KEK, Ibaraki
The general status of the International Linear Collider (ILC) project will be presented. After the publication of the RDR (Reference Design Report) in summer in 2007, the next milestone of the ILC project will be the Technical Design Report to be completed by the end of 2012. The GDE (Global Design Effort) has defined the period till 2010 summer as the Technical Design Phase 1 and is revisiting the design in RDR in the name of 'rebaselining'. The outline of the new design will be decided in March 2010 and will be reported in this talk together with the near future plan.
INFN/LNF, Frascati (Roma)
CEA, Gif-sur-Yvette
LAL, Orsay
SLAC, Menlo Park, California
The ultra high luminosity B-factory (SuperB) project of INFN requires a high performance and reliable injection system, providing electrons at 4 GeV and positrons at 7 GeV, to fulfill the very tight requirements of the collider. Due to the short beam lifetime, continuous injection of electrons and positrons in both HER and LER rings is necessary to keep the average luminosity at a high level. Polarized electrons are required for experiments and must be delivered by the injection system, due to the beam lifetime shorter than the polarization build-up: they will be produced by means of a SLAC-SLC polarized gun. One or two 1 GeV damping rings are used to reduce e+ and e- emittances. Two schemes for positron production are under study, one with electron-positron conversion at low energy (<1 Gev), the second at 6 GeV with a recirculation line to bring the positrons back to the damping ring. Acceleration through the Linac is provided by a S-band RF system made of traveling wave, room temperature accelerating structures. An option to use the C-band technology is also presented.
KEK, Ibaraki
SLAC, Menlo Park, California
CERN, Geneva
A CERN-SLAC-KEK collaboration on high gradient X-band accelerator structure development for CLIC has been ongoing for three years. The major outcome has been the demonstration of stable 100 MV/m gradient operation of a number of CLIC prototype structures. These structures were fabricated basically using the technology developed from 1994 to 2004 for the GLC/NLC linear collider initiative. One goal has been to refine the essential parameters and fabrication procedures needed to realize such high gradient routinely. Another goal has been to develop structures with stronger dipole mode damping than those for GLC/NLC. The latter requires that surface temperature rise during the pulses be higher, which may increase the breakdown rate. Structures with heavy damping will be tested in late 2009/early 2010, and this paper will present these results together with some of the earlier results from non-damped structures and structures built with a quadrant geometry.
KEK, Ibaraki
In order to improve the capture efficiency of the positron produced at the target in present KEKB Injector linac, a new project has just started to utilize L-band (1298MHz) RF. The present S-band (2856MHz) capture cavities and successive three RF units are to be replaced by those of L-band. The specifications of the L-Band system should fulfill the demands of a positron damping ring downstream which is also to be under study for super KEKB project. Besides the whole design work of the system, our present ongoing work is rather concentrated on establishing L-Band RF source and accelerating structures.
LLNL, Livermore, California
SLAC, Menlo Park, California
In support of Compton scattering gamma-ray source efforts at LLNL, a multi-bunch test stand is being developed to investigate accelerator optimization for future upgrades. This test stand will enable work to explore the science and technology paths required to boost the current 10 Hz mono-energetic gamma-ray (MEGa-Ray) technology to an effective repetition rate exceeding 1 kHz, potentially increasing the average gamma-ray brightness by two orders of magnitude. Multiple bunches must be of exceedingly high quality to produce narrow-bandwidth gamma-rays. Modeling efforts will be presented, along with plans for a multi-bunch test stand at LLNL. The test stand will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. The photoinjector will be a high gradient standing wave structure, featuring a dual feed racetrack coupler. The accelerator will increase the electron energy so that the emittance can be measured using quadrupole scanning techniques. Multi-bunch diagnostics will be developed so that the beam quality can be measured and compared with theory. Design will be presented with modeling simulations, and layout plans.
DESY, Hamburg
JLAB, Newport News, Virginia
This paper reports about our efforts to develop a flangeable coaxial coupler for both HOM and fundamental coupling for 9-cell TESLA/ILC-type cavities. The cavities were designed in early 90‘s for pulsed operation with a low duty factor, less than 1 %. The proposed design of the coupler has been done in a way, that the magnetic flux B at the flange connection is minimized and only a field of <5 mT would be present at the accelerating field Eacc of ~ 36 MV/m (B =150 mT in the cavity). Even though we achieved reasonably high Q-values at low field, the cavity/coupler combination was limited in the cw mode to only ~ 7 MV/m, where a thermally initiated degradation occurred. We have improved the cooling conditions by initially drilling radial channels every 30 degrees, then every 15 degrees into the shorting plate. The modified prototype performed well up to 9 MV/m in cw mode. This paper reports about our experiences with the further modified coaxial coupler and about test results in cw and low duty cycle pulsed mode, similar to the TESLA/ILC operation conditions.
DESY, Hamburg
High frequency Higher Order Modes (HOM) propagating in the beam line of a superconducting linac can carry a substantial fraction of the energy deposited in accelerating structures by the beam. In this contribution, we report test results of the beam line absorber (BLA), which was designed and fabricated at DESY, and installed in the FLASH accelerator to absorb the HOM energy generated by high current beams. Two tests were carried out, in September 2008 and September 2009, during so called high current runs. The experiments confirmed the concept of the BLA design and showed remarkable agreement with computer modeling of the HOM energy absorption.
TRIUMF, Vancouver
DAE/VECC, Calcutta
In July 2009 TRIUMF, in collaboration with the University of Victoria and other partners, was awarded Canadian federal government funds for the construction of an electron linear accelerator (e-linac) in support of its expanding rare isotope beam (RIB) program. The project anticipates Provincial funds for the construction of buildings to be announced in June 2010. TRIUMF has embarked on the detailed design for the 10 MeV Injector cryomodule and the first of two 20 MeV Accelerator cryomodules (ACMs), all rated up to 10 mA. The project first stage, ICM and ACM1, providing 25 MeV 4 mA is planned to be completed in November 2013. The injector is being fast tracked in a collaboration with the VECC in Kolkata, India. This paper gives an overview of the facility layout, and accelerator design progress including beam dynamics and cryomodule concept.
Siemens AG, Healthcare Technology and Concepts, Erlangen
The concept of a compact particle accelerator capable of delivering accelerating fields upto 100MV/m using a direct drive RF LINAC is explored. Such a machine consists of a succession of RF cavities with the RF power being supplied from a ring of solid state RF transistors placed around the cavity circumference. To achieve the required accelerating fields 3 core technologies are presented. (i) The solid-state transistors are used to drive the wall currents in the cavities so achieving a direct drive of the cavity. This allows unprecedented powers to be reached (>GW class) as well as enabling independent phase control of the individual cavities. Central to the implementation is the design of the RF drive consisting of distributed SiC vJFET modules delivering 750kA at 800V per cavity. (ii) A High Gradient Insulator structure is required to hold an electric field of >100MV/m. In contrast to a conventional HGI, the concept utilizes a vacuum insulated grading layer structure. (iii) A chopper and injection system allow the formation of proton bunches with a spatial emissivity <3ns and an injection field of up to 100MV/m.
DESY, Hamburg
Fermilab, Batavia
Uni HH, Hamburg
Ultra short bunches with high peak current are required for efficient creation of high brilliance coherent light at the free electron laser FLASH. They are obtained by a two stage transverse magnetic chicane bunch compression scheme based on acceleration of the beam off the rf field crest. The deviation of the rf field's sine shape from a straight line leads to long bunch tails and reduces the peak current. This effect will be eliminated by adding the Fermilab-built third harmonic superconducting accelerating module operating at 3.9 GHz to linearize the rf field. The third harmonic module also allows for the creation of uniform intensity bunches of adjustable length that is needed for seeded operation. This paper summarizes the results from the first complete rf system test at the crymodule test bench at DESY and the first experience gained operating the system with beam in FLASH.
KEK, Ibaraki
SuperKEKB, the upgrade plan of KEKB, aims to boost the luminosity up to 8·1035 /cm2/s. The beam energy of the Low Energy Ring (LER) is 4 GeV for positrons, and that of the High Energy Ring is 7 GeV for electrons. SuperKEKB is designed to produce low emittance beams. The horizontal and vertical emittances of the injection beams are 4nm and 1nm, respectively, which are one or two orders smaller than those of KEKB. The positron injector system consists of the source, capture system, L-band and S-band linacs, collimators, an energy compression system (ECS), a 1-GeV damping ring, a bunch compression system (BCS), S-band and C-band linacs, and a beam transport line into the LER. This paper reports a design of the positron beam transport system from L-band linacs to SuperKEKB.
KEK, Ibaraki
The KEK injector linac sequentially provides beams, and transfers them to the following four storage rings: a KEKB low-energy ring (LER) (3.5 GeV/positron), a KEKB high-energy ring (HER) (8 GeV/electron), a Photon Factory ring (PF ring; 2.5 GeV/electron), and an Advanced Ring for Pulse X-rays (PF-AR; 3 GeV/electron). So far, beam injection to the PF ring and PF-AR is carried out twice a day, whereas the KEKB rings are operated in the continuous injection mode (CIM) so that the stored current remains almost constant. The KEK linac upgrade project has been started since 2004 so that the PF top-up and KEKB CIM can be performed at the same time. The aim of this upgrade is to change the linac parameters up to 50 Hz, which is the maximum linac beam repetition rate, by using a multi-energy-linac scheme. This upgrade has been successfully completed. The simultaneous top-up operation for three rings has stably been carried out since this April. We will report the simultaneous top-up injection for the KEKB and PF rings in detail.
KEK, Ibaraki
The next generation B-factory 'SuperKEKB' project whose target luminosity is 8 ×1035 cm-2s-1 is under consideration. A 'nano-beam scheme' is introduced to the SuperKEKB. In the scheme, an electron beam (Energy = 7 GeV, Charge = 3-4 nC/bunch, Vertical emittance =2.8 x 10-5 m) and a positron beam (Energy = 4 GeV, Charge = 4 nC/bunch, Vertical emittance = 1.6 x 10-5 m), are required at the end of injector linac. They are quite challenging targets for the present linac. In order to meet the requirements, we will introduce some new components to the linac. They are a photo-cathode RF gun for an electron beam, a positron capture section using new L-band cavities, a newly designed positron-generation target system and a damping ring for a positron beam. This presentation shows a strategy of our injector upgrade.
The University of Tokyo, Nuclear Professional School, Ibaraki-ken
University of Tokyo, Tokyo
We are commissioning the cathode, Na2KSb at the wavelength of 266, 400 nm with thermo-mechanically modified structure and improved vacuum system (2·10-08 Pa). We could improve RF reflection waveform and obtain the maximum energy of 22 MeV. We estimate the electrical field of 50 MV at the cathode. So far, we have obtained the quantum efficiencies of 1.1, 0.01% and the maximal charges of 4.6, 1 nC for 266, 400 nm. We are observing and checking carefully individual difference of QE of the cathodes for 266, 400 nm, and we have obtained 22 MeV energy. This new RF photocathode RF gun system has been already used for subpicosecond time-resolved radiation chemistry.
PKU/IHIP, Beijing
As part of the updated DC-SC injector, a 3.5cell cavity has been fabricated at Peking University, which includes two Coaxial High Order Mode (HOM) couplers. The effect of the HOM couplers has been studied by numerical simulation and measurement. The results are highly uniform and show that the two couplers do effectively damp the HOMs.
CERN, Geneva
SLAC, Menlo Park, California
In this paper, we present a lattice design for the Large Hadron Electron Collider (LHeC) recirculating Linac. The recirculating Linac consists of one roughly 3km long linac hosting superconducting RF (SRF) accelerating cavities, two arcs and one transfer line for the recirculation. Electron beam will have two passes in the SRF linac to get a maximum energy of 140 GeV, or have four passes with a maximum energy of 60 GeV (two for acceleration and two for deceleration) in the Energy Recovery Linac (ERL) option.
CERN, Geneva
SLAC, Menlo Park, California
In this paper, we estimate the emittance growth in the LHeC recirculating Linac, the lattice design of which is presented in another paper of IPAC10 proceedings. The possible sources for emittance growth included here are: energy spread from RF acceleration in the SRF (superconducting RF) linac plus large chromatic effects from the lattice, synchrotron radiation (SR) fluctuations in the recirculating arcs. 6-D multi-particle tracking is launched to calculate the emittance from the statistical point of view. The simulation results are also compared with a theoretical estimation.
NSRRC, Hsinchu
National Chiao Tung University, Hsinchu
NTHU, Hsinchu
A 25-30 MeV S-band linac system that equipped with thermionic cathode rf gun is being constructed at NSRRC for generation of ultrashort relativistitic electron beam. According to simulation studies, high quality GHz repetition rate electron pulses of about 50 pC as short as few tens fsec can be produced. This injector system will be used as the driver for experiments on fsec head-on inverse Compton scattering X-ray source and high power wake field microwave sources. The progress of our construction work will be presented.
CERN, Geneva
Royal Holloway, University of London, Surrey
We report on a study of muon backgrounds in CLIC. For this we combined halo and tail generation using HTGEN with detailed tracking by BDSIM of impacting halo particles and resulting secondaries from the collimation spoilers to the detector.
ANL, Argonne
SLAC, Menlo Park, California
Northern Illinois University, DeKalb, Illinois
We report on the design of a 7 cell, standing wave, 1.3 GHz LINAC cavity and the associated beam dynamics studies for the upgrade of the drive beamline for the Argonne Wakefield Accelerator (AWA) facility. The LINAC design is a compromise between single bunch operation (100 nC @ 75 MeV) and minimizing the energy droop due to beam loadning along the bunch train during bunch train operation. The 1.3 GHz drive bunch train target parameters are: 75 MeV, 10-20 ns macropulse duration, 16x60nC microbunches; this is equivalent to a macropulse current and beam power of 80 Amps and 6 GW, respectively. Each LINAC structure accelerates approximately 1000 nC in 10 ns by a voltage of 11 MV at an RF power of 10 MW. Due to the short bunch train duration desired (~10 ns) and the existing frequency (1.3 GHz), compensation of the energy droop along the bunch train is difficult to accomplish with the two standard techniques: time-domain or frequency-domain beam loading compensation. Therefore, to minimize the energy droop, our design is based on a large stored energy LINACs. In this paper, we present our LINAC optimization method, detailed LINAC design, and beam dynamics studies of the drive beamline.