NSRRC, Hsinchu
Lots of multipole magnets will be fabricated for the accelerator lattice magnets of Taiwan Photon Source (TPS) that include the storage ring magnets, booster ring magnets, and the transfer line magnets. Therefore, several precise rotating-coil measurement systems (RCS) with high speed measurement are developed to characterize the magnetic field of quadrupole (QM) and sextupole (SM) magnets. Printed circuit coil including normal-coil and bucking-coil, are applied to measure the absolute and relative values of multipole components, respectively. Normal-coils with three turns (single-layer-coil) has been previously discussed and found to have good reproducibility. Moreover, a 12-turn multi-layer-coil has been designed to characterize the booster ring multipole magnets of TPS. This study, compares the compensatory characteristics of two bucking-coils with 75/150 turns and 150/300 turns with those of normal-coil. A continuously-winding-method for bucking-coil is presented in the paper. A precision testing bench was used to test the performance of this system. This work describes the measurement system design and fabrication, and discusses the system precision and accuracy.
ANL, Argonne
HSRC, Higashi-Hiroshima
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
In the selection of a new insertion device optimized for producing intense soft x-rays at the Advanced Photon Source, two different types of circular polarizing quasi-periodic undulators were studied. The magnetic structure of the undulators consists of pure permanent magnets for one of the undulators (an APPLE-II style undulator) and of electromagnets and pole pieces for the other type. The undulator period lengths were chosen so that the first harmonic energy occurs at 200 eV in linear horizontal polarization mode and at 400 eV in both linear vertical and circular polarization modes. Calculations of on-axis brilliance and on-axis flux spectra for both types of undulators and reductions of the spectral harmonics due to quasi-periodicity are presented. The introduction of quasi-periodicity of the magnetic fields shifts the higher spectral harmonics to a lower energy, hence reducing the so-called higher-order contamination dramatically. At the same time however, it reduces the first harmonic intensity by 20 40%. The non-sinusoidal shape of the horizontal and vertical magnetic fields of the electromagnetic undulator at high K values enhances the intensity of the first harmonic.
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.
A superconducting planar undulator is under development at the Advanced Photon Source (APS). The initial R&D phase of the project includes intensive magnetic modeling performed with the Opera 2d and 3d software packages. This simulation addresses questions of magnetic design of the undulator including calculation of peak field on the undulator axis and maximum field in the conductor, superconductor load line optimization, and design of the undulator ends and correction coils. Results of the magnetic simulation are presented in the paper.
ANL, Argonne
Fermilab, Batavia
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An extensive R&D program is underway at the Advanced Photon Source (APS) with the aim of developing a technology capable of building a 2.4-m-long superconducting planar undulator for APS users. The initial phase of the project concentrates on using a NbTi superconductor and includes magnetic modeling, development of manufacturing techniques for the undulator magnet, and design and test of short prototypes. The current status of the R&D phase of the project is described in this paper.
ANL, Argonne
HSRC, Higashi-Hiroshima
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A request from the light source user community for insertion devices that provide only monochromatic light has led to development of quasi-periodic undulators (QPUs). These devices generate shifted harmonics in the photon energy spectrum, thus allowing suppression of higher harmonics by optical monochromator systems. Until now such undulators have been technically realized with pure permanent magnets or with hybrid structures. A concept for a superconducting quasi-periodic undulator (SCQPU) is suggested and described in this paper.
ANL, Argonne
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract number DE-AC02-06CH11357.
Investigation into a circular polarizing quasi-periodic undulator is presented here. Electromagnets are used to generate the vertical field. Permanent magnets are used to generate the horizontal field. Calculated maximum effective vertical and horizontal magnetic fields on the undulator axis higher than 8.5 kGauss are achieved at a 10.5-mm gap for a 9-cm-period undulator. Fields of this magnitude are difficult to achieve in purely electromagnetic devices. Switching the sign of the current for the vertical field electromagnets allows for right- or left-handed circular polarization. A laminated core can be introduced to allow for fast helicity switching in order to utilize lock-in detection techniques. Quasi-periodicity can be introduced in the vertical electromagnet field by reducing the current at the quasi-periodic poles and can be turned on, off, or somewhere in between. Quasi-periodicity can be introduced in the horizontal permanent magnet field by inserting weakened magnets at the quasi-periodic poles. Since it is built into the magnet structure, this quasi-periodicity cannot be turned off.
BNL, Upton, Long Island, New York
Funding: Work performed under the auspices of U.S. Department of Energy, under contract DE-AC02-98CH10886
National Synchrotron Light Source II is a 3-GeV, 792-meter circumference, high-flux and high-brightness synchrotron radiation facility being constructed at Brookhaven National Laboratory. The storage ring vacuum chambers are made of extruded aluminium and the bending magnet photons are intercepted at discrete photon absorbers. The design of the storage ring vacuum system will be presented, with emphasis on vacuum chamber design and fabrication, pumping arrangements, photon beam tracking and absorber positioning, and interface with other accelerator systems. The evaluation of the aluminium chamber prototypes and RF shielded bellows will also be described.
CLASSE, Ithaca, New York
Funding: Work supported by the National Science Foundation, the US Department of Energy, and the Japan/US Cooperation Program
In concert with the ILC global design effort, the CESR is being converted into ILC Damping Ring Test Accelerator. The vacuum system is undergoing staged reconfigurations to support both the CesrTA physics goals and the CHESS X-ray sources. Six superconducting wigglers were moved to a sector with zero-dispersion. The sector is densely populated with beam instrumentation and diagnostic devices. A new photon stop chamber will be used to handle the high synchrotron radiation power generated from the SCWs at high positron beam energy. A 12-m long gate-valve isolated straight sector was created in a second location, where many electron-cloud diagnostic chambers will be installed and tested. We also configured two very short sections in the arcs, with additional gate valves, to provide flexibility of exchanging various meter-long test chambers with minimum impact to the operations. Many retarding field analyzers were integrated into the vacuum modifications in SCWs, dipoles, and drifts to study EC growth and suppression techniques. Creating environments where both local and collaborator provided equipment can be easily installed has been a major objective in the modifications.
NSRRC, Hsinchu
National Synchrotron Radiation Research Center (NSRRC) will build a new 3GeV, 400mA synchrotron accelerator machine. Several different IDs have been proposed and the corresponding front ends are designed. Beam lines of IU20, IU28, SW48 and EPU70 will be the phase I requirement. Due to different power load and density flux, fixed masks, photon absorber, slits, photon absorber and photon beam position monitor will all be customized to meet the beam line user requirements as well as the thermomechanical limits. Overall front end layout, analysis results of the high heat load components are illustrated; experiments of photon beam position monitor, front end pressure distribution due to thermal and photon stimulated desorption outgassing analysis, are also presented in this paper.
NSRRC, Hsinchu
Front End (FE) is the first area shapes radiation power to suit the need not only for protection but also for the beam line uses. About 14m long FE vacuum system will connect the ultra high vacuum (UHV) storage ring and beam line in Taiwan Photon Source (TPS). The Fixed mask (FM), photon absorber (PAB) and slit are the major high gas load components, especially in insertion Devices (ID) front ends, because of the synchrotron radiation. From the P(pressure)=Q(outgas)/S(pump) formula, there are some issues will be concerned to get lower vacuum pressure: The low outgassing rate of the vacuum chamber (Qthermal), the localization of the the pumps (IP and NEG) to pump down the outgassing of the photon simulated desorption(Qpsd), and the arrangement of the aperture and gas load . The basic pressure distribution of the bending magnet (BM) and ID front ends will be discussed.
USTC/NSRL, Hefei, Anhui
IHEP Beijing, Beijing
TiN coating has been widely applied in surface treatments of particle accelerator vacuum chambers because of its characteristics such as good electrical conductivity, stability of performance, ability to block hydrogen permeation, low SEY, etc. With DC sputtering, TiN film has been coated on the inner face of a stainless steel pipe vacuum chamber, 86 mm in diameter and 2300 mm in length. The vacuum performances testing of the coated chamber has also been done, including thermal outgassing rate measurement, PSD measurement, and SEY measurement of samples. Compared with those of uncoated stainless steel chamber, the results show that coating TiN film is a very effective method of the treatment of particle accelerator vacuum chamber.
DESY, Hamburg
INFN/LASA, Segrate (MI)
BESSY GmbH, Berlin
DESY Zeuthen, Zeuthen
Caesium telluride (Cs2Te) photocathodes are used as sources for electron beams because of their high quantum efficiency (QE) and their ability to release high peak current electron bunches in a high gradient RF-gun. A rapid unexpected decrease of the initial QE, from 10% to values below 0.5% in only a few weeks of operation, was observed. In XPS measurements we identify a peak of Fluorine possibly originating from Teflon. After identification and removal of this specific contaminant, the life time of the cathodes increased to several months. In addition we have investigated the response of fully functional photocathodes to extensive usage, bad vacuum conditions, and oxidation by means of XPS measurements. The experiments - carried out at the ISISS and the PM3 beam lines at the synchrotron facility BESSY compare the chemical composition and electronic structure of freshly prepared, contaminated, used, and oxidised Cs2Te cathodes.
Technion, Haifa
Funding: This work was supported by the Israel Science Foundation and the Kidron Foundation
We present results of an analysis demonstrating that electrons oscillating in a Penning trap may drain the energy stored in an adjacent active medium. For this process to happen, the electrons must become bunched and the energy imparted to the electrons allows them to leave the trap resulting into a train of bunches. Their angular frequency corresponds to medium’s resonance.
INFN/LASA, Segrate (MI)
Funding: This work has partly been supported by the European Community, Contract Number RII3-CT-2004-506008.
Since ‘90s our laboratory is in charge of producing Cs2Te photocathodes employed as laser driven electron sources in the high brightness photoinjectors of the FLASH and PITZ facilities. The production recipe has been developed and standardized during years, fulfilling the requests for photocathode operation in the photoinjectors. Nevertheless, the growing process of the film is still not totally understood, mainly respect to the final material properties. In this paper, reflectivity and spectral response measurements, at different wavelengths, measured during the photocathode growth are presented and compared with the corresponding photocurrent behavior. The new information, together with results obtained with standard diagnostic tools, will help to improve the understanding of the growing process, of the compounds formation with different Cs/Te ratio and of the reproducibility of the Cs2Te film structure.
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
A model has been created in Geant4 to simulate the key elements of an undulator-based positron source for CLIC: the goal is to consider such a source as an alternative to the present baseline concept. The parameters of the undulator and capture device have been optimized for a range of operating scenarios. In each case we have calculated the rate of positron production, positron polarization and capture efficiency. We discuss the strengths and weaknesses of the undulator scheme in CLIC.
The University of Liverpool, Liverpool
Cockcroft Institute, Warrington, Cheshire
An undulator-based source has been chosen as a part of the baseline configuration for the International Linear Collider (ILC) to generate an intense beam of polarised positrons. A photon collimator placed between the undulator and the target can be used to adjust the size, intensity and polarisation of the photon beam impacting the target, and can also protect the target station and limit the activation of downstream components. In this paper, we calculate quantities such as the energy deposition, temperature change, activation and dose rate for different designs of the photon collimator, and consider the advantages and disadvantages for each case.
BNL, Upton, Long Island, New York
A new 3rd generation light source (NSLS-II project) is in the early stage of construction at Brookhaven National Laboratory. The NSLS-II facility will provide ultra high brightness and flux with exceptional beam stability. It presents several challenges in the diagnostics and instrumentation, related to the extremely small emittance. In this paper, we present an overview of all planned instrumentation systems, results from research & development activities; and then focus on other challenging aspects.
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.
ANL, Argonne
Funding: U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An investigation into development of a 200-kW CW solid state rf power system design to replace the existing klystron-based 352-MHz rf systems at the Advanced Photon Source has been started. The baseline 352-MHz solid state system design will consist of multiple 1-kW CW modules combined to produce a total output capability of 200-kW CW, sufficient to drive one single-cell storage ring cavity. A description of the 1-kW CW module building block of the solid state power sistem will be presented, along with results from hardware evaluation tests at the 1-kW CW level.
ANL, Argonne
JLAB, Newport News, Virginia
Funding: * Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A superconducting multi-cell cavity for the production of short x-ray pulses at the Advanced Photon Source (APS) has been explored as an alternative to a single-cell cavity design in order to improve the packing factor and potentially reduce the number of high-power RF systems and low-level RF controls required. The cavity will operate at 2815 MHz in the APS storage ring and will require heavy damping of parasitic modes to maintain stable beam operation. Novel on-cell dampers, attached directly to the cavity body, have been utilized by taking advantage of the magnetic field null on the equatorial plane in order to enhance damping. Design issues and simulation results will be discussed.
BNL, Upton, Long Island, New York
The extremely small photon beam dimensions of NSLS II impose challenging requirements on the e-beam orbital stability in the 6-D phase space. The electron beam orbit at the photon source locations must remain within a few hundred nanometer window for a wide frequency band. The beam orbit movement is coupled to the movement of the magnetic elements in the lattice which are itself coupled to the ring-building structure. While the vibration exciting the ring structure consists of deterministic and stochastic noise, it is the high frequency random, uncorrelated part that has the largest impact on the residual beam orbit movement as it is most difficult to control by fast orbit feedback. In this study, an analytical model is employed to quantify lattice displacement and beam orbit jitter for the expected conditions of NSLS II. The dynamic interaction of the ring supporting the lattice with the stationary ground vibration is addressed using a 3-D model of wave-structure interaction. Cross transfer functions linking ground vibration with the ring and magnetic lattice for various stochastic parameters are deduced leading to a multi-degree of freedom cross-spectral density of the lattice.
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.
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.
LBNL, Berkeley, California
BNL, Upton, Long Island, New York
Funding: Supported by DOE BES contract DE-AC03-76SF00098.
Several years ago experiments at the APS demonstrated the possibility of creating crabbed beam through vertically kicking the beam and letting it oscillate for a half of a synchrotron period. Such a crabbed beam would allow the possibility of creating a few ps xrays. At the ALS we have repeated these experiments. In this paper we will present the results obtained and compare them to theoretical predictions.
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 Zeuthen, Zeuthen
DESY, Hamburg
A first prototype of a switching mirror has been designed, built and tested. With a repetition rate of up to 2.5 Hz the mirror is used to provide different beam lines with the Laser light produced by FLASH. The repetition accuracy is in the order of 1 um whereas the yawing is about 1 arcsec.
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.
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.
RadiaBeam, Marina del Rey
Purdue University, West Lafayette, Indiana
UCLA, Los Angeles, California
Funding: This work is supported by the US Defense Threat Reduction Agency SBIR contract HDTRA1-08-P-0035.
Conventional X-ray sources used for medical and industrial imaging suffer from low spectral brightness, a factor which severely limits the image quality that can be obtained. X-ray sources based on Inverse Compton Scattering (ICS) hold promise to greatly improve the brightness of X-ray sources. While ICS sources have previously been demonstrated, and have produced high-peak brightness X-rays, so far experiments have produced low average flux, which limits their use for certain important commercial applications (e.g. medical imaging). RadiaBeam Technologies is currently developing a high peak- and average-brightness ICS source, which implements a number of improvements to increase the interaction repetition rate, as well as the efficiency and stability of the ICS interaction itself. In this paper, we will describe these improvements, as well as plans for future experiments.
ISSP/SRL, Chiba
KEK, Ibaraki
We successfully demonstrated a new beam injection method using a single pulsed sextupole magnet (PSM). The PSM has a parabolic-shaped magnetic field, which is expected to provide an effective kick to the injected beam without little effects on the stored beam. We installed the PSM injection system at the Photon Factory storage ring (PF-ring) and succeeded in injecting the beam into PF-ring and storing the current up to 450 mA. This is the first demonstration of the PSM beam injection in electron storage rings. We also tested top-up injection and confirmed that dipole oscillation of the stored beam was sufficiently reduced compared with that generated by the conventional injection system. In this conference, we will present the experimental results and the advantages of the PSM beam injection.
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
Lancaster University, Lancaster
STFC/RAL, Chilton, Didcot, Oxon
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
ANL, Argonne
Durham University, Durham
University of Bristol, Bristol
The ILC positron source relies upon a ~200 m long superconducting helical undulator in order to generate the huge flux of gamma photons required. The period is only 11.5 mm but the field strength is ~1 T. The UK is building and testing a full scale 4 m long ILC cryomodule at the moment. It will be completed in 2008 and the results used to demonstrate the feasibility of the full (200 m long) system.
NSRRC, Hsinchu
National Tsing Hua University, Hsinchu
The Taiwan Light Source (TLS), a third generation accelerator, has been operated successfully since 1993. It has been upgraded to increase the beam energy from 1.3 GeV to 1.5 GeV and the consequent capability of full energy injection afterwards. While the beam current has been increased from 200 mA to 300 mA after replacement of RF cavities with superconducting one. The vacuum pressure tends to decrease continuously after installations of 3 undulators and 4 wigglers as well as the new front ends. The accumulated beam dose increased faster up to > 14500 Ah after the routine operational top-up mode since 2006 with average pressure has been maintained below 0.13 nPa/mA. The beam life time of 6 hours at 300 mA has been kept with a limitation of Touschek life time at a stable beam with variation of photon flux < 0.05%. However, the photon absorbers of front ends have been replaced with new ones for subjecting the higher irradiation power after upgrading. The good dynamic pressure reflects the effective pumping performance. The experiences of components failures will be summarized in this paper.
IIT, Chicago, Illinois
Superconducting RF cavities are made of a thin metal shell (typically Niobium) with liquid Helium around it housed within another metal vessel. This geometry is effectively a Cerenkov radiator between two mirrors. Electrons stripped from the inner surface due to field emission can get accelerated by the electric field inside the cavity, punch through the cavity wall and still have enough energy to be faster than light in He. Detection of Cerenkov light generated by the electrons through an optical port integrated into the vessel can serve as a very sensitive diagnostic for field emission in cavity R&D and production as well as in operating superconducting linear accelerators. We report on simulation results for calculating the effective light yield in such a system to establish the feasibility of the technique.
NSRRC, Hsinchu
A superconducting accelerating RF cavity is going to be installed in 3GeV Taiwan Photon Source (TPS). It causes a reduction in bunch length in contrast with operation of normal type of RF cavity. A higher harmonic RF cavity is usually considered as an important tool to control the bunch length in the storage rings. The harmonic cavity in lengthening mode can also be helpful for improving the lifetime which is usually dominated in the storage rings by large angle intrabeam scattering (Touschek). In this paper we study the effects of third active harmonic cavity on bunch length of the TPS ring. We present the procedure, the simulation and the formulae to analyze the effects of third harmonic cavity on the rms bunch length while the main superconducting RF system is operated in 3MV. It is shown that the longitudinal rms electron bunches will lengthen up to 7.9 times for the optimum operation of the harmonic system.
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.
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.
YerPhI, Yerevan
Diffusive Radiation is originated by the passage of charged particles through a randomly inhomogeneous medium. DR appears when the conditions for multiple scattering of pseudophotons are fulfilled in the medium. Such a situation can be realized when a charged particle slides over a rough surface. One of the important properties of DR is that the maximum of emission lies at large angles from particle velocity direction. Therefore it can be used for detection of beam touch to the accelerators vacuum chamber wall in case when generated photons will be observed on the opposite side of vacuum chamber. Such a diagnostics can be especially useful for observation of storage rings beam halo.
FZK, Karlsruhe
Preliminary studies performed with the cold bore superconducting undulator installed in the ANKA storage ring suggest that the beam heat load is mainly due to the electron wall bombardment. Electron bombardment can both heat the cold vacuum chamber and induce an increase in the pressure because of gas desorption. In this contribution we compare the measurements of the pressure in a cold bore performed in the electron storage ring ANKA with the prediction obtained using the equations of gas dynamic balance in a cold vacuum chamber exposed to synchrotron radiation and electron bombardment. The balance results from two competitive effects: the photon and electron desorption of the gas contained in the oxide layer of the chamber wall and of the gas cryosorbed, and the cryopumping of the cold surface. We show that photodesorption alone cannot explain the pressure rise observed and that electron multipacting is needed.
HSRC, Higashi-Hiroshima
After the first demonstration of original quasi-periodic undulator (QPU) at the NIJI-IV*, there have been many modifications for QPU structures. One of the first most productive improvements was introducing the quasi-periodicity by modifying the magnetic field in a periodic undulator instead of modifying the period length**. In addition to this practical improvement, a slight modification of creation theory of one-dimensional quasi-periodicity gave another advantage for building this type of device. As the result, many different types of QPUs for generating both linearly and elliptically polarized radiations have been installed in the synchrotron radiation (SR) facilities worldwide. Furthermore, some more SR facilities are considering to building such devices in order to improve their performance. In the presentation, we will discuss about limitations and possible improvements of performance of QPU on the basis of synchrotron radiation physics and mathematics of quasi-periodicity.
*Kawai, et al, Proc. EPAC96, p.2549.
**Diviacco, Walker, ELETTRA Technical Note ST/M-TN-97/11, 1997, Chavanne, et al, Proc. EPAC98, p.2213, Diviacco, et al, ibid., p.2216.
Hiroshima University, Graduate School of Science, Higashi-Hiroshima
KEK, Ibaraki
A fast local bump system for the helicity switching of a circular/linear polarized undulator (CPU) has been developed at the Photon Factory storage ring (PF-ring). The system consists of five identical bump magnets and tandem APPLE-2 type CPUs. In addition, fast correction magnets for a leakage of the bump were prepared. We designed the bump magnets with a core length of 0.15 m, a pole gap of 21 mm and the coils of 32 turns, which were excited by bipolar power supplies with a capacity of ±100 A and ±50 V since a switching frequency of more than 10 Hz and a bump angle of 0.3 mrad were required for user experiments. The bump magnets and one of CPUs were installed at PF-ring in March 2008, and the experiments for the machine development using a stored beam have been progressed. In this conference, we present the first experimental results with the bump system.
SLRI, Nakhon Ratchasima
NSRRC, Hsinchu
Highest photon beam brightnesses are achieved in radiation from undulators. Very short period length and high fields, reached only in superconducting undulators, are desired to produce hard X-rays. In lower energy storage rings this is not enough, but radiation at higher harmonics(7th and up) are desirable. This is possible only if the undulator fields and periods are near perfect. Shimming methods as applied for room temperature permanent magnet undulators cannot be used for such superconducting magnets. The effect of field and period tolerances on higher harmonics photon beam brightnesses will be presented and limiting tolerances will be discussed. A variety of different field optimization techniques together with some measurements on test magnets will be discussed and evaluated to their usefulness as a high photon energy and high brightness radiation source.
UCLA, Los Angeles, California
BESSY GmbH, Berlin
LMU, München
The fundamentals of insertion device physics demand that to have access to ever higher photon energies either the beam energy must increase or the undulator period must decrease. Recent advances in accelerator technology have increased beam energies and at the same time insertion device technology has developed creative ways of producing light of the desired energy, characteristics and quality. This paper describes the simulation work for the design of a 9 mm period in-vacuum planar undulator using a new rare-earth magnetic material.
UCLA, Los Angeles, California
BNL, Upton, Long Island, New York
It is possible to obtain spectral and angular information of inverse Compton sources using only an x-ray imaging device and various foils with K-edges in the many keV energy range. Beam parameters are chosen such that on-axis photons are above the K-edge for a given material, where absorption is strong and there is relatively zero transmission. Photons observed off-axis are red-shifted and fall below the K-edge, therefore being transmitted and creating a “donut” pattern, or "lobes" in the ideal case for a circularly or linearly polarized laser, respectively. We present simulation and experimental results of the double differential spectrum (DDS) for angle and energy of Compton photons generated at the BNL ATF.
BNL, Upton, Long Island, New York
Funding: Work performed under the auspices of the US DOE.
A staged approach towards the development of a high energy RHIC-based electron-ion collider has been proposed in BNL*. In the first stage, a medium-energy electron-ion collider (MEeIC) would be constructed. It would utilize a high energy ion beam, accelerated in one of the two existing rings of the RHIC facility, colliding with a medium energy (4GeV) electron beam, generated by a proposed energy-recovery linac. As a part of the design and investigation of the interaction region, it is necessary to estimate the level of background radiation in the physics experiment detector. The primary radiation distribution can be readily calculated by employing electromagnetic theory. However, the secondary radiation is due to a diffuse scattering of soft X-ray off rough surfaces. In this paper, we first calculate the primary radiation spectrum and apply the kinematic Born approximation deduced from the scattering dynamics. Next, the diffuse scattering cross section is calculated as a function of the material and surface properties of the MEeIC vacuum system. Finally, the minimization of the radiation background level by the choices of the material and surface properties is discussed.
*V. Ptitsyn et al., “MEeIC - staging approach to eRHIC”, these proceedings.
UMAN, Manchester
CERN, Geneva
Uppsala University, Uppsala
The CLIC beam delivery system focuses 1.5 TeV electron and positron beams to a nanometre-sized cross section when colliding them at the interaction point (IP). The intense focusing leads to large beam-beam effects, causing the production of beamstrahlung photons, coherent and incoherent electron-positron pairs, as well as a significant disruption of the main beam. The transport of the post-collision beams requires a minimal loss extraction line, with high acceptance for energy deviation and divergence. The current design includes vertical bends close to the IP in order to separate the charged particles with a sign opposite to the main beam into a diagnostic-equipped intermediate dump, whilst transporting the photons and the main beam to the main dump. Photon and charged particle losses on the collimators and dumps result in a complex radiation field and IP background particle fluxes. In this paper, the electromagnetic backgrounds at the IP, which arise from these losses, are calculated, and the potential impact on the detector is discussed.
DESY, Hamburg
SLAC, Menlo Park, California
Funding: Work supported in part by the DOE under contract DE-AC02-76SF00515.
Different scenario of a start-up with international linear collider (ILC) are under discussion at the moment in the framework of the Global Design Effort (GDE). One of them assumes construction of the ILC in stages from some minimum CM energy up to final target of 500 GeV CM energy. Gamma-gamma collider with CM energy of 180GeV is considered as a candidate for the first stage of the facility. In this report we present conceptual design of a free electron laser as a source of primary photons for the first stage of ILC.
LLNL, Livermore, California
SLAC, Menlo Park, California
A high energy photon-photon collider can be created by the combination of electron linear accelerators with terawatt peak power lasers to create high energy photon beams through Commpton backscattering. The realization of this option requires of order 10kW of average laser power if each laser pulse is used once and discarded. Proposals for recirculating cavities to allow the laser light to be reused open the potential for laser systems with much lower required average power. We review the current status of laser technology and it's ability to realize a photon collider system.
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
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
After different wakefield test beams and radiation damage studies a prototype design for the International Linear Collider (ILC) spoilers of the betatron collimation system in the Beam Delivery System (BDS) is under development. Studies of activation and residual equivalent dose rate are needed in order to achieve an optimum design as well as to assess the radiation shielding requirements.
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.
UCLA, Los Angeles, California
Funding: This work was supported by The Department of Energy Grant No.DEFG02-92ER40727.
The self-guiding of relativistically intense but ultra-short laser pulses has been experimentally investigated as a function of laser power, plasma density and plasma length in the so-called "blowout" regime. Although etching of the short laser pulse due to diffraction and local pump depletion erodes the the head of the laser pulse, an intense portion of the pulse is guided over tens of Rayleigh lengths, as observed by imaging the exit of the plasma. Spectrally-resolved images of the laser pulse at the exit of the plasma show evidence for photon acceleration as well as deceleration (pump depletion)in a well defined narrow guided region. This is indicative of the self-guided pulse residing in the wake excited in the plasma. Energy outside the guided region was found to be minimized when the initial conditions at the plasma entrance were closest to the theoretical matching conditions for guiding in the blowout regime. The maximum extent of the guided length is shown to be consistent with the nonlinear pump depletion length predicted by theory.
USTRAT/SUPA, Glasgow
Instituto Superior Tecnico, Lisbon
University of Oxford, Oxford
STFC/RAL, Chilton, Didcot, Oxon
University of Oxford, Clarendon Laboratory, Oxford
University of Glasgow, Glasgow
Funding: EPSRC and EU Euroleap
Advances in laser-plasma wake field accelerators (LWFA) have now reached the point where they can be considered as drivers of compact radiation sources covering an large spectral range. We present recent results from the Advanced Laser Plasma High-energy Accelerators towards X-rays (ALPHA-X) project. These include the first ultra-compact gamma ray source producing brilliant 10fs pulses of x-ray photons > 150keV. We present new opportunities for harnessing laser-driven plasma waves to accelerate electrons to high energies and use these as a basis for ultra-compact radiation sources with unprecedented peak brilliance and pulse duration. We have demonstrated a brilliant tabletop gamma ray source based on enhanced betatron emission in a plasma channel which produces > 109 photons per pulse in a bandwidth of 10-20%. We present results of a compact synchrotron source based on a LWFA and undulator and discuss the potential of developing an FEL based this technology. Finally we discuss the plans for the Scottish Centre for the Application of Plasma-based Accelerator (SCAPA), which is being set up to develop and apply compact radiation sources, laser-driven ion sources and LWFAs.
IAC, Pocatello
This talk will focus on linear accelerators as the source for photon activation analysis (PAA) of environmental samples for climate change analysis (of particular interest), waste analysis (looking for toxic or recyclable metals before they go into a landfill), etc. Where relevant, US agencies and programs will be used as examples beyond the Idaho Accelerator Center to give a broad perspective of activities and opportunities in this field.
DESY, Hamburg
The free-electron laser facility FLASH at DESY, Germany is the world-wide unique SASE-FEL operating in the VUV and the soft X-ray wavelengths range. Since Summer 2005, FLASH operates as a user facility providing fully coherent 10 to 50 femtosecond long laser radiation in the wavelength range from 47 nm to 6.5 nm and with an unprecedented brilliance - many orders of magnitude higher than any other facility. The SASE radiation contains also higher harmonics. Several experiments have successfully used the third and fifth harmonics, in the latter case with a wavelength down to 1.59 nm. In addition, FLASH serves as a pilot facility for the European XFEL. Part of the beam time is reserved for general accelerator studies which also includes ILC related studies.
CLASSE, Ithaca, New York
LBNL, Berkeley, California
Funding: Support provided by the US National Science Foundation and the US Department of Energy
The Cornell Electron Storage Ring (CESR) has recently begun operation as a test accelerator for next generation linear collider damping rings. This program, known as CesrTA, includes a thorough investigation of synchrotron radiation generated electron cloud effects. CESR is capable of operating with a variety of bunch patterns and beam currents, as well as with both electron and positron beams. Understanding the buildup of the cloud under these conditions requires the use of well validated simulation programs. This paper will discuss three such programs- POSINST, ECLOUD and CLOUDLAND, which have been benchmarked against each other in parameter regimes relevant to CesrTA operating conditions, with the aim of understanding systematic differences in the calculations.
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02-06CH11357.
An array of fused-silica, fiber optic bundles has been built to spatially monitor e-beam loss in the APS storage ring (SR). A prototype beam loss position monitor (BLPM) has been installed on unoccupied undulator straight sections. The BLPM allows for 6 fiber bundles, 3 above and 3 below the beam. The center bundles are aligned with the beam axis. Presently, 4 bundles are used, 3 above and one in the center position below the beam. Each bundle is 3 m in length and composed of 61 220-micron-diameter fibers for a total aperture of 2 mm. The first 30 cm of each bundle are aligned parallel to the beam in contact with the vacuum chamber. Light generated by fast electrons within the fibers is thought to come primarily from Cerenkov radiation. The rest of the fiber acts as a light pipe to transmit photons to shielded PMTs. Tests show good signal strength during stored-beam mode from Touschek scattering and deterministic losses that occur during top-up injection and beam dumps. Post-injection loss signals show spatial and temporal dynamics. Simulation work is expected to provide calibration for integrated losses that can be compared with progressive undulator demagnetization.
BNL, Upton, Long Island, New York
Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract DE-AC02-98CH10886.
The NSLS-II Light Source being built at Brookhaven National Laboratory is expected to provide very small emittances and electron beam sizes. High resolution imaging systems are required in order to provide robust measurements. The pinhole cameras will utilize 5-fold magnification with a pinhole placed inside a crotch absorber. The pinhole is protected from high power synchrotron radiation with a filter made of refractory metal. In this paper we provide resolution analyses, heat load calculations, and optimization of NSLS-II pinhole cameras including beamline design.
BNL, Upton, Long Island, New York
Fermilab, Batavia
Funding: Work performed under the auspices of the US Department of Energy
SiO2 quartz fibers of the LHC ATLAS 0-degree calorimeter (ZDC) anticipated to experience integrated doses of a few Grad at their closest position were exposed to 200 MeV protons and neutrons at the BNL Linac. Specifically, 1mm- and 2mm- diameter quartz (GE 124) rods were exposed to direct 200 MeV protons during the first phase of exposure leading to peak integrated dose of ~28 Grad. Exposure to a primarily neutron flux of 1mm-diameter SiO2 fibers was also achieved with a special neutron source arrangement. In a post-irradiation analysis the quartz fiber transmittance was evaluated as a function of the absorbed dose. Dramatic degradation of the transmittance property was observed with increased radiation damage. In addition, detailed evaluation of the fibers under the microscope revealed interesting micro-structural damage features and irradiation-induced defects. This paper presents the results of the irradiation damage study.
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.
BNL, Upton, Long Island, New York
A gas fluorescence beam profile monitor has been realized at the relativistic heavy ion collider (RHIC) using the polarized atomic hydrogen gas jet. RHIC proton beam profiles in the vertical plane are obtained as well as measurements of the width of the gas jet in the beam direction. For gold ion beams, the fluorescence cross section is sufficiently large so that profiles can be obtained from the residual gas alone, albeit with long light integration times and lower number of Au ions than protons. We estimate the fluorescence cross-section of 100 GeV protons and Au ions on hydrogen gas to be 6.6x10-21 cm2 ~1.7x10-16 cm2, respectively*. We calculate the beam emittance to provide an independent measurement of the RHIC beam. This optical beam diagnostic technique, utilizing the beam induced fluorescence from injected or residual gas, represents a step towards the realization of a simple and truly noninvasive beam monitor for high-energy particle beams together with a wall-current-monitor system and/or a low light level optical temporal measurement system, a 3-dimensional particle beam profile system can be envisioned providing routine diagnosis of high-energy particle beams.
*T. Tsang, et. al., Rev. Sci. Instrum. 79, 105103 (2008).
CLASSE, Ithaca, New York
KEK, Ibaraki
Funding: NSF
We report on the performance goals and design of the CESRTA x-ray beam size monitor (xBSM). The xBSM resolution must be sufficient to measure vertical beam sizes under 20um. The xBSM images 2–4keV synchrotron radiation photons onto one-dimensional photodiode array. Instrumentation in the dedicated x-ray beam line includes upstream interchangeable optics elements (slits, coded apertures, and Fresnel zone plates), a monochrometer and the InGaAs photodiode detector. To provide sufficient x-ray flux in 2 GeV operation, the beam line is evacuated, with only a thin diamond window isolating the detector vacuum from the damping ring. The readout is a beam-synchronized FADC that is sufficient to measure consecutive bunches independently in a 4ns bunch spacing configuration.
CLASSE, Ithaca, New York
KEK, Ibaraki
Funding: NSF
Engineering data sets were collected with the CESRTA x-ray beam size monitor (xBSM) during November 2008 and January 2009 runs. We report on the performance of the InGaAs photodiode array detector, including time response and signal-to-noise. We report on the observed measurement resolution for changes in the damping ring vertical beam size using the interchangeable optics elements: slits, coded apertures, and a Fresnel zone plates. Observed resolutions are compared to predictions based on characteristics of the optics elements.
CERN, Geneva
The LHC collision rate monitors (BRAN) will be used to monitor and optimize the luminosity at the four interaction points (IP). Depending on the expected level of luminosity for a given IP two different designs have been developed for LHC. At IP1 and IP5, the high luminosity experiments, the BRAN consist of fast ionization chambers and at IP2 and IP8, where the collision rate will be smaller, they consist of fast polycristalline-CdTe detectors. A better understanding of the performances of those detectors can be provided by detailed tracking simulations of the collision products coming from the IP within the detector. Here we report about the results of simulations done with FLUKA as well as a comparison with measurements done in the SPS.
FEL/Duke University, Durham, North Carolina
TUNL, Durham, North Carolina
A gamma-ray beam produced by Compton scattering of a laser beam and a relativistic electron beam has been used to determine electron beam parameters. In order to accurately measure the electron beam energy, a fitting model based upon Compton scattering cross section is introduced in this paper. With this model, we have successfully determined the energy of the electron beam in Duke storage ring with a relative uncertainty of 3× 10-5 using a Compton gamma beam from the High Intensity γ-ray Source (HIγS) facility at Duke University.
KEK, Ibaraki
CLASSE, Ithaca, New York
UH, Honolulu, HI
Funding: Work supported in part by the US-Japan Cooperation Program
We are working on the development of a high-speed x-ray beam profile monitor for high-resolution and fast response for beam profile measurements to be used at CesrTA and SuperKEKB*. The optics for the monitor are based on a technique borrowed from x-ray astronomy, coded-aperture imaging, which should permit broad-spectrum, low-distortion measurements to maximize the observable photon flux per bunch. Coupled with a high-speed digitizer system, the goal is to make turn-by-turn, bunch-by-bunch beam profile measurements. Following initial tests with a low-resolution mask at large beam sizes (vertical size ~200 um), a high-resolution mask has been made for use with low-emittance beams (vertical size ~10 um) at CesrTA. The first performance results of the high-resolution mask on the low-emittance CesrTA beam are presented.
*J.W. Flanagan et al., Proc. EPAC08, Genoa, {10}29 (2008).
INFN/LNF, Frascati (Roma)
Università degli Studi di Firenze, Firenze
INOA, Firenze
VIGO System S.A., Ozarow Maz.
At the LNF (Laboratori Nazionali di Frascati) of the INFN a novel diagnostics experiment has been set-up to monitor the real time bunch behavior in the positron ring of the DAΦNE collider. The experiment has been installed on a bending magnet exit port of the e+ ring. The front-end consists of a UHV chamber where a gold-coated plane mirror deflects the radiation through a ZnSe window. After the window, a compact optical layout in air focuses the radiation on an IR detector. Compact mid-IR fast uncooled HgCdTe photodiodes are used to measure the bunch by bunch emission. A preliminary alignment of the mirrors and a first characterization of the radiation emitted have been performed. Longitudinal measurements of the bunch behavior, both in time and in frequency domain, obtained with fast IR detectors are presented. This novel diagnostics now available is ready to allow monitoring in real time of the bunch-by-bunch positron emission. It has been designed to improve the DAΦNE diagnostics with the main aim to identify and characterize positron bunch instabilities in the longitudinal plane. Developments for extending detection capability in the transverse planes are in progress.
Muons, Inc, Batavia
Northern Illinois University, DeKalb, Illinois
Funding: Supported in part by the Illinois Department of Commerce and Economic Opportunity
The multi-pixel photon counter (MPPC), or Geiger-mode avalanche photo-diode (GM-APD), also known as silicon photomultiplier (SiPM) is of great interest as a photon detector for high-energy physics scintillation counters, and other applications. In this paper we discuss some of the performance characteristics of MPPCs, and several applications, namely for muon cooling experiments, rare muon decay modes, and collider detectors. In addition we will discuss advances in signal processing electronics for MPPCs, which further enhance their use for large-scale applications.
KEK, Ibaraki
IN2P3-LAPP, Annecy-le-Vieux
ICEPP, Tokyo
University of Tokyo, Tokyo
The ATF2, accelerator test facility has been developed confirming techniques for obtaining super low emittance beam for future particle accelerators. Here, the converged beam size is designed to be 37 nm, and a precision beam size monitor using interference fringes as a reference called Shintake monitor is used for measuring it. In order to measure the beam size with resolution of better than 10%, relative position between the beam and the interference fringes should be stabilized within few nanometers. Highly rigid tables and mounts for the Shintake monitor and final focusing magnets are adopted with highly rigid floor to ensure relative position stability. Then, the Shintake monitor can be stabilized against the beam, since the beam fluctuates coherently with the final focusing magnets. On the other hand the interference fringes are stabilized against the Shintake monitor with precise phase control system. As a result, relative position between the beam and the interference fringes is stabilized based on rigidity of tables, mounts, and floor between them. We will present our conception for stabilization and results of vibration measurements for the Shintake monitor.
NSRRC, Hsinchu
Stability of photon beam intensity, I0, is one of the most important performance merits of a modern light source. The photon intensity measured at dragon beam line (BL11) is routinely used as a reference signal for I0 stability measurements. At NSRRC, a highly stable I0 intensity is maintained in most percentage of the user beam time. Meanwhile, glitches of I0 intensity up to few tens of percentage had been observed once every few operating hours, which was a puzzle before its reason had been identified later. A spontaneous large variation of photon intensity (I/I0) caused difficulties for users operating their experiments. Here, we report our development of a dedicated electronic circuit with functionality of single-gate, which was very helpful to clarify the puzzle of I0 glitches observed at NSRRC.
NSRRC, Hsinchu
Beam qualities include orbit stability and multi-bunch instability plays a crucial role for the operation of a synchrotron light source. To improve and to keep high beam quality, intensive correlation analysis is performed between data taken by electron BPMs and photon monitors. Efforts of this study will be summary in this report.
PAL, Pohang, Kyungbuk
A photon-beam-position-monitor (PBPM) is installed in a diagnostic beamline of the Pohang Light Source (PLS). From experience of existing PBPMs, we enriched our understanding of the synchrotron radiation and this understanding is fully considered for physical design of the new PBPM. The newly built PBPM is tested by using a high-power ultraviolet laser and its performance is checked before installation. Measurement results of beam position shows that the current (thermal) effect is reduced significantly and they also shows good agreement with results from a beam position monitor inside the PLS storage ring.
USTC/NSRL, Hefei, Anhui
The stability of synchrotron radiation source is of great significance for users, and an accurate and reliable photon beam position monitor (PBPM) is essential for success of synchrotron radiation experiments. Recently, we development a new PBPM called staggered pair photon beam position monitor for photon beam position measurement in Hefei Light Source (HLS). Its main advantage is to reduce the influence of bunch size. Usually, difference over sum (Δ/Σ) method is used to process the photon beam signal. Two new methods are put forward, which are a ratio method and a log-ratio method. For photon beam with Gaussian distribution, differences among methods of Δ/Σ, ratio and log-ratio are introduced. Some calculating results are given for three signal processing methods. Comparing those three methods of position signal processing, log-ratio method is found to have the widest range of linearity, and can obtain identical beam position with different bunch size. Based on that, we also compare staggered pair monitor with double-blade monitor. The staggered pair monitor is found to have higher sensitivity, as well it can ignore the influence of bunch size.
University of Tokyo, Tokyo
KEK, Ibaraki
ICEPP, Tokyo
Commissioning of the ATF/ATF2 project will start in the winter of 2008 to 2009, with the aim of studying beam optics, diagnostic instrumentations, and tuning processes for around 35 nm beam size. The project is the realistic scaled down model of the ILC final focus system, and also, studies in the project offered important findings for future accelerator physics. In this presentation, we will present about the status of the first commissioning of the Shintake monitor for ATF2. The monitor is located at the virtual interaction point of the ATF2 (the focus point) to measure beam size. A measurable ranges as a design are from 6 micron down to 20 nm in vertical and down to several microns in horizontal. That wide range allows us to used the detector from the beginning of the beam tuning process. The monitor scheme was originally proposed by T. Shintake and verified using around 60 nm beam at FFTB project. We upgraded the detector system for ATF2 of smaller beam size and implemented a laser wire scheme for horizontal beam size measurement. These additional capabilities are also presented.
SOLEIL, Gif-sur-Yvette
SOLEIL is the French 2.75 GeV high brilliance third generation synchrotron light source delivering photons to beam-lines since January 2007. Reaching micrometer to sub-micrometer level stability for the photon beams is then necessary but very challenging. Since September 2008, a fast orbit feedback has been running in daily operation. The performances of the system will be presented together with comparison with the ones previously achieved with the slow orbit feedback system. Status of the interaction of both feedback systems will be discussed. Moreover new X-BPMs have been installed on dipole and undulator based beam-lines; a total number of 9 vibration sensors (velocimeters) are now installed in the storage ring tunnel, on the experimental slab and outside the building in order to help to locate the different noise sources. Detailed results will be presented and debated.
MPQ, Garching, Munich
LMU, Garching
The author will review the remarkable world-wide field and activities of ultra-fast and exotic electron and photon sources and the science that can be accomplished through their use, as well as several specialized new sources of accelerated electrons. The areas to be covered include: the generation, manipulation and measurement of few-fs to sub-fs ultra-high phase space density electron bunches ({10}-{10}00 MeV) with ultra-intense waveform-controlled few-cycle light; the generation and measurement of few-fs to sub-fs hard X-ray pulses from the interaction of high-density electron bunches with periodic structures; laser wakefield accelerators and other exotic emerging sources; the use of these devices for science, including control and real-time observation of electron dynamics on atomic & sub-atomic scales.
CLASSE, Ithaca, New York
LBNL, Berkeley, California
ANL, Argonne
CalPoly, San Luis Obispo, CA
KEK, Ibaraki
SLAC, Menlo Park, California
Funding: National Science Foundation award 0734867 Office of Science, U.S. Department of Energy contracts DE-AC02-05CH11231 and DE-AC02-06CH11357
The Cornell Electron Storage Ring Test Accelerator (CesrTA) has commenced operation as a linear collider damping ring test bed following its conversion from an e+e- collider in 2008. A core component of the research program is the measurement of effects of synchrotron-radiation-induced electron cloud formation on beam dynamics. We have studied the interaction of the beam with the cloud in a number of experiments, including measurements of coherent tune shifts and emittance growth in various bunch train configurations, with different bunch currents, beam energies, beam emittance, and bunch lengths, for both positron and electron beams. This paper compares these measurements to modeling results from several advanced cloud simulation algorithms and discusses the implications of these comparisons for our understanding of the physics of electron cloud formation and decay in damping rings of the type proposed for future high-energy linear colliders.
PAL, Pohang, Kyungbuk
The prototypes of PBPM of the four blade types were installed in front-ends 1C1 diagnostic beam line. The four-blade PBPM measure both the horizontal and the vertical positions of the photon beam. KeithleyTM picoammeters are used to record the blade current. The position in both vertical and horizontal directions is calibrated by driving the stepping motors of the PBPM through an Industrial computer. PBPM Data Acquit ion Control System (DACS) is based on Window XP platform. The DACS is equipped with an Ethernet-to-GPIB controller (GPIB-ENET/00). Using the GPIB-ENET/100, networked computers can communicate with and control IEEE 488 devices from anywhere on an Ethernet-based TCP/IP network. This is GPIB interfaces four picoammeters and Ethernet-based TCP/IP communicates by Industrial Computer. Developing with LabVIEW for Windows XP, the interface to EPICS is accomplished by means of Win32 channel Access DLL's. Our LabVIEW application program incorporates EPICS-based motor control and PC-based data acquisition, using a National Instruments I/O board, and saves position data to txt files. This paper presents the PBPM DACS for PLS Control System.