California
A PARMILA 2 Module has been developed for the Particle Beam Optics Laboratory (PBO Lab). PARMILA 2 is a FORTRAN program used to both design and simulate radiofrequency ion linear accelerators. The program can be used to design radiofrequency accelerators that include drift tube linac (DTL) structures, coupled cavity linac (CCL) structures, coupled-cavity drift tube linac (CC-DTL) structures, and superconducting accelerator structures. PARMILA 2 can also be used to simulate beams in these structures and in transport lines that with magnetic, radiofrequency and electrostatic beam optics elements. PBO Lab provides a sophisticated graphic user interface (GUI) for multiple optics codes. From the same familiar interface users can run TRANSPORT, TURTLE, MARYLIE, TRACE 3-D and DECAY-TURTLE. PARMILA 2 now joins this suite of optics codes available as PBO Lab Modules. New PBO Lab tools have been developed to assist users in utilizing different optics codes to simulate and validate the performance of an accelerator designed with PARMILA 2. An overview of the new PARMILA 2 module and associated new tools is presented and some of the GUI features are illustrated.
IUCF, Bloomington, Indiana
Funding: This work is supported by AFOSR under grant FA9550-08-1-0160.
We present the theoretical and numerical results of a dispersion free time-dependent Green's function method which can be utilized for calculating electromagnetic space-charge fields due to arbitrary current in a conducting pipe. since the Green's function can be expanded in terms of solutions to the wave equation, the numerical solutions to the fields also satisfy the wave equation yielding a completely dispersion free numerical method. This technique is adequately suited for modeling bunched space-charge dominated beams, such as those found in high-power microwave sources, for which the effects of numerical grid dispersion and numerical Cherenkov radiation are typically found when using FDTD type methods.
INFN/LNF, Frascati (Roma)
High gain free electron lasers require the production of a high brightness electron beam that is a low emittance, high current beam. To this aim the injector and linac design and theirs operation are the leading edge. The successful operation of the SCSS FEL driven by a C-band linac has demonstrated that C-band is a mature technology and it is very attractive in terms of gradient and compactness. In this paper it is described a beam dynamics study, made with the Homdyn code, for a C-band linac driven FEL with S-band photo-injector. The key point is to match the longitudinal phase space of the S-band photo-injector with the C-band linac using the velocity bunching technique. The result is a brightness up to 1015A/m2, obtained with a low emittance and a relaxed peak current.
JAI, Oxford
The alignment of the next generation of linear accelerators will be much more critical than that of currently existing machines. This is especially true for very long machines with ultra low emittance beams; such as the ILC and CLIC. The design and study of such machines will require a large number of simulations. However; full simulation of misalignment currently requires computer programs which are very resource intensive. A model which can be used to rapidly generate reference networks with the required statistical properties will be presented. The results for emittance growth in the ILC main linac using the model with Dispersion Matched Steering (DMS) applied are also shown.
ANL, Argonne
Transition radiation is frequently used to determine the time profile of a bunched relativistic particle beam. Emphasis is usually given to diagnostics sensitive to wavelengths in the infrared-to-optical portion of the spectrum. In this study, CST Particle Studio simulations are used to make quantitative statements regarding the low-frequency (DC to microwave) behavior of coherent transition radiation from a mirror inclined at 45 degrees relative to the particle beam trajectory. A moving Gaussian bunch confined within a cylindrical beam pipe is modeled. Simulation results are presented.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) injector consists of a linac, a particle accumulator ring (PAR), and a booster synchrotron (booster). The PAR accumulates multiple linac bunches and compresses them into a single bunch for booster injection. Beam energy in the PAR is 325 MeV. Due to its low energy and relatively strong beam-loading effect, beam charge and phase (or timing ) monitoring is critical to the stable operations of rf control loops. We implemented a monitor system with an FPGA processor, which provides both current monitor and stripline fast waveforms. The system provides a bunch charge reading with a data rate of up to 1 MHz and a beam phase resolution of 200 ps, which are sufficient for the rf phase control loops. The system is currently used for beam tuning and diagnostics during normal operation. We are planning to build an upgraded version with fast data output and included it in the new rf control loops. We present a description of the system and the measurement results.
BNL, Upton, Long Island, New York
The effects of high fluences of energetic charged particles on CdZnTe detectors have been studied and are reported in this paper. Specifically, 200 MeV protons of the Brookhaven National Laboratory LINAC were used to bombard a set of CdZnTe detector crystals to fluences as high as 2.6x1016 protons/cm2. Following exposure a set of past-irradiation analyses were conducted to quantify the effects. These include (a) gamma-ray spectra analysis using a high-purity germanium detector in an effort to assess both the peak position shifting as a function of fluence and the spectral content, (a) resistivity and leakage current measurements, and (c) manifestation of radiation damage in the crystal microstructure. In addition, and based on the irradiation parameters used, a numerical prediction model was formulated aiming to benchmark the observed isotopes.
CEA, Gif-sur-Yvette
The probe beam linac of the CTF3 test facility, named CALIFES, is developed by the CEA Saclay, the LAL Orsay and CERN to deliver short bunches (0.75 ps) with a charge of 0.6 nC to the CLIC 12 GHz accelerating structures. To setup the machine and obtain a precise beam handling, six high resolution beam position monitors (BPMs), based on a radiofrequency reentrant cavity with an aperture of 18 mm, are installed along the linac. The associated electronics is composed of an analog signal processing electronics with a multiplexing to control the six monitors. Due to mechanical tolerances, dipole mode frequencies are different for each BPMs, 100 MHz IF frequency is, therefore, used so that monitors operate in single and multi-bunches. Digitalised signals from acquisition boards are made available to the operation crew thanks to the OASIS interfaces. In this paper, the BPMs acquisition and the signal post processing, to extract the beam position, will be discussed and first beam tests will be presented.
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
The ALBA Linac is a turn-key system able to produce 4 nC electron beams at 100 MeV beams with a normalized emittance below 30 mm*mrad. Beam position stability below 0.1 mm is measured using new BPM electronics. Thorough analysis are carried out to measure the beam emittance, energy and energy spread. This paper discusses the measurement techniques, analysis method, and results obtained during the Linac commissioning.
CERN, Geneva
BNL, Upton, Long Island, New York
Graz University of Technology (TUG), Signal Processing and Speech Communication Laboratory (SPSC), Graz
In particle accelerators coaxial cables are commonly used to transmit wideband beam signals covering many decades of frequencies over long distances. Those transmission lines often have a corrugated outer and/or inner conductor. This particular construction exhibits a significant amount of frequency dependent group delay variation. A comparison of simulations based on theoretical models and S11 and S21 network analyzer measurements up to 2.5 GHz is presented. It is shown how the non-linear phase response and varying group delay leads to ringing in the pulse response and subsequent distortion of signals transmitted through such coaxial transmission lines.
CERN, Geneva
CIEMAT, Madrid
In the framework of EUROTeV, a Precision Beam Position Monitor (PBPM) has been designed, manufactured and tested. The new PBPM, based on the inductive BPM presently used in the CERN Clic Test Facility (CTF3), aims to achieve a resolution of 100 nm and an accuracy of 10μm in a 6 mm aperture. A dedicated test bench has been designed and constructed to fully characterize and optimize the PBPM. This paper describes the final design, present the test bench results and reports on the beam tests carried out in the CERN CTF3 Linac.
Fermilab, Batavia
ANL, Argonne
Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The challenge of mitigating the strong enhancements of the optical transition radiation (OTR) signal observed after bunch compression in the Advanced Photon Source (APS) linac chicane and at the Linac Coherent Light Source (LCLS) has recently been addressed. We have demonstrated a technique to mitigate the intensity of the coherent OTR (COTR) relative to the OTR signals on the APS beams at 325 MeV. Since the previously reported spectral content of the COTR at LCLS after the first compression stage is similar, the concepts should also apply to LCLS. We utilized the stronger violet content at 400 nm of the OTR compared to the observed gain factors of the COTR in the blue to NIR regime. We also demonstrated the use of an LSO:Ce scintillator that emits violet light to support lower-charge imaging. Spectral-dependence measurements of the COTR were done initially at the 325-MeV station using a series of band pass filters inserted before the CCD camera, but recent tests with an Oriel spectrometer with ICCD readout have extended those studies and confirmed the concepts. These techniques are complementary to the proposed use of a laser heater to mitigate the microbunching itself at LCLS.
IUCF, Bloomington, Indiana
Fermilab, Batavia
The proton ion source for the High Intensity Neutrino Source (HINS) Linac front-end at Fermilab has been successfully commissioned. It produces a 50 keV, 3 msec beam pulse with a peak current greater than 20 mA at 2.5 Hz. The beam is transported to the radio-frequency quadrupole (RFQ) by a low energy beam transport (LEBT) that consists of two focusing solenoids, four steering dipole magnets and a beam current transformer. To understand beam transmission through the RFQ, it is important to characterize the 50 keV beam before connecting the LEBT to the RFQ. A wire scanner and a Faraday cup are temporarily installed at the exit of the LEBT to study the beam parameters. Beam profile measurements are made for different LEBT settings and results are compared to those from computer simulations. In lieu of direct emittance measurements, a solenoid variation method based on profile measurements is used to reconstruct the beam emittance.
IFIC, Valencia
Funding: FPA 2007-31124-E (MICINN)
A set of two Inductive Pick-Up (IPU) prototypes with its associated electronics for Beam Position Monitoring in Test Beam Line (TBL) in the 3rd CLIC Test Facility (CTF3) at CERN were designed, constructed, characterized and tested by the IFIC. One of these two prototypes is already mounted in the first module of the TBL line for testing with beam. In the first part of this paper we described the first tests performed with beam in the prototype. The second part of this paper is dedicated to the description of the construction, performance characterization and installation of a series of 15 units, including its respective mechanical supports in the complete TBL line in spring 2009.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
JAEA/LINAC, Ibaraki-ken
In the J-PARC LINAC, BPMs with 4 strip lines (up, down, right, left) have been used to monitor the beam position by taking log ratio of signals on the opposite (facing) sides of stirp lines. We are studying possibility to monitor beam phase by measuring phase of summed signal of all four stlip lines. In this paper, status of the study is presented.
IKP, Mainz
Funding: Work supported by DFG (CRC 443) and the German Federal State of Rheinland-Pfalz.
The 1.5GeV Harmonic Double Sided Microtron (HDSM)* as the fourth stage of the Mainz Microtron (MAMI) is now in routine operation for two and a half years**. Simulations predicted a wide range of applicable longitudinal parameters with which the machine can be run. Measurements of the longitudinal acceptance proved that. The reproducibility of different configurations is sufficient to support a fast and reliable set-up of the machine and to guarantee a stable long-term operation. But in order to optimise the configuration a reliable measurement of the phases and accelerating voltages in both linacs is essential. Each turn’s phase information is provided by low-Q-TM010 resonators at both linacs when operating the machine with 10ns diagnostic pulses. The HDSM’s four bending magnets are designed with a field gradient to compensate the vertical fringe defocusing. The decreasing field integral results in less synchronous energy gain per turn, automatically causing a change of the longitudinal phase. The calibration of the phase signals which in case of the RTMs could be easily done by exciting a synchrotron oscillation was improved to deliver precise phase data.
*K.-H. Kaiser et al., NIM A 593 (2008) 159 - 170, doi:10.{10}16/j.nima.2008.05.018
**A. Jankowiak et al., ID 2689, this conference
JAI, Oxford
University of Oxford, Clarendon Laboratory, Oxford
University of Oxford, Oxford
INFN/LNF, Frascati (Roma)
OXFORDphysics, Oxford, Oxon
Diamond, Oxfordshire
Funding: John Adams Institute, University of Oxford John Fell Fund, University of Oxford
We describe a method that uses a modified pepper-pot design to measure in a single shot the emittance of electron beams with energies above 100 MeV. Our setup consists of several thin layers of tantalum with spacers in between to leave slits through which the electron beam can be sampled. We report on a measurement done using this method at the DAΦNE BTF with a 508 MeV electron beam.
LANL, Los Alamos, New Mexico
Funding: This work is supported by the United States Department of Energy under contract DE-AC52-06NA25396
Precise measurement of the tunes in the Los Alamos Proton Storage Ring (PSR) is difficult because the beam is normally extracted immediately after accumulation, preventing the use of continuous-wave radio frequency measurements. Presented here is a method that takes advantage of the phase information in the response of the beam to a transverse oscillatory driving voltage. This technique offers much greater precision than using the amplitude spectrum alone.
LANL, Los Alamos, New Mexico
Funding: US Department of Energy
Future improvements to the Los Alamos Neutron Scattering Center (LANSCE) include new Beam position and phase measuring systems that operate at 201.25 to 805 MHz. An effort is underway to build and test prototype electronics for these applications. We plan to use direct down conversion to 35 to 115 MHz followed by COTS FPGA hardware for in-phase and quadrature-phase (I/Q) signal processing. Self- calibration and system diagnostics circuits will be included. We are reporting on the status of these efforts.
CERN, Geneva
The CLIC components will have to be pre-aligned within a tolerance of 10 microns over a sliding window of 200m all along the linacs, before injecting the first beam. Such tolerance is about 30 times more demanding than for the existing machines as the SPS and LHC; it is a technical challenge and a key issue for the CLIC feasibility. In order to define the CLIC alignment strategy from the survey and beam dynamics point of view, simulations have been undertaken concerning the propagation error due to the measurement uncertainties of the pre-alignment systems. The uncertainties of measurement, taken as hypotheses for the simulations, are based on the data obtained on several dedicated facilities. This paper introduces the facilities and the latest results obtained, as well as the simulations performed.
JAEA/J-PARC, Tokai-mura
KEK, Ibaraki
JAEA/LINAC, Ibaraki-ken
JAEA, Ibaraki-ken
Over hundred beam loss monitors (BLM) in the J-PARC LINAC have been used to measure the beam loss observed during the accelerator operation. Dose rates distributed in LINAC area were compared with beam loss records taken by the BLMs. This paper describes the results of the operational data and their comparisons with the dose rates of LINAC area.
ORNL, Oak Ridge, Tennessee
BINP SB RAS, Novosibirsk
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
A transverse phase space emittance scanner is proposed and under development for the 1-GeV H- SNS linac, using a laser beam as a slit. For a 1 GeV H- beam, it is difficult to build a slit because the stopping distance is more than 50 cm in copper. We propose to use a laser beam as an effective slit by stripping off the outer electron of the H- (making it neutral) upstream of a bend magnet and measuring the stripped component downstream of the bend magnet. The design and modeling of the system will be discussed. We are expecting to make a preliminary measurement in 2009.
Ankara University, Faculty of Engineering, Tandogan, Ankara
CERN, Geneva
Funding: Turkish Atomic Energy Authority
CLIC study aims at a center-of-mass energy for electron-positron collisions of 3TeV using room temperature accelerating structures at high frequency (12GHz) which are likely to achieve 100 MV/m gradient. Due to conventional high frequency RF sources do not provide sufficient RF power for 100MV/m gradient, CLIC relies upon a two-beam-acceleration concept: The 12GHz RF power is generated by a high current electron beam (Drive Beam) running parallel to the main beam with deceleration in special Power Extraction Structures (PETS) and the generated RF power is transferred to the main beam. In order to obtain very high RF power at 12GHz frequency, injected beam into PETS should have 2.37GeV energy, 101A pulse current and pulse length around 240ns. Drive beam accelerator (DBA) accelerates the beam up to 2.37GeV in almost fully-loaded structures and the pulse after DBA contains more than 70000 bunches, has a length around 140μs and 4.2A pulse current. After some modifications in delay loop and in combiner rings the beam has 101A pulse current and 240ns pulse length. In this study simulations of some transverse beam parameters for different options for the lattice of the DBA are presented.
ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The corrective steering algorithm in TRACK has been recently updated to be more realistic. A simplified formalism will be presented along with the method of implementation. As an important application, the algorithm was used to determine the number of correctors and monitors required for the front-end of the HINS project at Fermilab. The algorithm allowed us also to find the optimum locations for the correctors and monitors as well as the required corrector field strength and the required monitor precision for an effective correction. This correction procedure could be easily implemented in an accelerator control-room for real-time machine operations.
BNL, Upton, Long Island, New York
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
As part of the efforts to increase polarization and luminosity in RHIC during polarized proton operations we have modified the injection optics and stripping foil geometry in the AGS Booster in order to reduce the emittance growth during H- injection. In this paper we describe the modifications, the injection process, and present results from beam experiments.
IHEP Beijing, Beijing
CERN, Geneva
A new design of the 6.6GeV Booster linac for CLIC which is based on the FODO lattice is presented in this note. Particle tracking studies using PLACET [1] are performed in order to estimate the single-bunch and multi-bunch emittance growth. First, the studies of optics are introduced. Then, the sing-bunch effects and multi-bunch effects are studied in the last two part of this note.
UMAN, Manchester
CERN, Geneva
The upgrade of the normal conducting REX-ISOLDE heavy ion accelerator at CERN, under the HIE-ISOLDE framework, proposes the use of superconducting (SC) quarter-wave resonators (QWRs) to increase the energy capability of the facility from 3 MeV/u to beyond 10 MeV/u. A beam dynamics study of a lattice design comprising SC QWRs and SC solenoids has confirmed the design's ability to accelerate ions, with a mass-to-charge ratio in the range 2.5 < A/q < 4.5, to the target energy with a minimal emittance increase. We report on the development of this study to include the implementation of realistic fields within the QWRs and solenoids. A preliminary error study is presented in order to constrain tolerances on the manufacturing and alignment of the linac.
CLASSE, Ithaca, New York
The production of ultra-short x-rays in Cornell's Energy Recovery Linac (ERL) requires electron bunch lengths of less than 100fs with minimal transverse emittance growth and energy spread. Because the linac consists of two sections separated by an arc, CSR forces limit the bunch length in the linac, and bunch compression has to be installed after acceleration. Creation of such short bunches requires a second order bunch compression scheme with correction of the third order dispersion. In this paper, we discuss possible bunch compression systems and explore the benefits of each using the tracking program TAO including CSR forces. Overall, we find that a FODO compressor utilizing dipole, quadrupole and sextupole magnets can achieve the design goals of the short pulse mode.
DESY, Hamburg
The post-linac collimation system should simultaneously fulfil several different functions. In first place, during routine operations, it should remove with high efficiency off-momentum and large amplitude halo particles, which could be lost inside undulator modules and become source of radiation-induced demagnetization of the undulator permanent magnets. The system also must protect the undulator modules and other downstream equipment against mis-steered and off-energy beams in the case of machine failure without being destroyed in the process. From beam dynamics point of view, the collimation section should be able to accept bunches with different energies (up to ± 1.5% from nominal energy) and transport them without deterioration not only of transverse, but also of longitudinal beam parameters. In this article we present the optics solution for the post-linac collimation system which fulfils all listed above requirements.
CERN, Geneva
At present, for most LHC type physics beams, six buckets of the PS operated with harmonic number h=7 are filled in two transfers, and each of the PS Booster rings provides only one bunch. The scheme presented aims at replacing the double batch transfer by a single batch transfer and is of interest (i) for the nominal 25 ns LHC beams once the Booster injection energy has been increased after completion of Linac4 and (ii) already now for 50 ns and 75 ns LHC beams less demanding for the Booster in terms of beam brightness. Two bunches with the correct spacing must be generated in the Booster rings by superposition of an h=2 RF system and a smaller h=1 component. Theoretical considerations and first experimental results will be presented.
CERN, Geneva
The motivation for the construction of CERN Linac4 is to improve the performance of the PSB by raising the injection energy and implementing a new H- charge exchange multiturn injection scheme. Strategies to design the H- charge exchange injection hardware and, in particular, to mitigate perturbations of the lattice will be reported and the proposed geometry described.
CERN, Geneva
The proposed new CERN injector chain LINAC4, SPL, PS2 will require the construction of new beam transfer lines. A preliminary design has been performed for the 4 GeV SPL to PS2 H- transfer line. The constraints, beam parameters and geometry requirements are summarised and a possible layout proposed, together with the magnet specifications. First considerations on longitudinal beam dynamics and on beam loss limitations from H- lifetime are presented.
CERN, Geneva
In the main linac of the compact linear collider (CLIC) the beam induced wakefield and dispersive effects will be strong. In the paper the reference beam-based alignment procedure for the new CLIC parameters is specified and the resulting tolerances for static imperfections are detailed.
CERN, Geneva
In the compact linear collider (CLIC) the tolerances on dynamic imperfections are tight in the main linac. In particular the limited beam delivery system bandwidth requires very good RF phase and amplitude stability. Transverse motion of the beam line components is also of concern. The resulting tolerances are detailed in the paper.
CERN, Geneva
Uppsala University, Uppsala
Fermilab, Batavia
Prior to acceleration in the main linac, the particle beams created in the centrally located injector have to be transported to the outer ends of the CLIC site. This transport should not only preserve the beam quality but also shape, characterize and tune the phase space distribution to match the requirements at the entrance of the main linac. Hence, the performance of the transport downstream of the damping rings up to the main linac, the so called RTML, is crucial for the overall performance of CLIC. The RTML consists of a variety of components like bunch compressors, accelerating cavities, spin rotators, collimators, diagnostics sections, feedback and feedforward systems, each serving a distinct function. We discuss the different parts of the RTML and the beam dynamics challenges connected to them. Their status is outlined and results of beam dynamics simulations are presented.
KEK, Ibaraki
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
MHI, Kobe
The output energy of J-PARC linac is planned to be upgraded from 181 MeV to 400 MeV by adding an ACS (Annular Coupled Structure linac) section. The debuncher system for J-PARC linac is also replaced in this energy upgrade. The new debuncher system will consist of two 972-MHz debuncher cavities with the separate-function configuration. In this configuration, the momentum jitter is corrected with the first debuncher, whereas the momentum spread is controlled with the second debuncher. This configuration is advantageous in simplifying the tuning procedure, and it is also beneficial in reducing the nonlinear effects of the debuncher cavities. In this paper, the beam dynamics design of the debuncher system is presented with some simulation results.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
KEK, Ibaraki
Wire Scanner Monitors (WSMs) and Bunch Shape Monitors (BSMs) are going to be installed in the entrance part of ACS (Annular Coupled Structure) section at the energy upgraded J-PARC linac. WSMs are used to measure transverse beam profiles, and BSMs are used to measure longitudinal beam profiles. Both are used to match beams from upstream SDTL (Separated-type Drift Tube Linac) accelerator cavities to ACS. Only a BSM will be installed in the beggining and the best location for the BSM has been chosen through studies of the tuning schemes.
NSCL, East Lansing, Michigan
LBNL, Berkeley, California
Funding: U.S. Department of Energy
A driver linac has been designed for the proposed Facility for Rare Isotope Beam (FRIB) at Michigan State University. FRIB is a lower cost and reduced scope alternative to the Rare Isotope Accelerator (RIA) project. The superconducting driver linac will accelerate stable isotope beams to energies ≥200 MeV/u with a beam power up to 400 kW for the production of rare isotope beams. The driver linac consists of a front-end and two segments of superconducting linac connected by a charge stripping station. End-to-end beam simulation studies with high statistics have been performed using the RIAPMTQ and IMPACT codes on high performance parallel computers. These studies include misalignment of beam elements, rf amplitude and phase errors for cavities, and thickness variation of the stripping foil. Three-dimensional fields of the superconducting solenoids and cavities were used in the lattice evaluation. The simulation results demonstrate good driver linac performance. No uncontrolled beam losses were observed even for the challenging case of multiple charge state uranium beam acceleration. The beam dynamics issues will be discussed and the detail beam simulation results presented.
ORNL, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The Spallation Neutron Source (SNS) linac system is designed to deliver 1 GeV pulsed H- beams up to 1.56 MW for neutron production. As beam power was increased from 10 kW to 660 kW in less than three years, beam loss in the accelerator systems particularly in the superconducting linac (SCL), became more significant. In the previous studies, unexpected beam loss in the SCL was mainly attributed to longitudinal problems. However, our most recent simulations have focused on beam transverse effects. These include multipole components from magnet imperfections and dipole corrector windings of the linac quadrupoles. The effect of these multipoles coupled with other errors will be discussed.
TRIUMF, Vancouver
DAE/VECC, Calcutta
TRIUMF proposes a 1/2 MW electron linac (e-linac) for radioactive ion beam production via photofission. The e-linac is to operate CW using 1.3 GHz superconducting (SC) technology. The accelerator layout consists of a 100 keV thermionic gun, a normal conducting buncher, an injector module, and main linac modules accelerating to a final energy of 50 MeV. The design beam current is 10 mA. The beam dynamics of the injector, where electrons make the transition to the fully relativistic state, has been identified as the most critical part of the design and is the subject of simulations (starting at the gun cathode) using realistic EM fields in PARMELA and TRACK. CW operation demands the novel choice of adopting an SC capture section. A preliminary design of the injector foresees a capture section composed either of two independent or two coupled single-cell cavities, beta <1, that increase the energy to about 500 keV, followed by one nine-cell cavity that boosts the energy up to 10 MeV. The design parameters are subjected to a global optimization program. In this paper we present results from the beam dynamics study as well as details and final outcome of the optimization process.
Northern Illinois University, DeKalb, Illinois
Euclid TechLabs, LLC, Solon, Ohio
ANL, Argonne
Funding: This work is supported by the U.S. Department of Energy under contract no. DE-FG02-06ER41435 with Northern Illinois University.
We present a diagnostics suite and analyze techniques for setting up the longitudinal beam dynamics in ILC e- injectors and e+ and e- bunch compressors. Techniques to measure the first order moments and recover the first order longitudinal transfer map of the injector's intricate bunching scheme are presented. Coherent transition radiation diagnostics needed to measure and monitor the bunch length downstream of the ~5 GeV bunch compressor are investigated using a vector diffraction model.
ORNL, Oak Ridge, Tennessee
BINP SB RAS, Novosibirsk
Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
Conversion of BLM readings into number of lost particles is a challenging task. Any insertion device is a good mean to obtain a localized loss and obtain such conversion factor with direct measurement. Such a measurement serves as a good benchmark for Monte-Carlo simulation of radiation transport. We used wire scanners and scraper induced losses to perform analysis of BLM response to local loss. The paper also provides a technique to measure 0.1% of full beam charge being intercepted by scraper during 650kW production run extracting the useful signal from high noise (20 times higher than signal) environment
SLAC, Menlo Park, California
Funding: Work supported by U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) begins operation this year with 83 new stripline beam position monitor (BPM) processors. System requirements include several-micron position resolution for single-bunch beam charge of 200 pC. We describe the processing scheme, system specifications, commissioning experience, and performance measurements.
USP/LAL, Sao Paulo
Funding: FAPESP, CNPq
In this work we describe the design of the OTR monitors that will be used to measure beam parameters of the IFUSP Microtron electron beam. The OTR monitor design must allow for efficiency in the entire energy range (from 5 MeV up to 38 MeV in steps of 0.9 MeV), and the devices are planed to monitor charge distribution, beam energy and divergence. An exception is made for the OTR monitor to the 1.7 MeV beam line, which is to be used to monitor only the beam charge distribution at the exit of the linac injector. The image acquisition system is also presented.
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
Funding: Supported by the EU under contract PITN-GA-2008-215080
Beam diagnostics is a rich field in which a great variety of physical effects are made use of and consequently provides a wide and solid base for the training of young researchers. Moreover, the principles that are used in any beam monitor or detector enter readily into industrial applications or the medical sector which guarantees that training of young researchers in this field is of relevance far beyond the pure field of particle accelerators. DITANET- "DIagnostic Techniques for particle Accelerators a European NETwork" - covers the development of advanced beam diagnostic methods for a wide range of existing or future accelerators, both for electrons and ions. DITANET is the largest ever coordinated EU education action for PhD students in the field of beam diagnostic techniques for future particle accelerators with a total budget of 4.2 M. This contribution gives an overview of the network’s activities and outlines selected research results from the consortium.
UMD, College Park, Maryland
ANL, Argonne
Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office.
Single foil OTR and two foil OTR interferometry have been successfully used to measure the size and divergence of electron beams with a wide range of energies. To measure rms emittance, two cameras are employed: one focused on the foil to obtain the spatial distribution of the beam, the other focused to infinity to obtain the angular distribution. The beam is first magnetically focused to a minimum size in directions which are orthogonal to the propagation axis, using a pair of quadrupoles. Then simultaneous measurements of the rms size (x,y) and divergence (x’,y’) of the beam are made. However, in the process of a quadrupole scan, the beam can go through a spot size minimum, a divergence minimum and a waist, i.e. the position where the cross-correlation term is zero. In general, the beam size, divergence and focusing strength for each of these conditions are different. We present new algorithms that relate the beam and magnetic parameters to the rms emittance for each of these three cases. We also compare the emittances, obtained using our algorithms and measurements made at the ANL AWA facility, with those produced by computer simulation.
USTC/NSRL, Hefei, Anhui
The strip-line beam position monitor can be used as a non-intercepting emittance measurement monitor. The most important part of emittance measurement is to pick up the quadrupole component. To improve the accuracy of measurement, the response of the strip-line BPM pickups will be mapped before it’s installed in the HLS LINAC. This paper introduce the calibration system of the BPM, which consists of a movable antenna and a RF signal source, simulating the beam , a BPM moving bench with its control system, and an electronics system. When the position calibration is done first, the offset between electronic center and mechanical one of the BPM and the position sensitivity are gotten. There are two methods for quadrupole component calibration: one is indirect evaluation method that estimates the sensitivity of quadrupole component by the factor of position second moment; the other is direct method by simulation of a Gaussian beam through together many Gaussian weighted grid points. The results of two methods are given and compared. The effect of antenna’s diameter upon the fitting size of simulate beam has also been analyzed.
USTC/NSRL, Hefei, Anhui
Funding: National “985 Project” （173123200402002); National Natural Science Foundation(10875117)
A new high brightness injector is planned to be installed at HLS, NSRL. It is based on a new photocathode RF electron gun. To steer the beam along the optimal trajectory, higher precision controlling of beam position is required. The positional resolution of the BPM system designed for the new RF gun should be higher than 10 μm. A new cavity BPM design is then given instead of old stripline one because of its higher positional resolution. In a normal symmetrical pill-box BPM design, machining tolerance will result in x-y coupling, which will cause cross-talk problem. A novel design is then presented here. To solve the problem before, a position cavity which has a racetrack cross section is used instead of a pill-box one. The ideal resolution of this design could be less than 3 nm.
ELETTRA, Basovizza
DEEI, Trieste
Funding: The work was supported in part by the Italian Ministry of University and Research under grant FIRB-RBAP045JF2.
Travelling wave and standing wave deflectors are well known RF devices that nowadays are used in particle accelerators as a beam diagnostic tool. They will also be implemented in FERMI@Elettra project, a soft X-ray fourth-generation light source under development at the ELETTRA laboratory, and used to completely characterize the beam phase space by means of measurements of bunch length and transverse slices emittance. In particular, one deflector will be placed at low energy (250MeV) and another at high energy (1.2GeV), just before the FEL process starts. In this note we collect our experience and simulation on this last device, making a comparison between the most relevant options we have considered to satisfy our RF and space constraints. Basic cell design is discussed for both the travelling and standing wave choice. In particular, two different modes, the 2/3π and the 5/6π, are analyzed for the travelling wave option while an 11 cells design in π mode is presented for the standing wave case. For both cases sensitivity analysis and other relevant RF parameters are given.
SLAC, Menlo Park, California
Funding: Work supported by U.S. Department of Energy under Contract Nos. DE-AC02-06CH11357 and DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) project at SLAC uses a dense 15 GeV electron beam passing through a 131m undulator to generate extremely bright xrays. The project requires electron bunches with a bunch charge of 20pC to 1nC and bunch lengths of 0.020mm (70fs).To measure the beam resolution to 1 micron (rms) for bunch charge > 20 pC in the undulator, a cavity BPM system was chosen. This system can measure the beam position to within a micron. The LCLS Cavity BPM local oscillator subsystem consists of a second order phase-locked loop (PLL) to synchronize with LCLS timing system and injector system. The output of the PLL is distributed to 36 Cavity BPM receivers and 36 high speed digitizers while maintaining good phase noise and low jitter. This paper describes the design of the PLL and how it met the design specifications of 0.1 degree of phase noise at 119MHz and 1 ns of rms jitter.
JLAB, Newport News, Virginia
Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Jefferson Lab’s CEBAF accelerator operation requires various frequency signals to be distributed along the site. Three signals: 10 MHz, 70 MHz and 499 MHz are synthesized in the Machine Control Center (MCC) while 1427 MHz and 429 MHz are derived from 499 MHz and 70 MHz signals in four separate locations. We are replacing our obsolete 10 MHz, 70 MHz and 499 MHz sources with new sources that will incorporate a GPS receiver to discipline a 10 MHz reference. In addition the MO (Master Oscillator) system will be redundant (duplicate MO) and a third signal source will be used as a system diagnostic. Moreover the 12 GeV Energy Upgrade for CEBAF accelerator will be adding 80 new RF systems. To support them the distribution of 1427 MHz and 70 MHz signals has to be extended and be able to deliver enough LO (Local Oscillator) and IF (Intermediate Frequency) power to 320 old and 80 new 80 RF systems. This paper discusses the new MO and the drive line extension.
TUB, Beijing
BNL, Upton, Long Island, New York
Synchronization between a laser system and an electron beam plays a critical role in photoinjector operation, pump-probe experiments and many other applications. Here we report two novel experimental techniques for measuring the laser to RF timing jitter in a photoinjector, and e-beam arrival timing jitter after a magnetic chicane bunch compressor. The laser to RF timing jitter was characterized by observing the electron beam charge fluctuation through the Schottky effect. This technique was used to characterize the SDL photoinjector laser to RF timing jitter as a function of the temperature fluctuation in the laser room, and we have shown the resolution of this technique is ~100 fs. A stripline beam position monitor (BPM) located down stream of the compressor will be used to investigate the e-beam arrival timing jitter after a magnetic chicane bunch compressor; the outputs of the stripline BPM can be used to measure the arrival timing jitter by mixing them with a RF reference signal. The effect of the chicane on the arrival time jitters will be studied for the first time using this technique.
CERN, Geneva
The CLIC study is exploring the scheme for an electron-positron collider with a centre-of-mass energy of 3 TeV in order to make the multi-TeV range accessible for physics. The current goal of the project is to demonstrate the feasibility of the technology by the year 2010. Recently, important progress has has been made concerning the high-gradient accelerating structure tests and the experiments with beam in the CLIC test facility, CTF3. On the organizational side, the CLIC international collaborations have significantly gained momentum considerably boosting the CLIC study.
CERN, Geneva
The aim of the last CLIC test facility CTF3, built at CERN by an international collaboration, is to prove the main feasibility issues of the CLIC two-beam acceleration technology. The main points which CTF3 should demonstrate by 2010 are the generation of a very high current drive beam and its use to efficiently produce and transfer RF power to high-gradient accelerating structures. To prove the first point a delay loop and a combiner ring have been built, following a linac, in order to multiply the current by a factor two and four, respectively. The power generation and transfer and the high gradient acceleration are instead demonstrated in the CLIC experimental area (CLEX), where the drive beam is decelerated in special power extraction structures(PETS). In this paper we describe the results of the combination in the ring, properly working after the cure of the vertical instability which limited high current operation, and the commissioning of the new beam lines installed in the second half of 2008, including response matrix analysis and dispersion measurements used to validate the optics model. The results of the energy transfer will be also briefly described.
MIT, Middleton, Massachusetts
There are presently three initiatives for a hadron-lepton collider in the world: eRHIC at BNL, ELIC at JLab (both part of the EIC collaboration), and LHeC at CERN. This talk presents the status of these initiatives and compares their different thrusts in physics research as well as in their approach to the facility design, pointing out the strengths and limits of each particular proposal.
CERN, Geneva
N.U, Nigde
Cockcroft Institute, Warrington, Cheshire
Ankara University, Faculty of Sciences, Tandogan/Ankara
The University of Liverpool, Liverpool
KEK, Ibaraki
TOBB ETU, Ankara
BNL, Upton, Long Island, New York
Sub-atomic physics at the energy frontier probes the structure of the fundamental quanta of the Universe. The Large Hadron Collider (LHC) at CERN opens for the first time the “terascale” (TeV energy scale) to experimental scrutiny, exposing the physics of the Universe at the sub-attometric (~10-19 m, 10-10 as) scale. The LHC will also take the science of nuclear matter to hitherto unparalleled energy densities (low-x physics). The hadron beams, protons or ions, in the LHC underpin this horizon, and also offer new experimental possibilities at this energy scale. A Large Hadron electron Collider, LHeC, in which an electron (positron) beam of energy (70 to 140 GeV) is in collision with one of the LHC hadron beams, makes possible terascale lepton-hadron physics. The LHeC is presently being evaluated in the form of two options, “ring-ring” and “linac-ring”, either of which operate simultaneously with pp or ion-ion collisions in other LHC interaction regions. Each option takes advantage of recent advances in radio-frequency, in linear acceleration, and in other associated technologies, to achieve ep luminosity as large as 1033 cm-2s-1.
Fermilab, Batavia
Funding: Work supported by the Fermi Research Alliance, under contract to the U. S. Department of Energy
As the Fermilab Collider program draws to a close, a vision has emerged of an experimental program built around the high intensity frontier. The centerpiece of this program will be a new 8 GeV superconducting H- linac which will support world leading programs in long baseline neutrino experimentation and the study of rare processes. Based on technology shared with the International Linear Collider, Project X will support the generation of multi-MW beams at 60-120 GeV from the Main Injector, simultaneous with several hundred kilowatts at 8 GeV from the Recycler. Project X will also open the possibility of a future energy frontier facility based on utilization as the front end of a muon storage ring based facility.
Omega-P, Inc., New Haven, Connecticut
Columbia University, New York
Yale University, Beam Physics Laboratory, New Haven, Connecticut
NSC/KIPT, Kharkov
Funding: US Department of Energy, Office of High Energy Physics, Advanced Accelerator R & D.
A rectangular two-beam dielectric wakefield accelerator (DWA) module is described which, when energized by a 14 MeV, 50 nC drive bunch moving in one channel, is shown to deflect a test bunch which originates from an independent source moving in a parallel channel. We show that such a module, 30 cm in length, can deflect transversely a 1 GeV electron by ~ 1 mrad in 1 ns, after which a following bunch can pass undeflected. Apparatus required to accomplish this task consists of a laser-cathode RF gun and an optional linac to generate the drive bunch. The associated DWA components could be used for kicker applications in a storage ring or a more energetic electron linear accelerator. An example we describe is tailored to a DWA demonstration project underway at the Argonne Wakefield Accelerator, but the design can be altered to allow for changes including a lower-energy but still relativistic drive bunch. The kicker, through appropriate design, can deflect one out of several bunches in a storage ring, leaving the remaining bunches essentially unaffected by the structure.
GANIL, Caen
The SPIRAL 2 superconducting linac is currently under construction. This talk describes the collaboration effort with industrial partners to fabricate the two cryomodule families: the low beta Cryomodule A, and the high beta Cryomodule B. The low beta family is composed of 12 single cavity cryomodules. The high energy section is composed of 7 cryomodules hosting 2 cavities each. The design goal for the accelerating field Eacc of the SPIRAL 2 QWRs is 6.5 MV/m.
DESY, Hamburg
Fermilab, Batavia
KEK, Ibaraki
With a now extended plan to 2012, the ILC Global Design Effort Technical Design Phase focuses on key R&D to verify performance goals and to reduce both technical risk and cost. This talk will review the progress during the last two years, and plans for the future.
NSCL, East Lansing, Michigan
SLAC, Menlo Park, California
Determination of exact values of beam emittance is important for future linear collider. Beam emittance measurements technique is based on measurement of beam sizes at several beam profile stations in a quadrupole channel shifted between each other by a specific value of phase advance of betatron oscillations. Four-dimensional beam emittance measuremenst requires determination of ten values of the beam σ-matrix, while two-dimensional beam emittance measurements scheme requires determination of six values of σ-matrix. Measurement procedure is sensitive to variation of beam sizes at the beam profile stations, which might result in unstable determination of beam emittance. Paper discusses errors of beam emittance measurements as a function of errors in beam size measurement. Regions of stable and unstable beam emittance measurements are determined.
ELETTRA, Basovizza
Funding: "The work was supported in part by the Italian Ministry of University and Research under grant FIRB-RBAP045JF2 or grant FIRB-RBAP06AWK3 or grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3"
FERMI@Elettra is a FEL user facility under construction at Sincrotrone Trieste, Italy. It will use the existing normal conducting S-band Linac and seven accelerating sections received from CERN after the LIL decommissioning. Two additional new sections are also foreseen. The Linac repetition rate will be 10 Hz during the initial stage of operation, but it will be ramped up from 10 Hz to 50 Hz. Due to the higher RF power dissipation, the temperature distribution on the copper structure will reach higher values. RF heating will imply a thermal deformation of the accelerating cavities, both in the transversal and in the longitudinal direction. Since FERMI@Elettra has stringent requirements on phase stability, the length of the section must be kept as constant as possible. In this paper the thermo-mechanic behaviour of the accelerating sections is investigated and the results of the simulations are presented. Furthermore an algorithm has been developed to control the longitudinal deformation of the sections.
UCLA, Los Angeles, California
INFN/LNF, Frascati (Roma)
Rome University La Sapienza, Roma
A hybrid photoinjector, which we present here, consists of a 6-cell traveling wave structure with a standard 1.6-cell RF gun attached to the one end and a 3-m long linac following for further acceleration. With this structure, no reflection observed at the input port. This enables to build the accelerator without a circulator which limits the power and the frequency of RF. From the beam dynamics point of view, the beam is produced as the normal RF guns and gets short by velocity bunching in the traveling wave section right after the gun. The peak current can reach more than 1 kA, with about 2 mm.mrad of the emittance at 20 MeV. We discuss more details about the beam dynamics as well as the RF structure.
UCLA, Los Angeles, California
The velocity bunching is a hot topic in normal conducting photoinjectors to generate high-brightness beams instead of magnetic chicanes in the low energy region. We apply this technique to the superconducting photoinjectors. The linac considered here consists of several 9-cell TESLA cavities, the standard 1.6-cell normal conducting RF gun is assumed, though. In the case of 1.1 nC injection, the peak current increases to 1 kA with 2.6 mm.mrad of the emittance. The peak current can be higher but the emittance becomes worse in that case, and vice versa. We discuss more details on the spot.
TRIUMF, Vancouver
DAE/VECC, Calcutta
SFU, Burnaby, BC
ANL, Argonne
The TRIUMF ARIEL Project plans to build a 50MeV electron linac at 10mA to produce radioactive ion beams through photofission. Beam dynamics studies of the accelerator are on-going. The TRACK code originally written to simulate proton and heavy ion linacs has been used in e-linac modeling studies. This paper will summarize the TRACK simulation studies and the simulation results will be compared with other codes like PARMELA and ASTRA.
University of Delhi, Delhi
Fermilab, Batavia
It is well known that Insertion of a coupler into a RF cavity breaks the rotational symmetry of the cavity, resulting in an asymmetric field. This asymmetric field results in a transverse RF Kick*. This RF kick transversely offsets the bunch from the nominal axis & it depends on the longitudinal position of the particle in the bunch. Also, insertion of coupler generates short range transverse wake field** which is independent from the transverse offset of the particle. These effects cause emittance dilution and it is thus important to study their behavior & possible correction mechanisms. These coupler effects, i.e. coupler’s RF kick & coupler's wake field are implemented in a beam dynamics program, Lucretia. Calculations are done for Main Linac. For ILC like Lattices Results are compared with analytical results. and a good agreement has been found.
*N.Solyak et al, “RF Kick in the ILC Acceleration Structure. ” MOPP042.pdf (EPAC 08).
** N.Solyak et al, “Transverse Wake Field Simulation for the ILC Acceleration Structure”. MOPP043 pdf (EPAC 08).
CERN, Geneva
The specification for vacuum pressure in the CLIC electron Main Linac critically depends on the fast ion instability. In fact, the maximum tolerable pressure value in the pipe of the Main Linac is dictated by the threshold above which the fast ion instability sets in over a CLIC bunch train. Previous calculation based on ion generation from residual gas ionization alone showed that, due to the loss of the trapping along the linac caused by the beam size shrinking from acceleration, a pressure as high as 10 nTorr could be accepted, higher than the tolerable value in the long transfer line. However, since the accelerated beam becomes transversely very small, its electric field can reach values above the field ionization threshold. When this happens, the whole space region with a sufficiently high electric field gets instantly fully ionized by the first bunch and the effect on the bunch train could be severe. We have modeled field ionization in our simulation code FASTION and re-evaluated the onset of fast ion instability in the Main Linac.
CERN, Geneva
In the main linac of the compact linear collider (CLIC) , wakefield induced multi-bunch effects are important. They have a strong impact on the choice of accelerating structure design. The paper presents the limit for the wakefield that one bunch exerts on the next. It also gives estimates for the allowed level of persistent wake fields and on the resistive wall wakefield.
Fermilab, Batavia
In the paper the results are presented for calculation of the transverse wake and RF kick from the power and HOM couplers of the acceleration structure. The beam emittance dilution caused by the couplers is calculated for the main linac and bunch compressor of ILC. It is shown that for the bunch compressor this effect may constitute a problem, and modification of the coupler unit may be necessary in order to preserve the cavity axial symmetry.
KEK, Ibaraki
The International Linear Collider will employ tens of thousands of superconducting 9-cell accelerating structures for its main linacs. Damping of higher order modes is crucial to beam stability. Study of higher order modes, however, tends to focus on trapped modes in a single 9-cell structure model alone both in simulation and measurement. Propagating modes above cut-off frequencies are left untouched because of difficulty of a realistic model of multiple 9-cell structures. We have simulated a full spectrum of higher order modes in a long string of 9-cell structures.
SLAC, Menlo Park, California
Funding: Work supported by the DOE under contract DE-AC02-76SF00515.
Facilities for Accelerator Science and Experimental Test Beams (FACET) is a proposed facility at SLAC that would use the initial two-thirds of the linac to transport e+ and e- beams to an experimental region. A principal use of this facility is to identify the optimum method for accelerating positrons in a beam driven plasma wakefield accelerator. To study this, a positron bunch, followed ½ an rf cycle later by an electron bunch, will be accelerated to an asymmetric chicane designed to move the positrons behind the electrons, and then on to the plasma wakefield test stand. A major focus of study was the coupling of jitter of the positron bunch to the electron bunch via linac wakes. Lucretia is a Matlab toolbox for the simulation of electron beam transport systems, capable of multi-bunch tracking and wakefield calculations. With the exception of the lack of support for tracking of electrons and positrons within a single bunch train, it was well suited to the jitter coupling studies. This paper describes the jitter studies, including modifications made to Lucretia to correctly simulate tracking of mixed-species bunch trains through a lattice of magnetic elements and em wakes.
KEK, Ibaraki
Sokendai, Ibaraki
MELCO SC, Tsukuba
SINAP, Shanghai
The 8-GeV linac at KEK provides electrons and positrons to several accelerator facilities. A 50-Hz beam-mode switching system has been constructed to realize simultaneous top-up injections for Photon Factory and the KEKB high- and low-energy rings, which require different beam characteristics. An event-based timing and control system was built to change the parameters of various accelerator components within 20 ms. The components are spread over a 600-m linac and require changes to a total of 100 timing and control parameters. The system has been operated successfully since the autumn of 2008 and has been improved upon as beam operation experience has been accumulated. It is expected to enhance the quality of the experiments at KEKB and PF. We describe the details of this new and improved control system and present status of the accelerator operation.
LBNL, Berkeley, California
Funding: Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The high-level software for the ALS injector control system is being rewritten synchronizing with the low-level hardware migration to the EPICS system*. New programs are all written in C# for the use on the new operator consoles that are Windows Vista PCs. We use SCA. NET for the channel access, WCF for IPC, and XML for configurations. GUI is currently in WinForm but moving to WPF. We will be reporting the result of the first release of the system from the aspect of the software development.
*The progress was reported at PCaPAC 2008 as http://users.cosylab.com/~mpelko/PCaPAC08/papers/mow02.pdf,and
http://users.cosylab.com/~mpelko/PCaPAC08/papers/tup018.pdf
SLAC, Menlo Park, California
Funding: Department of Energy contract DE-ACO3-76SF00515
We describe an integrated relational database for beamline element configuration and online accelerator modelling for LCLS. It is hosted in Oracle, from which online controls software, optimization applications and feedback, use a programming interface to acquire the element data and model. Database population is by an automated process starting with a MAD deck, which is processed in Matlab to derive text files that describe the beamline elements whose data are uploaded using Oracle Loader, and the resulting Oracle APEX applications and reports are used for survey, cabling, metrology and other facilities. An automated facility for online model generation creates an XAL online model beamline description file using a database query; the resulting model is then tracked, and results can be loaded back into the database. As such, both the design or extant machine model, of the present and all previous model runs are available, and linked to the relevant element configuration. We present the process flow from the MAD design to the database, the database schema, the database applications, the process of generating a machine model, and some scientific software which uses the database.
SLAC, Menlo Park, California
Funding: Work supported in part by Department of Energy contract DE-AC02-76SF00515.
An x-ray Free-Electron Laser (FEL) calls for a high brightness electron beam. Generically, such a beam needs to be accelerated to high energy on the GeV level and compressed down to tens of microns, if not a few microns. The very bright electron beam required for the FEL has to be stable and the high quality of the electron beam has to be preserved during the acceleration and bunch compression. With a newly developed model independent global optimizer*, here we report study for the control and error diagnostics of such a generic machine: magnetic elements, and RF cavities, and the electron beam parameters: the peak current, centroid energy, and trajectory. Collective effects, such as coherent synchrotron radiation, space charge, and various wakefields are incorporated in a parametric approach. Applicability and verification are detailed for the LINAC Coherent Light Source, an x-ray FEL project being commissioned at SLAC.
*M.J. Lee, SLAC Report in press (2009).
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
The ALICE accelerator is a 35MeV energy recovery linac prototype at Daresbury in the U.K. Due to the highly experimental nature of the accelerator, there has been a strong influence of accelerator physicists in the high-level control software for the machine. Starting from the underlying EPICS-based control system, a suite of interactive commissioning software has been built using traditional software approaches, such as LabVIEW, as well as experimenting with interactive, rapid prototyping programming languages, such as Mathematica. Using the EPICS Channel Access protocols, the control system is flexible and extensible. A wide range of tools can be used to develop and debug high-level software, allowing machine physicists to use the most appropriate and familiar tools for software development.
SLAC, Menlo Park, California
Funding: Work supported by US DOE
For LCLS, an uptime of 95% of the scheduled beam time is aimed for. This is a challenging goal for a linac-driven facility, exceeding typical up time during PEP-II running by a significant amount. During the 2008 and the 2009 LCLS beam-commissioninng runs we have been gathering and analysing statistics to identify the worst offenders as far as downtime is concerned. In 2008, an overall hardware uptime of 90% was achieved, indicating the need to decrease our downtime by a factor of two. One approach to focus the effort has been to identify those faults that cause the worst performance for a system in a given time period and focus on these. Another one is to compare our MTTR performance with that of other facilities thus identifying where our processes might be improved. In this paper we will show how we track our performance and examples of the benefit of addressing identified reliability issues.
ORNL, Oak Ridge, Tennessee
RAS/INR, Moscow
Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
SNS is a high intensity hadron beam facility; so the Beam Loss Monitor (BLM) system is a crucial part of Machine Protection System and an important tool for beam tuning. The paper presents the current status of installed detectors and experimental data obtained during SNS operations. We compare several different types of BLMs and show advantages and disadvantages of each type. The electronic parts obsolescence became a real issue since the original electronics was designed about 10 years ago. The first test of our next generation BLM system is expected to be done by summer 2009. The new system will contribute to significant noise reduction and will follow a modular concept of Smart Device to achieve a higher degree of reliability and maintainability.
SLAC, Menlo Park, California
Funding: SLAC/DOE Contract DE-AC02-76-SF00515
A state-of-the-art Machine Protection System for the SLAC Linac Coherent Light Source has been designed and built to shut off the beam within one pulse during 120 Hz operation to protect the facility from damage due to beam losses. Inputs from beam loss monitors, BPMs, toroids and position switches of insertable beam line devices are connected to a number of Link Node chassis placed along the beam line. Link Nodes are connected with a central Link Processor in a star topology on a dedicated gigabit Ethernet fiber network. The Link Processor, a Motorola MVME 6100, processes fault data at 360 Hz. After processing, rate limit commands are sent to mitigation devices at the injector and just upstream of the entrance of the sensitive undulator beam line. The beam's repetition rate is lowered according to the fault severity. The SLAC designed Link Nodes support up to 96 digital inputs and 8 digital outputs each. Analog signals are handled via standard IndustryPack (IP) cards placed on the Link Node motherboards with optional transition boards for signal conditioning. A database driven algorithm running on the Link Processor provides runtime loadable and swappable machine protection logic.
ANL, Argonne
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
An energy upgrade project of the ATLAS heavy ion linac at ANL includes a new cryomodule containing seven {10}9 MHz β=0.15 quarter-wave superconducting cavities to provide an additional 15 MV voltage to the existing linac. Several new features have been incorporated into both the cavity and cryomodule design. For example, the primary feature of the cryomodule is a separation of the cavity vacuum space from the insulating vacuum. The cavities are designed in order to cancel the beam steering effect due to the RF field. The cryomodule was designed and built as a prototype for the driver linac of the Facility for Rare Isotope Beams (FRIB). Similar design can be effectively used in the SC proton linac for the Project X at FNAL. Currently, we are working on cryomodule assembly and final preparation of cryogenics, RF, vacuum and other subsystems for off-line tests. The initial commissioning results will be reported.
BNL, Upton, Long Island, New York
Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka
IAP, Frankfurt am Main
Department of Energy Sciences, Tokyo Institute of Technology, Yokohama
Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A new 4 rod RFQ fabricated by IAP, Frankfurt, is being commissioned at Brookhaven National Laboratory. The RFQ will accelerate intense heavy ion beams provided by an Electron Beam Ion Source (EBIS) up to 300 keV/u. The RFQ will accelerate a range of Q/M from 1 to 1/6, and the accelerated beam will be finally delivered to RHIC and NSRL. The first beam test is planned to use beams from the BNL Test EBIS. The detailed test results will be presented.
BNL, Upton, Long Island, New York
In this paper we report the current status of the studies of a phenomenon of microbunching at NSLS Source Development Laboratory (SDL). We observed the microbunching inside 70MeV electron bunches even for subpicosecond beams of 10pC charge. Additional microbunching is formed when the beam is compressed in the bunch compressor utilizing the 4-magnet chicane. We study the mechanisms of microbunching in an electron beam generated by a 100fs laser pulse. It allows reducing the possibility of having beam structures induced by photo-injector laser, eliminating effects of RF curvature, and enhancing the longitudinal space charge (LSC) and the coherent synchrotron radiation (CSR) effects.
BNL, Upton, Long Island, New York
At BNL NSLS Source Development Laboratory (SDL) 70MeV electron bunches are compressed by the bunch compressor (BC) consisting of a linac section followed by a 4-magnet chicane. The achievable beam compression is limited by nonlinear beam dynamics in the BC and by coherent synchrotron radiation (CSR) effect. In this report we present a novel beam-based technique of chicane calibration, describe the measurements of CSR effect on the beam in the chicane, and discuss the possible scenarios of the BC optimization.
CERN, Geneva
The PIMS will accelerate an H- beam from 100 MeV to 160 MeV, the output energy of Linac4. The cell length is constant within each of the 12 seven-cell cavities, but increases from cavity to cavity according to the increasing beam velocity. Its mechanical design is derived from the five-cell normal conducting LEP cavities, which were in operation at CERN for approximately 15 years. Even though the shunt impedance is around 10% lower than for a Side-Coupled Linac (SCL) operating at 704 MHz, the PIMS has the advantage of using the same RF frequency (352 MHz) as all the other accelerating structures in Linac4, thus simplifying and standardising the linac RF system. Furthermore, the simplified mechanical construction of the PIMS, which uses only 84 cells instead of over 400 for the SCL, also reduces construction costs and tuning effort. In this paper we present the electromagnetic design of the PIMS, including the arguments for the choice of a 5% cell-to-cell coupling factor, the shape of the coupling cells, the dimensioning of the wave-guide ports, and the expected field errors during operation.
CERN, Geneva
The civil engineering works of the Linac4 linear accelerator at CERN started in October 2008 and regular machine operation is foreseen for 2013. Linac4 will accelerate H- ions to an energy of 160 MeV for injection into the PS Booster (PSB). It will thus replace the ageing Linac2, which presently injects at 50 MeV into the PSB, and it will also represents the first step in the injector upgrade for the LHC aiming at increasing its luminosity. This paper reports on the status of the design and construction of the main machine elements, which will be installed in the linac tunnel from the beginning of 2012 onwards, on the progress of the civil engineering and on the ongoing activities at the Linac4 test stand.
CERN, Geneva
KIP, Heidelberg
In this paper is analysed the influence of Higher Order Modes (HOM) on the operation of the superconducting linac section of the SPL, the Superconducting Proton Linac being designed at CERN. For this purpose, the characteristics of the HOMs in the 2 different beta families (0.65, 0.92 both at 704 MHz) of the SPL are calculated to estimate their effect on the cryogenic system and on the beam stability. For both criteria the maximum external Q of the HOMs is defined.
CERN, Geneva
A one meter long hot prototype of the LINAC4 DTL, built in a collaboration with INFN Legnaro, was delivered to CERN in 2008. It was then copper plated at CERN is and is presently prepared for high-power testing at the CERN test stand in SM18. In this paper we present 2D/3D simulations and the first RF low-power measurements to verify the electromagnetic properties of the cavity and to tune it before the high-power RF tests. In particular, the influence of the post couplers was studied in order to guarantee stabilization of the accelerating field during operation. We present an equivalent circuit model of the DTL, together with a comparison of 3D simulations and measurement results for the hot model.
CERN, Geneva
Construction work for the new CERN linear accelerator, Linac4, started in October 2008. Linac4 will replace the existing Linac2 and provide an H- beam at 160 MeV (as opposed to the present 50 MeV proton beam) for injection into the CERN PS Booster (PSB). The charge-exchange H- injection combined with the higher beam energy will allow for an increase in beam brightness required for reaching the ultimate LHC luminosity. Commissioning of Linac4 and of the transfer line to the PSB is planned for the last quarter of 2012. Appropriate beam instrumentation is foreseen to provide transverse and longitudinal beam characterization at the exit of Linac4 and in two dedicated measurement lines located before injection into the PSB. A detailed description of the diagnostics set, especially of spectrometer and emittance meter, and the upgrade of the measurement lines for Linac4 commissioning and operation is presented.
Fermilab, Batavia
NSCL, East Lansing, Michigan
ANL, Argonne
A superconducting cavity has been designed for acceleration of particles traveling at 81% the speed of light (beta = 0.81). The application of interest is an 8 GeV proton linac proposed for a Fermilab upgrade; at present, the cavity is to be used from 420 MeV to 1.3 GeV. The cavity is similar to the 805 MHz high-beta cavity developed for the SNS Linac, but the resonant frequency (1.3 GHz) and beam tube diameter (78 mm) are the same as for the beta = 1 cavities developed for the TESLA Test Facility. Four single-cell prototype cavities have been fabricated and tested. Two multi-cell prototypes have also been fabricated, but they have not yet been tested. The original concept was for an 8-cell cavity, but the final design and prototyping was done for 7 cells. An 11-cell cavity was proposed recently to allow the cryomodules for the beta = 0.81 cavity and downstream 9-cell beta = 1 cavities to be identical. The choice of number of cells per cavity affects the linac design in several ways. The impact of the number of cells in the 8 GeV linac design will be explored in this paper. Beam dynamics simulations from the ANL code TRACK will be presented.
Fermilab, Batavia
Funding: Work performed by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The High Intensity Neutrino Source (HINS) linac R&D program at Fermilab is constructing a first-of-a-kind superconducting H- linac. The machine will demonstrate acceleration of high intensity beam using superconducting spoke cavities, solenoidal focusing optics throughout for control of halo growth, and operation of many cavities from a single high power rf source for acceleration of non-relativistic particles. The ion source and RFQ are operational with beam and the 10 MeV room temperature cavity section is being assembled. Superconducting spoke cavity testing is proceeding. The overall status and outlook of the HINS program is presented.
GSI, Darmstadt
The GSI UNILAC serving as a high duty factor heavy ion linac is in operation since nearly 35 years. An upgrade program dedicated to FAIR will be finished until 2011. For the FAIR project the synchrotron SIS 18 has to be filled up to the space charge limit. After re-commissioning of the UNILAC the replacement of the main DTL is foreseen. A new 4 MV/m 108 MHz IH-LINAC provides a high intensity 5 MeV/u U4+-beam. The existing gas stripper section is reused to perform a beam intensity of 24 emA in charge state 42+. The existing UNLAC-tunnel may house a high efficient linac structure. A superconducting or normal conducting 324 MHz-CH-linac (crossbar H-structure) is under consideration as well as rf-resonators of half wave or quarter wave type. The new high energy linac should be able to boost the beam energy up to 30 MeV/u. A further upgrade option is a second 100 m-linac (324 MHz) to enhance the beam energy to up to 100 MeV/u (U41+), sufficient to feed the FAIR 100 Tm synchrotron in direct line. The paper will report on the ongoing conceptual layout of a new UNILAC-concept.
IAP, Frankfurt am Main
GSI, Darmstadt
For the research program with cooled antiprotons at FAIR a dedicated 70MeV, 70mA proton injector is needed. The main acceleration of this room temperature injector will be provided by six coupled CH-cavities operated at 325MHz. Each cavity will be powered by a 3 MW klystron (6 in total). For the second acceleration unit from 11.7 to 24.3 MeV measurements on a 1:2 scaled model are performed. This tank is now ready for construction and will be used for RF power tests at GSI. The RF power test installations are underway. This paper presents the CH-DTL design and especially the status of the first power cavity.
IAP, Frankfurt am Main
The superconducting CH-cavity is the first multi-cell drift tube cavity for the low and medium energy range of proton and ion linacs. A 19 cell, beta=0.1 cavity has been developed and tested successfully with gradients of up to 7 MV/m. A piezo based fast tuner system has been developped. First horizontal tests of the cavity in a cryo-module with tuner are presented. Additionally, the construction of a new superconducting 325 MHz 7-gap CH-cavity has started. This cavity has an optimized geometry with respect to tuning possibilities, high power RF coupling and minimized end cell lengths. After low power tests it is planned to test this cavity with a 11.4 MeV/u beam delivered by the Unilac at GSI.
IAP, Frankfurt am Main
Funneling is a method to increase low energy beam currents in multiple stages. The Frankfurt Funneling Experiment is a model of such a stage. The experiment is built up of two ion sources with a electrostatic lens systems, a Two-Beam RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ and the last parts of the RFQ electrodes achieve a 3d focus at the crossing point of the two beam axis. A funneling deflector combines the bunches to a common beam axis. The optimized ion sources are adapted to the front end bunching section. Recent funneling measurements with the one-gap and the multi-gap deflector will be presented.
IUCF, Bloomington, Indiana
LANL, Los Alamos, New Mexico
Funding: LENS is supported by the National Science Foundation grants DMR-0220560 and DMR-0320627, the 21st Century Science and Technology fund of Indiana, Indiana University, and the Department of Defense.
The Indiana University Cyclotron Facility is operating a Low Energy Neutron Source which provides cold neutrons for material research and neutron physics as well as neutrons in the MeV energy range for neutron radiation effects studies. Neutrons are being produced by a 13 MeV proton beam incident on a Beryllium target. The LENS Proton Delivery System (PDS) is routinely operating at 13 MeV and 25 mA at 1.8% duty factor. The RF system, consisting of three Litton 5773 klystron RF tubes at 425 MHz and 1 MW each, power the AccSys Technology PL-13 Linac. The proton beam delivers 6 kilowatts of power to the Beryllium target. Details of the beam spreading system, target cooling system, and accelerator operations will be discussed.
KAERI, Daejon
Funding: This work is supported by MEST of the Korean Government
A 100 MeV DTL as a main accelerating section of the PEFP proton linac is under development. The PEFP proton linac consists of a 50 keV proton injector based on a duoplasmatron ion source, 3 MeV four-vane RFQ, 20 MeV DTL and 100 MeV DTL. The 100 MeV DTL is composed of 7 tanks and each tank is an assembly of 3 sections. The tank is made of seamless carbon steel and inside surface is electroplated with copper. Each drift tube contains an electroquadrupole magnet which is made of hollow conductor and iron yoke with epoxy molding. Following the fabrication of tanks and drift tubes, a precise alignment of drift tubes and field flatness tuning procedure are performed. Currently four DTL tanks out of seven are completed and the rest are under fabrication. The status of development and test results of the fabricated parts are reported in this paper.
LANL, Los Alamos, New Mexico
Muon accelerators are proposed world wide for future neutrino factory, muon colliders and other applications. One of the problem on accelerating muons is their large emittance as well as huge energy spreads. We carried out some simulation works on large acceptance muon linear accelerator that operates at mixed buncher / acceleration mode. The designed linac has following features: iris structure of 12 cm diameter, inject ~100 MeV muon beam and accelerates to several 100 MeV, 700 MHz and 25 MV/m peak field. Further acceleration of the muon beam can be easily done by extending the muon linear accelerator. According to the simulation, our linac can accelerates DC muon beam of 20 - 100 MeV range with 20 % phase acceptance.
LANL, Los Alamos, New Mexico
Funding: This work is supported by the U. S. Department of Energy, Contract DE-AC52-06NA25396.
The Los Alamos Neutron Science Center simultaneously provides both H- and H+ beams to several user facilities. Opposite polarity beams are usually accelerated in the linac during the same macropulse when beam-loading limitations are not exceeded. Presently, the Weapons Neutron Research (WNR) H- and Isotope Production Facility (IPF) H+ beams are accelerated simultaneously during the same macropulse. The amplitude of the cavity field in the last 201-MHz buncher, located in the common transport just upstream of the DTL, is a compromise between the optimal values for each beam. Recent beam dynamics studies have shown that implementing a debuncher cavity in the H- low-energy beam transport would allow for more optimal operation of both beams. For this application where space is limited, a compact 201-MHz quarter-wave cavity will be used. This paper will report on the beam dynamics simulations performed and the quarter-wave cavity design being developed to address this issue.
NSCL, East Lansing, Michigan
Funding: This work is supported by the U.S. Department of Energy
The superconducting (SC) driver linac developed for the proposed Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) will be able to accelerate stable beams of heavy ions to > 200 MeV/u with beam powers up to 400 kW. The driver linac front-end will include ECR ion sources, a bunching system for multi-charge state beams and a radio frequency quadrupole (RFQ). The superconducting linac will have a base frequency of 80.5 MHz primarily using SC cavities and cryomodules developed for the Rare Isotope Accelerator (RIA), the FRIB predecessor. A charge-stripping chicane and multiple-charge state acceleration will be used for the heavier ions in the driver linac. A beam delivery system will transport beam to the in-flight particle fragmentation target station. The paper will discuss recent progress in the accelerator system design for the superconducting driver linac.
Istituto Nazionale di Fisica Nucleare, Milano
Universita' degli Studi di Milano & INFN, Segrate
Naples University Federico II and INFN, Napoli
CERN, Geneva
Bari University, Science Faculty, Bari
e2v, Chelmsford, Essex
INFN-Bari, Bari
ACLIP is a proton 3 GHz SCL linac designed as a booster for a 30 MeV commercial cyclotron . The final energy is 60 MeV well suitable for the therapy of ocular tumours or for further acceleration (up to 230 MeV) by a second linac in order to treat deep seated tumours. ACLIP has a 5 modules structure coupled together. The first one (able to accelerate proton from 30 to 35 MeV) has been completely assembled. High power tests are in progress at e2v in Chelmsford, UK, where the possibility of using magnetrons as the source of RF power is under investigation. Acceleration tests are foreseen for Spring 2009. In this paper we will review the main features of the linac and discuss the results of RF measurements, high power RF tests and possibly acceleration tests.
Naples University Federico II and INFN, Napoli
Istituto Nazionale di Fisica Nucleare, Milano
Naples University Federico II, Napoli
The use of BBAC (Back-to-Back Accelerating Cavity) tiles in proton Side Coupled Linacs can be extended down to energies of the order of 20 MeV, keeping more than suitable shunt impedances and energy gradients. However, the considerable energy absorption from the cavity noses may induce a remarkable increase in their temperature. This may cause both a strong duty-cycle-dependent detuning of the modules, and dangerous thermo-mechanical stress due to the non-uniform temperature distribution. An innovative shape of the BBAC tile is proposed, which allows to limit the temperature rise within a safe range, without introducing detrimental effects neither on the shunt impedance nor on the working frequency. A protocol for the design of such a cavity will be presented.
NSRRC, Hsinchu
Operation performance of the linear accelerator is crucial to satisfy stringent requirements for the top-up operation of the Taiwan Light Source. The performance of linear accelerator affects injector stability directly. Efforts to improve diagnostics and develop control applications for performance characterization are on going. Enhance operation performance of 50 MeV linac is also under way. Efforts for the improvement of the linac to provide better top-up injection performance will be summary in this report.
ORNL, Oak Ridge, Tennessee
GSI, Darmstadt
The 4ν=1 resonance of a linac is demonstrated when the depressed tune is around 90 deg. It is observed that this fourth order resonance is dominating over the better known envelope instability and practically replacing it. Simulation study shows a clear emittance growth by this resonance and its stopband. One of the authors [DJ] made a proposal to GSI to measure the stopband of this resonance. The experiment was conducted successfully and the experiment data will be presented separately in the conference.
PKU/IHIP, Beijing
Funding: supported by NSFC (19775009)
A trapezoidal IH-RFQ (T-IH-RFQ) is being built to accelerate 14C^+ from 40 keV to 500 keV, motivated by RFQ based 14C AMS application at Peking University. The last design of beam dynamics and the optimized results of RF structure will be presented in this paper. The length of the cavity is about 1.1m operating at {10}4MHz, with a designed transmission efficiency of more than 97%. A special feature is that the RFQ output beam energy spread is as low as 0.6% approached by the method of internal discrete bunching. On the other hand, the new RF cavity structure T-IH-RFQ was proposed for the beam dynamics design, which has higher resonant frequency than traditional four rods RFQ and IH-RFQ at the same transverse dimension. Microwave Studio (MWS) simulations have been performed to study the field distribution and power consumption characteristic of this T-IH-RFQ. The specific shunt impedance and the quality factor have been optimized. Those details will be given.
POSTECH, Pohang, Kyungbuk
PAL, Pohang, Kyungbuk
NFRI, Daejon
Funding: This work is supported by KAPRA and POSTECH Physics BK21 Program.
An intense L-band electron linac is now being commissioned at ACEP (Advanced Center for Electron-beam Processing in Cheorwon, Korea) for irradiation applications. It is capable of producing 10-MeV electron beams with the 30-kW average beam power. For a high-power capability, we adopted the traveling-wave structure operated with the 2π/3-mode at 1.3 GHz. The structure is powered by a 25-MW pulsed klystron with 60-kW average RF power. The RF pulse length is 8 μs while the beam pulse length is 7 μs due to the filling time in the accelerating structure. The accelerating gradient is 4.2 MV/m at the beam current of 1.45 A which is the fully beam-loaded condition. In this paper, we present details of the accelerator system and commissioning status.
RLNR, Tokyo
An Interdigital-H (IH) linac has been used for ion acceleration in low beta range. It can realize a resonant cavity of a convenient size at low frequencies and higher shunt impedance at low energy range. These characteristics are advantageous especially for heavy ion acceleration. Since the shunt impedance of the IH linac reduces according to the increasing of beam energy, the linacs operated by the TM010 mode such as an Alvarez type and a coupling cavity type are adopted for medium and high energy range. However, we propose the new IH linac using the TE11n mode, the higher order mode IH (HOM-IH) linac. By using the higher order mode, the resonance frequency is higher than that of the IH linac. This property is suitable for middle and high beta linacs, and a proton linac as well. The design of the cavity structure and the possibility are presented.
SAMEER, Mumbai
The developmental work on linear electron accelerators in SAMEER, India is briefed in this paper. The technology to develop ‘S’ band compact side coupled standing wave electron linear accelerator is very well established at SAMEER, Mumbai center. 6 MV to 15 MV linacs are developed with the desired specifications. Indigenous 6 MV linac machines for radiotherapy applications have been developed successfully and these machines are in use at premier cancer hospitals in the country. SAMEER is presently working on the development of the dual mode-electron and photon and dual photon energy linear accelerator for radiotherapy application. The 6 MeV linac tube development and its test results are discussed.
USP/LAL, Sao Paulo
Funding: FAPESP, CNPq
The Instituto de Física da Universidade de São Paulo (IFUSP) is building a two-stage 38 MeV continuous wave racetrack microtron. This accelerator consists of a linac injector that delivers a 1.7 MeV beam to a microtron (booster) with 5 MeV exit energy. A transport line guides the beam to the main microtron to be accelerated to energies up to 38 MeV in steps of 0.9 MeV. This work describes the commissioning of the linac injector that comprises the first two accelerating structures of the IFUSP Microtron. A provisional beam line was built at the end of the linac to provide energy and current measurements. We also present results concerning RF power, RF phase, and temperature control of the accelerating structures. The first results of the chopper and buncher systems are also presented.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Future projects like a neutrino factory or an advanced spallation neutron source require high power proton accelerators capable of producing beams in the multi-MW range. The quality of the beam delivered to the target is very much dictated by the accelerator front end and by the lower energy linac. Prompted by the Front End Test Stand (FETS) under construction at Rutherford Appleton Laboratory (RAL), a new 800 MeV H- linac is being considered as part of a possible MW upgrade for ISIS. Preliminary simulations of high intensity beam dynamics and beam transport in the new linac suggest that a re-evaluation of the front end Medium Energy Beam Transport (MEBT) line is necessary. In this paper different optical designs for the 3 MeV MEBT line are presented and their impact on the subsequent Drift Tube Linac (DTL) section is being analysed.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Features of a linac and ring for potential ISIS upgrades are outlined. Maximum parameters are 0.8 GeV, 0.5 MW for the H(-)linac and 3.2 GeV, 2 MW for the ring, both at 30 or 50 Hz. The linac is based on a 324 MHz frequency at low energies, having an ion source, LEBT, 3 MeV RFQ and MEBT, with A 74.8 MeV drift tube linac (DTL) and intermediate energy beam transport (IEBT). The MEBT chopper stage uses solenoid and triplet focusing, and both MEBT and IEBT have long sections for beam collimation. There are three options for the higher energies, a 648 MHz superconducting linac(ScL1, ScL2 and ScL3), a 648 MHz (CCL, ScL2 and ScL3), and a 324 MHz (ScLa) with a two-stage 972 MHz (ScLb and ScLc). The ScL1, CCL and ScLa are designed to accelerate the H(-) beam from 74.8 to ~200 MeV. The proton synchrotron design is based on a five superperiod lattice of doublet and triplet cells, and has a circumference of ~ 370 m.
Soreq NRC, Yavne
ACCEL, Bergisch Gladbach
The Soreq Applied Research Accelerator Facility, SARAF, is currently under construction at Soreq NRC. SARAF is based on a continuous wave (CW), proton/deuteron RF superconducting linear accelerator with variable energy (540 MeV) and current (0.04-2 mA). SARAF is designed to enable hands-on maintenance, which implies beam loss below 10-5 for the entire accelerator. Phase I of SARAF consists of a 20 keV/u ECR ion source, a low energy beam transport section, a 4-rod RFQ, a medium energy (1.5 MeV/u) transport section, a superconducting module housing 6 half-wave resonators and 3 superconducting solenoids, a diagnostic plate and a beam dump. Phase II will include 5 additional superconducting modules. The ECR source is in routine operation since 2006, the RFQ is in routine operation with protons since 2008 and has been further operated with molecular hydrogen and deuterons. The superconducting module is being operated and characterized with protons. Phase I commissioning results, their comparison to beam dynamics simulations and Phase II plans will be presented.
THALES, Colombes
CELLS-ALBA Synchrotron, Cerdanyola del Vallès
EuroMev, Buc
A turn key 100 MeV linac was provided by THALES Communications in order to inject electrons into the booster synchrotron of ALBA*. The linac was commissioned in October 2008. This paper will remind the main features of the linac** and will give results obtained during the commissioning tests. The energy and emittance measurements have been done on the transfer line concieved and realized by CELLS. Specified and measured beam parameters will be compared to show the performance of the entire system.
* D. Einfeld "Progress of ALBA", EPAC08, Genoa, Italy, June 2008.
** A. Falone et Alt, "Status of the 100 MeV preinjector for the ALBA synchrotron", EPAC08, Genoa, Italy, June 2008.
TUB, Beijing
Funding: Work supported by National Science Foundation of China (No. 10775079)
On the basis of an X-band 2MeV on-axis standing wave electron linear accelerator, a compact 4MeV/2.5MeV X-band accelerator is being developed at Tsinghua University for non-destructive testing. The single tube can deliver two kinds of x-rays, with dose rate of >100cGy/min@m at 4MeV or >50cGy/min@m at 2.5MeV. To suppress the nearby modes, the coupler is set in the middle of the long coupled cavity chain. The coupled circuit model is applied to analyze the RF characteristic and the dynamic is investigated by CAV code. The prototype has being machined and tuned at our laboratory.
jfhua@mail.tsinghua.edu.cn
ENEA C.R. Frascati, Frascati (Roma)
SPARKLE S.r.l., Casarano (Lecce)
SPARKLE company is setting up in the south of Italy (Casarano) a new cyclotron facility based on a 18 MeV, 150 uA IBA Cyclone 18/9. The aim is to create a multidisciplinary research site for the medical applications of accelerators. The main activity will be the production of standard and new radionuclides, by internal targets and one external beam line. Another opposite beam line has been reserved for low current proton irradiations for radiotherapy studies, and a linac booster between 18 and 24 MeV was designed and built to this end. The beam line, which focuses and matches the beam to the linac, includes a chopping system to synchronize the beam to the pulsed linac and to collect 99% of the beam not synchronous to the linac. The linac uses a 3 GHz SCDTL structure powered by a magnetron modulator system. In the paper we report an overview of the beam line, component design, and tests.
DAE/VECC, Calcutta
UGC DAE CSR, Kolkata
An ISOL post-accelerator type of Rare Ion Beam (RIB) facility is being developed at our centre. The facility will use light ion beams from the K=130 cyclotron for producing RIBs using suitable thick targets. Also, development of an electron LINAC has been initiated with an eye to produce RIBs using the photo-fission route. The RIBs will be ionized, mass separated and the RIB of interest will be accelerated using a four rod Radio Frequency Quadrupole from 1.7 to 98 keV/u. The posts, vanes and base plate of the RFQ have been machined from OFC copper and the cavity is made from steel with its inner surface plated with copper. Oxygen beam of charge state 5+ has already been accelerated with an efficiency of around 90% through the RFQ. The first IH LINAC will accelerate RIBs up to about 186 keV/u. The octagonal shape LINAC cavity is made from explosively bonded copper cladded steel. Low power tests of the LINAC is encouraging - the beam test is scheduled for January 2009 and the results of which will be reported. The R&D efforts in various areas of this project will be discussed in this paper. Special emphasis will be given to the development of the RFQ and LINAC.
TU Darmstadt, Darmstadt
CERN, Geneva
The REX-ISOLDE radioactive ion beam facility at CERN makes great demands also on the experimentalists due to its specific duty cycle and the time structure with short beam pulses and large intensities. This paper describes the experimentalist's point of view, how to obtain sufficient and correct statistics under the special circumstances arising from the beam time structure. In particular, the case of Coulomb excitation experiments, where a large total cross section is ultimately desired, is studied in greater detail.
TRIUMF, Vancouver
The ISAC facility, located at TRIUMF, first began delivering radioactive ion beams (RIBs) in 1998, added post-accelerated beam capability in 2001, and is regarded as one of the premiere RIB facilities in the world. The existing constraints on RIBs of Z<83 and accelerated beams of A/q<30 with energies limited to 5MeV/u are being addressed. A charge-state booster for RIBs has been commissioned to alleviate the A/q<30 restriction and has successfully delivered multi-charge beams through the ISAC accelerators. The 5MeV/u license limit will be removed once an on-line beam monitor is commissioned, allowing beams of up to 11MeV/u to be delivered presently, and increased to over 20MeV/u when the next accelerator phase is installed. In 2008, an actinide target was used to produce RIBs of Z>82; this successful test was performed on a uranium target with yields measured and radiation safety monitored. A new Beam Delivery group has been formed to integrate all aspects of RIB production, which has led to improved efficiency and greater experimental results. These new capabilities will be presented, showing how 2009 promises to be both an exciting and productive year at ISAC.