Keyword: photon
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MOP064 Asymmetric Laser Radiant Cooling in Storage Rings electron, laser, damping, simulation 229
 
  • E.V. Bulyak
    NSC/KIPT, Kharkov, Ukraine
  • J. Urakawa
    KEK, Ibaraki, Japan
  • F. Zimmermann
    CERN, Geneva, Switzerland
 
  Laser pulses with small spatial and temporal dimensions can interact with a fraction of the electron bunches circulating in Compton storage rings. We studied synchrotron dynamics of such bunches when laser photons scatter off from the electrons with energy higher than the synchronous energy. In this case of ‘asymmetric cooling', as shown theoretically, the stationary energy spread is much smaller than under conditions of regular scattering; the oscillations are damped faster. Coherent oscillations of large amplitude may be damped in one synchrotron period, which makes this method feasible for injection the bunches into a ring in the longitudinal phase space. The theoretical results are validated with simulations.  
 
MOP071 Terahertz Light Source and User Area at FACET radiation, electron, linac, site 238
 
  • Z. Wu, A.S. Fisher, M.J. Hogan, S.Z. Li, M.D. Litos
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET at SLAC provides high charge, high peak current, low emittance electron beam that is bunched at THz wavelength scale during its normal operation. A THz light source based coherent transition radiation (CTR) from this beam would potentially be the brightest short-pulse THz source ever constructed. Efforts have been put into building this photon source together with a user area, to provide a platform to utilize this unique THz radiation for novel nonlinear and ultrafast phenomena researches and experiments.
 
 
MOP095 Experimental Determination of Damage Threshold Characteristics of IR Compatible Optical Materials laser, electron, site, accelerating-gradient 277
 
  • K. Soong, E.R. Colby, C. McGuinness
    SLAC, Menlo Park, California, USA
  • R.L. Byer, E.A. Peralta
    Stanford University, Stanford, California, USA
 
  Funding: Work funded by DOE contract DE‐AC02‐76SF00515 (SLAC)
The accelerating gradient in a laser-driven dielectric accelerating structure is often limited by the laser damage threshold of the structure. For a given laser-driven dielectric accelerator design, we can maximize the accelerating gradient by choosing the best combination of the accelerator’s constituent material and operating wavelength. We present here a model of the damage mechanism from ultrafast infrared pulses and compare that model with experimental measurements of the damage threshold of bulk silicon. Additionally, we present experimental measurements of a variety of candidate materials, thin films, and nanofabricated accelerating structures.
 
 
MOP207 Diamond X-ray Beam Position Monitors monitoring, diagnostics, undulator, insertion 483
 
  • J. Smedley, A. Heroux, J.W. Keister
    BNL, Upton, Long Island, New York, USA
  • K. Attenkofer
    ANL, Argonne, USA
  • J. Bohon
    Case Western Reserve University, Center for Synchrotron Biosciences, Upton, New York, USA
  • J. Distel
    LANL, Los Alamos, New Mexico, USA
  • M. Gaowei
    SBU, Stony Brook, New York, USA
  • E.M. Muller
    Stony Brook University, Stony Brook, USA
 
  Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under grant DE-FG02-08ER41547.
Modern synchrotrons are capable of significant per-pulse x-ray flux, and time resolved pulse-probe experiments have become feasible. These experiments provide unique demands on x-ray monitors, as the beam position, flux and arrival time all potentially need to be recorded for each x-ray pulse. Further, monitoring of “white” x-ray beam position and flux upstream of beamline optics is desirable as a diagnostic of the electron source. We report on a diamond quadrant monitors which provide beam monitoring for a variety of applications, for both white and monochromatic beams. These monitors have a position resolution of 20 nm for a stable beam, are linear in flux over at least 11 orders of magnitude, and can resolve beam motion shot-by-shot at repetition rates up to 6.5 MHz.
 
 
MOP214 Methods for Quantitative Interpretation of Retarding Field Analyzer Data simulation, electron, pick-up, positron 501
 
  • J.R. Calvey, J.A. Crittenden, G. Dugan, M.A. Palmer
    CLASSE, Ithaca, New York, USA
  • M.A. Furman
    LBNL, Berkeley, California, USA
  • K.C. Harkay
    ANL, Argonne, USA
 
  Funding: US Department of Energy grant DE-FC02-08ER41538 US National Science Foundation grant PHY-0734867
Over the course of the CesrTA program at Cornell, over 30 Retarding Field Analyzers (RFAs) have been installed in the CESR storage ring, and a great deal of data has been taken with them. These devices measure the local electron cloud density and energy distribution, and can be used to evaluate the efficacy of different cloud mitigation techniques. Obtaining a quantitative understanding of RFA data requires use of cloud simulation programs, as well as a detailed model of the detector itself. In a drift region, the RFA can be modeled by postprocessing the output of a simulation code, and one can obtain best fit values for important simulation parameters with a chi-square minimization method.
 
 
MOP238 Laser Compton Proton Polarimetry Revisited proton, laser, electron, scattering 560
 
  • A.N. Stillman
    Private Address, Huntington, USA
 
  Compton polarimetry of polarized proton beams is more feasible now than it was in 1995*, when I first estimated the laser requirements of a polarimeter using the available laser technology. New methods of high energy photon generation make the technique of Compton proton polarimetry a viable option for polarized proton beams. Since the analyzing power of a Compton polarimeter increases with photon energy and the count rate of the polarimeter increases with the laser intensity, the new laser technologies available today imply the construction of a working device with reasonable effort. I estimate the device parameters necessary for a working Compton polarimeter at RHIC using several methods of high energy photon generation.
* Arnold Stillman, in Proceedings of the 1995 Particle Accelerator Conference, 1995, p.2560
 
 
MOP273 Calibration and Simulation of the LCLS Undulator Beam Loss Monitors using APS Accelerators simulation, radiation, electron, undulator 618
 
  • J.C. Dooling, W. Berg, A.R. Brill, L. Erwin, B.X. Yang
    ANL, Argonne, USA
  • A.S. Fisher, H.-D. Nuhn, M. Santana-Leitner
    SLAC, Menlo Park, California, USA
 
  Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02-06CH11357
Electrons scattered by alumina ceramic transverse beam profile monitors inserted in the Advanced Photon Source (APS) booster-to-storage ring (BTS) transfer line are used to generate C ̆erenkov light for calibration of beam loss monitors (BLMs) installed in the Linac Coherent Light Source (LCLS) undulator beamline. In addition, gas bremsstrahlung (GB) photons generated by 7-GeV electrons in the APS sector 35 storage ring straight section are used to create pair-production electrons for measurement and calibration purposes. Both cases are modeled with the particle-matter interaction program MARS. The realized tuning fork geometry of the BLM exhibits regions of greater sensitivity in the radiator. Transverse GB beam scans have provided uniformity and sensitivity data throughout the volume of the radiator. Comparisons between predicted and measured signal strengths and thermoluminescent dosimeter readings are given and shown to be in reasonable agreement.
 
 
MOP276 Applying Cascaded Parameter Scan to Study Top-off Safety in NSLS-II Storage Ring injection, simulation, interlocks, storage-ring 627
 
  • Y. Li, S.V. Badea, W.R. Casey, G. Ganetis, R. Heese, H.-C. Hseuh, P.K. Job, S. Krinsky, B. Parker, T.V. Shaftan, S.K. Sharma, L. Yang
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by U.S. DOE, Contract No. DE-AC02-98CH10886
In this paper we introduce a new algorithm, the cascaded parameter scan method, to efficiently carry out the scan over magnet parameters in the safety analysis for the NSLS-II top-off injection. In top-off safety analysis, one must track particles populating phase space through a beamline containing magnets and apertures and clearly demonstrate that for all possible magnet settings and errors, all particles are lost on scrapers within the properly shielded region. In the usual approach, the number of tracking runs increases exponentially with the number of magnet settings. In the cascaded parameter scan method, the number of tracking runs only increases linearly. This reduction of exponential to linear dependence on the number of setpoints, greatly reduces the required computation time and allows one to more densely populate phase space and to increase the number of setpoints scanned for each magnet. An example of applying this approach to analyze an NSLS-II beamline, the damping wiggler beamline, is also given.
 
 
MOP304 Development of an X-Ray Beam Size Monitor with Single Pass Measurement Capability for CesrTA electron, optics, positron, controls 687
 
  • N.T. Rider, J.P. Alexander, M.G. Billing, J. Dobbins, R.E. Meller, M.A. Palmer, D.P. Peterson, C.R. Strohman
    CLASSE, Ithaca, New York, USA
  • J.W. Flanagan
    KEK, Ibaraki, Japan
 
  The CESR Test Accelerator (CesrTA) program targets the study of beam physics issues relevant to linear collider damping rings. This endeavor requires new instrumentation to study the beam dynamics along trains of ultra low emittance bunches. A key element of the program has been the development of an x-ray beam size monitor capable of collecting single pass measurements of individual bunches in a train over thousands of turns. This instrument utilizes custom, high bandwidth amplifiers and digitization hardware to collect signals from a linear InGaAs diode array. The digitizer is synchronized with the CESR timing system and is capable of recording beam size measurements for bunches spaced by as little as 4ns. The x-ray source is a bending magnet with Ec=0.6 keV during 2 GeV CesrTA operations. For these conditions the amplifier dynamic range was optimized to allow measurements with 3x109 to 1011 particles per bunch. Initial testing is complete. Data analysis and examples of key measurements which illustrate the instrument's performance are presented. This device offers unique measurement capabilities applicable to future high energy physics accelerators and light sources.  
 
TUOBS1 Technical Challenges in the Linac Coherent Light Source, Commissioning and Upgrades undulator, electron, linac, laser 724
 
  • Z. Huang, J.N. Galayda
    SLAC, Menlo Park, California, USA
  • P.A. Heimann
    LBNL, Berkeley, California, USA
 
  Funding: DOE
Five months after first lasing in April 2009, the Linac Coherent Light Source (LCLS) began its first round of x-ray experiments. The facility rapidly attained and surpassed its design goals in terms of spectral tuning range, peak power, energy per pulse and pulse duration. There is an ongoing effort to further expand capabilities while supporting a heavily subscribed user program. The facility continues to work toward new capabilities such as multiple-pulse operation, pulse durations in the femtosecond range, and production of >16 keV photons by means of a second-harmonic “afterburner” undulator. Future upgrades will include self-seeding and polarization control. The facility is already planning to construct a major expansion, with two new undulator sources and space for four new experiment stations.
 
slides icon Slides TUOBS1 [12.513 MB]  
 
TUOBS3 Status of the NSLS-II Project vacuum, storage-ring, injection, radiation 732
 
  • F.J. Willeke
    BNL, Upton, Long Island, New York, USA
 
  NSLS-II, the new 3 GeV 3rd generation light source presently under construction at Brookhaven National Laboratory will provide ultra-bright synchrotron radiation of 1021 photons s-1 mm-2 mrad-2 0.1% BW-1 at 2keV and high photon flux of 1015 photons s-1 0.1% BW-1. The facility will support a minimum of 60 beamlines. Construction started in 2009 and commissioning is expected to be completed in 2014. This report will provide a description of the NSLS-II design and will summarize the status of the construction project.  
slides icon Slides TUOBS3 [7.560 MB]  
 
TUOCS2 Accelerator Aspects of the Advance Photon Source Upgrade undulator, lattice, radiation, brightness 766
 
  • L. Emery, M. Borland, G. Decker, K.C. Harkay, E.R. Moog, R. Nassiri
    ANL, Argonne, USA
 
  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 13 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 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. In this paper, we discuss the evolutionary changes that are envisioned for the storage ring itself. These include short-pulse x-rays, long straight sections, superconducting undulators, improved beam stability, and higher current. With these and other changes, we anticipate significant improvements in capacity, flux, and brightness, along with the ability to perform unique time-resolved experiments.
 
slides icon Slides TUOCS2 [0.932 MB]  
 
TUOCS5 A Next Generation Light Source Facility at LBNL FEL, linac, electron, laser 775
 
  • J.N. Corlett, B. Austin, K.M. Baptiste, J.M. Byrd, P. Denes, R.J. Donahue, L.R. Doolittle, R.W. Falcone, D. Filippetto, D.S. Fournier, J. Kirz, D. Li, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, J. Qiang, A. Ratti, M.W. Reinsch, F. Sannibale, D. Schlueter, R.W. Schoenlein, J.W. Staples, T. Vecchione, M. Venturini, R.P. Wells, R.B. Wilcox, J.S. Wurtele
    LBNL, Berkeley, California, USA
  • A.E. Charman, E. Kur
    UCB, Berkeley, California, USA
  • A. Zholents
    ANL, Argonne, USA
 
  Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The Next Generation Light Source (NGLS) is a design concept, under development at LBNL, for a multi‐beamline soft x‐ray FEL array powered by a 2 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. The CW superconducting linear accelerator is supplied by a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for EEHG, HGHG, SASE, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds.
 
slides icon Slides TUOCS5 [4.758 MB]  
 
TUODS1 MaRIE X-Ray Free-Electron Laser Pre-Conceptual Design emittance, electron, undulator, cathode 799
 
  • B.E. Carlsten, C.W. Barnes, K. Bishofberger, L.D. Duffy, C.E. Heath, Q.R. Marksteiner, D.C. Nguyen, S.J. Russell, R.L. Sheffield, E.I. Simakov, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
  • R.D. Ryne
    LBNL, Berkeley, California, USA
 
  Funding: This work is supported by the U.S. Department of Energy through the LANL/LDRD and MaRIE programs.
The proposed Matter-Radiation Interactions in Extremes (MaRIE) facility at the Los Alamos National Laboratory will include a 50-keV X-Ray Free-Electron Laser (XFEL), a significant extension from planned and existing XFEL facilities. To prevent an unacceptably large energy spread arising from energy diffusion, the electron beam energy should not exceed 20 GeV, which puts a significant constraint on the beam emittance. To achieve a sufficiently high gradient of 50 MV/m, an rf frequency of 11.424 GHz is considered. A 100-pC baseline design is presented along with advanced technology options to increase the photon flux and to generate longitudinal coherency through single-bunch optical seeding, pre-bunching the electron beam, and combinations of these techniques.
 
slides icon Slides TUODS1 [0.751 MB]  
 
TUP003 Beam Stop of Spiral2 Facility: Activation and Residual Dose Rate Calculations neutron, simulation, factory, shielding 811
 
  • A. Mayoral, M. García, D. López, F. Ogando, J. Sanz, P. Sauvan
    UNED, Madrid, Spain
 
  Funding: *SPIRAL 2 Preparatory Phase. European Strategy Forum on Research Infrastructures. Seventh Framework Programme Ref 212692 **The Spanish Ministery of Science and Innovation. Project ENE2009-07572
SPIRAL2 facility is expected to produce 5mA of deuterons at 40 MeV. A beam dump device (BD) has been designed to stop the beam. In this paper we assess the residual dose rates (RDR) in the BD room during beam-off phases. MCNPX was used to deal with deuterons transport and production and transport of secondary neutrons. Deuteron and neutron induced activation were computed using ACAB* and EAF2007. Decay gammas were transported using MCNPX to compute RDR. Dose rates at cooling times up to one year are presented, showing that it is mainly due to BD copper induced activation. The uncertainties in the results can be attributed to: i) the reliability of the d-Cu activation cross sections reactions, ii) the computational approach used to assess the neutron source. The troublesome radioisotopes from d-Cu and their formation reactions were identified. EAF2007 cross sections for these reactions were compared with the available experimental data. Regarding the computational approach to determine the neutron source from d-Cu interactions two options were used: i) built-in nuclear models of MCNPX, ii) TENDL** and MCUNED***. The available experimental data were used for benchmarking.
* J. Sanz et al. ACAB. User’s manual NEA-1839 (2009)
** A.J. Koning et al. TENDL2008 http://www.talys.eu/tendl-2008/
*** P.Sauvan et al. Nucl. Instr.and Meth. A 614 (2010)3 323-330.
 
 
TUP013 A Concept Design of a Compton Scattering Light Source based on the HLS Electron Storage Ring electron, laser, scattering, storage-ring 835
 
  • X.C. Lai, H. Hao, H.Q. Huang, W.W. Li, X.Q. Wang, D.R. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: National Natural Science Foundation of China (Contract NO. 11045003)
Hefei Light Source (HLS) is a 2nd generation light source lasering high flux ultraviolet and soft x-ray with 200 MeV to 800 MeV electron beam. To explorer other applications of the electron storage ring of HLS, a concept design of Hefei Compton Scattering Light Source (HCSLS) is proposed. In this paper, Compton Scattring Simulation Code(CSSC), a parallel code based on the analytical method to simulate the Compton scattering between the laser beam and the electron beam, is presented. Using the CSSC, it is computed that HCSLS will produce photons with a total flux of 109 s-1 to 1011 s-1, and energy of 0.07 MeV to 1.15 MeV at the maximum spectral flux density with the 200 MeV to 800 MeV electron beam scattering with a kilo-watts CO2 laser. With a much shorter wave laser beam from an Nd:YVO4 laser, the scattered photons energy at the maximum spectral flux density is improved by a factor of 10, while its flux is reduce by a factor of 100 due to the lower peak laser power.
 
 
TUP124 Phase Contrast Imaging Using a Single Picosecond X-ray Pulse of the Inverse Compton Source at the BNL Accelerator Test Facility brightness, electron, scattering, laser 1062
 
  • M. Carpinelli
    Università di Sassari and INFN, Sassari, Italy
  • P. Delogu, M. Endrizzi
    INFN-Pisa, Pisa, Italy
  • B. Golosio, P. Oliva
    INFN-Cagliari, Monserrato (Cagliari), Italy
  • I. Pogorelsky, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
 
  Inverse Compton scattering (ICS) X-ray sources are of current interest due to their novel features that enable new methods in medical and biological imaging. As a compelling example of such a possibility, we present an experimental demonstration of single shot inline phase contrast imaging using the ICS source located at the BNL Accelerator Test Facility. The phase contrast effect is clearly observed in the images obtained. Further, its qualities are shown to be in agreement with the predictions of theoretical models through comparison of experimental and simulated images of a set of plastic wires of differing composition and size. We also display an example of application of the technique to single shot phase contrast imaging of a biological sample.  
 
TUP161 Quench Properties of Two Prototype Superconducting Undulators for the Advanced Photon Source undulator, power-supply, status 1121
 
  • C.L. Doose, M. Kasa, S.H. Kim
    ANL, Argonne, USA
 
  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 quench properties of two 42-pole prototype superconducting undulators (SCUs) (one having a steel core the other with an aluminium core) have been tested. Since the SCUs have relatively low stored energy, the quench protection has relied on an over-voltage protection feature of the power supply, and the inherent quench back from the core. Concerns about conductor damage (during a quench) due to heating and high induced voltages were raised. The maximum conductor temperatures and voltages have been deduced from voltage and current measurements during a quench. The deduced maximum hot-spot temperature of the conductor was less than 150 K and the maximum voltage across each SCU coil was less than 300 V.
 
 
TUP188 A New Power Supply System for the IEX Project at the APS power-supply, undulator, polarization, controls 1178
 
  • B. Deriy, M.S. Jaski, J. Wang
    ANL, Argonne, USA
 
  A new beamline providing circularly polarized x-rays that will cover photon energies from 250 eV to 2.5 keV is under development at the APS. Because of the unique requirements of the circular polarizing undulator constructed for this beamline, a new power supply system design is required. The undulator will contain twelve sets of electromagnetic coils – two main, two quasi-periodic, and eight correctors. The undulator will incorporate variable polarization control and reduction of the magnetic fields at so-called quasi-periodic pole locations for the purpose of suppressing the higher-order radiation harmonics. The challenges met in the power supply system design for the project will be discussed.  
 
TUP211 Compensation of Fast Kicker Rolls with Skew Quadrupoles kicker, injection, quadrupole, coupling 1208
 
  • I. Pinayev
    BNL, Upton, Long Island, New York, USA
 
  The development of the third generation light sources lead to the implementation of the top-up operation, when injection occurs while users collect data. The beam excursions due to the non-closure of the injection bump can spoil the data and need to be suppressed. In the horizontal plane compensation can be achieved by adjusting timing and kick amplitudes. The rolls of the kicker magnets create non-closure in the vertical plane and usually there is no means for correction. In the paper we describe proposed compensation scheme utilizing two skew quadrupoles placed inside the injection bump.  
 
TUP219 Temperature-Dependent Calibration of Hall Probes at Cryogenic Temperature vacuum, alignment, undulator, cryogenics 1223
 
  • M. Abliz, C.L. Doose, Y. Ivanyushenkov, I. Vasserman
    ANL, Argonne, USA
 
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Short-period superconducting undulators (SCUs) are presently being developed for the Advanced Photon Source. Field measurements of the SCUs will be performed at 4.2 K and near 300 K, so temperature-dependent calibration of the Hall probes is necessary. The sensitivity of the Hall probes has been measured at temperatures from 5 K to 320 K over a magnetic field range of ␣1.5 T. It was found that the sensitivity increased as the temperature decreased from 300 K to about 150 K. A specially designed probe assembly, with three Hall sensors for measuring both the horizontal and vertical field components, has been calibrated. The techniques for doing the calibration and the measurement results at various temperatures will be presented.
 
 
TUP227 Status of NSLS-II Storage Ring Vacuum Systems vacuum, multipole, dipole, radiation 1244
 
  • H.-C. Hseuh, A. Blednykh, L. Doom, M.J. Ferreira, C. Hetzel, J. Hu, S. Leng, C. Longo, V. Ravindranath, K. Roy, S.K. Sharma, F.J. Willeke, K. Wilson, D. Zigrosser
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work performed under the auspices of U.S. Department of Energy, under contract DE-AC02-98CH10886
National Synchrotron Light Source II (NSLS-II), being constructed at Brookhaven National Laboratory, is a 3- GeV, high-flux and high-brightness synchrotron radiation facility with a nominal current of 500 mA. The storage ring vacuum system has extruded aluminium chambers, with ante-chamber for photon fans and distributed NEG strip pumping. Discrete photon absorbers are used to intercept the un-used bending magnet radiation. In-situ bakeout is implemented to achieve fast conditioning during initial commissioning and after interventions.
 
 
TUP230 In-situ Secondary Electron Yield Measurement System at CesrTA electron, gun, vacuum, radiation 1253
 
  • Y. Li, J.V. Conway, S. Greenwald, J.-S. Kim, V. Medjidzade, T.P. Moore, M.A. Palmer, C.R. Strohman
    CLASSE, Ithaca, New York, USA
  • D. Asner
    Carleton University, College of Natural Sciences, Ottawa, Ontario, Canada
 
  Funding: Work Supported by NSF Grant #PHY-0734867 & DOE Grant #DE-FC02-08ER41538
Measuring the secondary electron yield (SEY) on technical surfaces in accelerator vacuum systems provides essential information for the study of electron cloud growth and suppression, with application to many accelerator R&D projects. As a part of the CesrTA research program, we developed and deployed an in-situ SEY measurement system. A two-sample SEY system was installed in the CesrTA vacuum system with one sample exposed to direct synchrotron radiation (SR) and the other sample exposed to scattered SR. The SEYs of both samples were measured as a function of the SR dosages. In this paper, we describe the in-situ SEY measurement systems and the initial results on bare aluminum (6061-T6), TiN-coated aluminum, amorphous carbon-coated aluminum, and amorphous carbon-coated copper samples.
 
 
TUP239 Development of a Super-Mini Undulator undulator, power-supply, electron, synchrotron 1274
 
  • A. Deyhim, J.D. Kulesza
    Advanced Design Consulting, Inc, Lansing, New York, USA
  • C. Diao, H.O. Moser
    SSLS, Singapore, Singapore
 
  This paper describes development and initial results for a small prototype of a superconducting undulator with a period less than 1 cm, referred to here as a “super-mini” undulator. The development of superconducting mini-undulators started in the early 1990s with work at BNL and KIT (Germany). In 1998, KIT demonstrated the first photon production with a super-mini of 3.8 mm period length *. This super-mini consisted of two coils wound bi-filarly in analogy to a solenoid. If such coils are arranged alongside each other, separated only by a small gap of the order of a couple of millimeters, a spatially alternating magnetic field is produced that makes a passing electron beam undulate and emit undulator radiation. Owing to the short period length, the photon energy is much higher than with conventional undulators at the same electron energy. Likewise, for a given photon energy, the electron energy can be much smaller entailing considerable cost savings of accelerator, building, and operations.
* T. Hezel, B. Krevet, H.O. Moser, J.A. Rossmanith, R. Rossmanith, and Th. Schneider, A superconductive undulator with a period length of 3.8 mm, J. Synchrotron Rad. 5(1998) pp. 448-450.
 
 
TUP241 End-Field Analysis and Implementation of Correction Coils for a Short-Period NbTi Superconducting Undulator undulator, simulation, alignment, emittance 1280
 
  • C.L. Doose, M. Kasa, S.H. Kim
    ANL, Argonne, USA
 
  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 short period superconducting undulator (SCU) is being developed at the Advanced Photon Source (APS). The on-axis field of the prototype 1.6-cm period 42-pole SCU0 was measured with a cryogenic Hall probe system. Typical permanent magnet undulators provide end-field correction by decreasing the strength of the magnets on both ends of each jaw. In the case of the SCU0, a set of correction coils was wound on the two end grooves of each of the steel cores along with the main coils to provide the required end fields. These correction coils were connected in series and energized with one power supply to provide simple and symmetrical operation. The measured phase errors of the SCU0 were below 2 degrees rms without any local magnetic tuning of the device.
 
 
TUP242 Electron Cloud Issues for the APS Superconducting Undulator electron, scattering, undulator, ion 1283
 
  • K.C. Harkay, Y. Ivanyushenkov, R. Kustom, E.R. Moog, E. Trakhtenberg
    ANL, Argonne, USA
  • L.E. Boon, A.F. Garfinkel
    Purdue University, West Lafayette, Indiana, USA
 
  Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS Upgrade calls for the development and commissioning of a superconducting undulator (SCU) at the Advanced Photon Source (APS), a 7-GeV electron synchrotron. Operation of an SCU at Angstromquelle Karlsruhe (ANKA), also an electron ring, suggests that electron multipacting is consistent with the observed heat load and pressure rise, but this effect is not predicted by an electron cloud generation code. At APS it was found that while the cloud code POSINST agreed fairly well with retarding field analyzer (RFA) data for a positron beam (operated 1996-98), the agreement was less satisfactory for the electron beam. The APS data suggest that the photoelectron model is not complete. Given that the heat load is a critical parameter in designing the cryosystem for the SCU and given the experience at ANKA, a study is underway to minimize the possible contribution to the heat load by the electron cloud at the APS, the photoelectrons in particular. In this talk, the results from POSINST are presented. Preliminary tracking of the photon flux using SYNRAD3D for the APS SCU chamber is presented, and possible ways to mitigate the photoelectrons are discussed.
 
 
TUP243 Development Status of a Magnetic Measurement System for the APS Superconducting Undulator undulator, status, wiggler, cryogenics 1286
 
  • Y. Ivanyushenkov, M. Abliz, C.L. Doose, M. Kasa, E. Trakhtenberg, I. Vasserman
    ANL, Argonne, USA
  • V.K. Lev, N.A. Mezentsev, V.M. Tsukanov
    BINP SB RAS, Novosibirsk, Russia
 
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Short-period superconducting undulators are being developed as part of the Advanced Photon Source (APS) upgrade program. The first test device is in fabrication. Before installation into the storage ring, the magnetic performance of the undulators will be characterized. The magnetic measurement facility routinely used for measuring and tuning conventional undulators cannot be employed for superconducting devices, so a new measurement system is being designed and built. The system is mechanically mounted on the undulator cryostat and uses a heated tube in the cold undulator bore to guide a Hall probe or measuring coils. A specially designed three-Hall sensor assembly allows measurement of the vertical and horizontal components of the magnetic field and the determination of the height of the magnetic midplane. A set of measuring coils is mounted on carbon-fiber tubes that can be translated and rotated in the undulator bore to measure the field integrals and their multipole components. The design of the measurement system and its construction status is described in this paper.
 
 
TUP244 Magnetic Simulation of an Electromagnetic Variably Polarizing Undulator * simulation, undulator, sextupole, polarization 1289
 
  • M.S. Jaski, R.J. Dejus, E.R. Moog
    ANL, Argonne, USA
 
  Development of an all-electromagnetic variable polarizing undulator is underway at the Advanced Photon Source (APS). This device has a set of Bx poles and coils and a set of By poles and coils. The Bx coils are powered separately from the By coils. Modifying the geometry of the Bx coils or poles changes not only the Bx field but changes the By field as well and vice-versa. Magnetic modeling with OPERA 3-D software was used to optimize the coil and pole geometries. Results of the magnetic field simulation and optimization are presented in this paper.
* Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract number DE-AC02-06CH11357.
 
 
WEOBS4 Improved Energy Changes at the Linac Coherent Light Source feedback, linac, electron, lattice 1424
 
  • N. Lipkowitz, H. Loos, C.R. Melton, G. Yocky
    SLAC, Menlo Park, California, USA
 
  The user requirements and beam time scheduling of the LCLS imposes a demand for fast changes in machine energy across the entire operating range of 3.3-15 GeV (480-10000 eV). Early operational experience during LCLS commissioning revealed this process to be problematic and error-prone, sometimes requiring substantial re-tuning at each change. To streamline the process, a software tool has been developed to gradually ramp the machine energy while the beam remains on, allowing beam-based feedbacks to continue to work during the energy change. The tool has considerably improved the speed and reliability of configuration changes, and also extends the capability of the LCLS, allowing for slow scans of the FEL photon energy over a wide range. This poster presents the basic process, analysis of the performance gains, and possible future improvements.  
slides icon Slides WEOBS4 [62.503 MB]  
 
WEP063 Tracking Particles Through A General Magnetic Field sextupole, lattice, storage-ring, HOM 1591
 
  • A. Xiao, M. Borland, L. Emery, Y. Wang
    ANL, Argonne, USA
 
  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 method that tracks particles directly through a general magnetic field described in a 3D field table was added to the code elegant recently. It was realized by converting an arbitrary particle's motion to a combination of free-drift motion and centripetal motion through the coordinate system rotation and using a general linear interpolation tool developed at the Advanced Photon Source (APS). This method has been tested by tracking particles through conventional magnetic elements (dipole, sextupole, etc.) to verify reference coordinate system conversions, tracking accuracy, and long-term tracking stability. Results show a very good agreement between this new method and the traditional method. This method is not designed to replace mature traditional methods that have been used in most tracking codes. Rather, it is useful for magnets with complicated field profiles or for studying edge effects.
 
 
WEP108 Application of Coherent Tune Shift Measurements to the Characterization of Electron Cloud Growth simulation, electron, radiation, vacuum 1680
 
  • D.L. Kreinick, J.A. Crittenden, G. Dugan, M.A. Palmer, G. Ramirez
    CLASSE, Ithaca, New York, USA
  • M.A. Furman, M. Venturini
    LBNL, Berkeley, California, USA
  • R. Holtzapple, M. Randazzo
    CalPoly, San Luis Obispo, California, USA
 
  Funding: DOE = DE-FC02-08ER41538 NSF = PHY-0734867
Measurements of coherent tune shifts at the Cornell Electron Storage Ring Test Accelerator (CesrTA) have been made for electron and positron beams under a wide variety of beam energies, bunch charge, and bunch train configurations. Comparing the observed tunes with the predictions of several electron cloud simulation programs allows the evaluation of important parameters in these models. These simulations will be used to predict the behavior of the electron cloud in damping rings for future linear colliders. We outline recent improvements to the analysis techniques that should improve the fidelity of the modeling.
 
 
WEP110 Electron Cloud Modeling for the ILC Damping Rings dipole, lattice, vacuum, electron 1686
 
  • J.A. Crittenden, D. Sagan
    CLASSE, Ithaca, New York, USA
  • K.G. Sonnad
    Cornell University, Ithaca, New York, USA
 
  Funding: Support by DOE contract DE-FC02-08ER41538 and NSF contract PHY-0734867
Electron cloud buildup is a primary concern for the performance of the damping rings under development for the International Linear Collider. We have performed synchrotron radiation profile calculations for the 6.4-km DC04 and 3.2-km DSB3 lattice designs using the SYNRAD utility in the Bmad accelerator software library. These results are then used to supply input parameters to the electron cloud modeling package ECLOUD. Contributions to coherent tune shifts from the field-free sections and from the dipole and quadrupole magnets have been calculated, as well as the effect of installing solenoid windings in the field-free regions. For each element type, SYNRAD provides ring occupancy, average beam sizes, beta function values, and beta-weighted photon rates for the coherent tune shift calculation. An approximation to the antechamber design has been implemented in ECLOUD as well, moving the photoelectron source point to the edges of the antechamber entrance and removing cloud particles which enter the antechamber.
 
 
WEP134 Depolarization and Beam-beam Effects at Future e+e Colliders polarization, positron, collider, undulator 1731
 
  • A.F. Hartin
    DESY, Hamburg, Germany
  • I.R. Bailey, C. Pidcott
    Lancaster University, Lancaster, United Kingdom
  • G.A. Moortgat-Pick
    University of Hamburg, Hamburg, Germany
 
  In order to exploit the full potential of proposed future high-energy electron-positron linear colliders, precise knowledge of the polarization state of the beams is required. In this paper we present an updated analysis of the depolarization effects caused by the intense beam-beam interaction, which is expected to be the dominant source of depolarization. The impact of higher-order effects are considered and numerical results from the Guinea-Pig and CAIN simulations are presented for the latest International Linear Collider (ILC) and Compact LInear Collider (CLIC) parameters.  
 
WEP162 Modeling of Diamond Based Devices for Beam Diagnostics electron, simulation, diagnostics, scattering 1794
 
  • D.A. Dimitrov, R. Busby
    Tech-X, Boulder, Colorado, USA
  • I. Ben-Zvi, J.W. Keister, T. Rao, J. Smedley
    BNL, Upton, Long Island, New York, USA
  • E.M. Muller
    Stony Brook University, Stony Brook, USA
 
  Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under grants DE-SC0004584 (Tech-X Corp.) and DE-FG02-08ER41547 (BNL).
Beamlines at new light sources, such as the National Synchrotron Light Source II will operate at flux levels beyond the saturation level of existing diagnostics, necessitating the development of new devices. Currently, there is no detector which can span the entire flux range that is possible even in a second generation light source and will become crucial for next generation light sources. One new approach* is a diamond-based detector that will be able to monitor beam position, flux and timing to much better resolution. Furthermore, this detector also has linear response to flux over 11 orders of magnitude. However, the successful development of the detector requires thorough understanding and optimization of the physical processes involved. We will discuss the new modeling capabilities we have been implementing in the VORPAL 3D code to investigate the effects of charge generation due to absorption of x-ray photons, transport, and charge trapping. We will report results from VORPAL simulations on charge collection and how it depends on applied field, charge trapping, and the energy of absorbed photons.
*J. W. Keister, J. Smedley, D. A. Dimitrov, and R. Busby, Charge Collection and Propagation in Diamond X-ray Detectors, IEEE Transactions on Nuclear Science, 57, 2400 (2010).
 
 
THOBS1 Developments in Superconducting Insertion Devices undulator, wiggler, electron, storage-ring 2077
 
  • E.R. Moog, Y. Ivanyushenkov
    ANL, Argonne, USA
 
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A number of superconducting wigglers are installed and in operation worldwide. Superconducting undulators, with their shorter periods and more demanding field quality requirements, present additional challenges and are still under development. Superconducting technology can produce a higher magnetic field strength on the beam axis than can a permanent-magnet-based undulator. This makes shorter period undulators feasible – they will still reach high enough field to have a reasonable photon energy tuning range. The shorter period device gives higher photon brightness at higher photon energies, opening up new opportunities for photon-hungry applications that require higher photon energies. Many light sources are interested in having a superconducting undulator; a few, including the Advanced Photon Source, have ongoing projects and are making significant progress. The status of these projects will be discussed.
 
slides icon Slides THOBS1 [3.427 MB]  
 
THP002 Re-Circulated Inverse Compton Scattering X-ray Source for Industrial Applications laser, electron, recirculation, cavity 2139
 
  • A.Y. Murokh, R.B. Agustsson, S. Boucher, P. Frigola, T. Hodgetts, A.G. Ovodenko, M. Ruelas, R. Tikhoplav
    RadiaBeam, Santa Monica, USA
  • M. Babzien, O.V. Chubar, T.V. Shaftan, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • I. Jovanovic
    Penn State University, University Park, Pennsylvania, USA
 
  An experiment is under way at the Accelerator Test Facility (ATF) at BNL to demonstrate inverse Compton scattering in a pulse-train regime. A photoinjector generated electron beam pulse train is scattered by a recirculating laser pulse in a novel resonant configuration termed Recirculation Injection by Nonlinear Gating (RING). The goal of the experiment is to demonstrate strong enhancement of the ICS photon flux through laser recirculation. The project status is presented, and the long-term outlook is discussed with emphasis on the medical and security applications.  
 
THP037 Design of an e-γ Converter for a 10 MeV Electron Beam target, electron, neutron, linac 2184
 
  • L. Auditore, D. Loria, E. Morgana
    INFN - Gruppo Messina, S. Agata, Messina, Italy
  • L. Auditore, R.C. Barnà, A. Trifirò, M. Trimarchi
    Università di Messina, Messina, Italy
  • G. Di Bella
    Università di Messina, Facoltà di Ingegneria, Messina, Italy
 
  In the last years, the INFN-Gruppo Collegato di Messina has designed and setup an x-ray source based on the 5 MeV electron linac hosted at the Dipartimento di Fisica - Università di Messina. In the meanwhile, and in the framework of an European funding, the group has setup the Centro Ricerche at Villafranca Tirrena (Messina, Italy) which holds a 10 MeV electron linac and which is, at the moment, mainly devoted to industrial Radiation Processing applications. Nevertheless, to the aim to provide also x-ray beams, an e-g converter has been designed by means of the MCNP4C2 simulation code and optimized for a 10 MeV electron beam. A wide investigation has been performed to choose material and thickness for the e-g converter in order to provide the highest x-ray yield. Then, angular distribution and energy spectrum have been simulated to characterize the produced bremsstrahlung beam. Also the target activation has been investigated. Finally, thermal analysis has been performed using a finite element model code, Deform 2D, to choose the definitive mechanical settings of the e-g converter.  
 
THP114 Status of the PEP-X Light Source Design Study emittance, FEL, linac, brightness 2336
 
  • R.O. Hettel, K.L.F. Bane, K.J. Bertsche, Y. Cai, A. Chao, X. Huang, Y. Jiao, C.-K. Ng, Y. Nosochkov, A. Novokhatski, T. Rabedeau, C.H. Rivetta, J.A. Safranek, G.V. Stupakov, L. Wang, M.-H. Wang, L. Xiao
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
The SLAC Beam Physics group and collaborators continue to study options for implementing a near diffraction-limited ring-based light source in the 2.2-km PEP-II tunnel that will serve the SSRL scientific program in the future. The study team has completed the baseline design for a 4.5-GeV storage ring having 160-pm-rad emittance with stored beam current of 1.5 A, providing >1022 brightness for multi-keV photon beams from 3.5-m undulator sources. The team is now investigating possible 5-GeV ERL configurations which, similar to the Cornell and KEK ERL plans, would have ~30 pm-rad emittance with 100 mA current, and ~10 pm-rad emittance with 25 mA or less. In the next year, a diffraction-limited storage ring using on-axis injection in order to reach 30 pm-rad or less emittance will be investigated. An overview of the PEP-X design study and SSRL’s plans for defining the performance parameters that will guide the choice of implementation options is presented.
 
 
THP120 Light Sources Optimized with Super Bends dipole, storage-ring, emittance, brightness 2342
 
  • L. Emery
    ANL, Argonne, USA
  • C. Steier
    LBNL, Berkeley, California, USA
 
  Funding: Work at Argonne was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357
In the past small storage rings with dipole-magnet-only sources were called second-generation light sources (before insertion devices (IDs) were used). With today's technology, e.g. superconducting dipole magnet of 5 T (e.g., ALS's Superbend *), one could make a smaller ring (say, 60-m circumference) with substantial brightness for dipole-magnet beams. Without IDs, these optimized sources would be designated as between second and third generation. Such rings don't exist yet, but their concept can be compared with other types of compact light sources. Typical parameters of such ring would be 60-m circumference, 2 GeV, several 5-T dipole sources in TME-like cells, and 4x1013 photons/s/0.1% BW at 1 Angstrom. The number of beamlines is variable, but potentially very large, only limited by funding.
* D. Robin et al., NIM A 538, 1-3, (2005), 65-92.
 
 
THP122 Comparison of Chirp Schemes for Short-Pulse X-ray Beams in Light Sources radiation, electron, insertion, insertion-device 2348
 
  • L. Emery, M. Borland, A. Zholents
    ANL, Argonne, USA
 
  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 is planning [*] to produce a short-pulse x-ray beam by way of rf deflecting cavities that locally impose a y'-t correlation on the stored beam at an insertion device. SPring-8 recently proposed [**] a variation on this scheme whereby the deflecting cavities impose a local y-t correlation on the stored beam. In one case the chirp is in the angle coordinate and in the other case the position coordinate. They both use slits to pass through a "short" portion of the photon beam. The practical limitations for the two schemes are discussed and compared, such as photon source size and angular divergence, storage ring apertures, and slit transmission.
* A. Nassiri et al., these proceedings
** T. Fujita et al., Proc. of IPAC10, p. 39
 
 
THP126 Obtaining Sub-Picosecond X-Ray Pulses in the Advanced Photon Source Using Laser Slicing laser, electron, wiggler, radiation 2357
 
  • A. Zholents, M. Borland
    ANL, Argonne, USA
 
  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 laser slicing technique* has been successfully applied at several low- to medium-energy storage ring light sources to create sub-picosecond pulses of x-rays. Application to high-energy storage rings has been considered problematic because of the required average laser power. However, because of on going advances in laser technology, this technique is now within reach at light sources like the Advanced Photon Source (APS), which operates at 7 GeV. In this paper, we analyze the potential performance of laser slicing at the APS, and compare it to alternatives such as deflecting cavities.
* R. W. Schoenlien et al., Science, 287, 2237(2000).
 
 
THP136 Short Pulse Generation by Laser Slicing at NSLSII laser, electron, lattice, wiggler 2381
 
  • L.-H. Yu, A. Blednykh, O.V. Chubar, W. Guo, S. Krinsky, Y. Li, T.V. Shaftan, G.M. Wang, F.J. Willeke, L. Yang
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by DOE contract DE-AC02-98CH10886.
We propose an upgrade R&D project for NSLSII to generate sub-pico-second short x-ray pulses using laser slicing. In this paper we discuss the basic parameters for this system and present a specific example for a viable design and its performance. Since the installation of the laser slicing system into the storage ring will break the symmetry of the lattice, we demonstrate it is possible to recover the dynamical aperture to the original design goal of the ring.
 
 
THP140 Synchrotron Light Options at Super-B brightness, radiation, undulator, synchrotron 2384
 
  • W. Wittmer, Y. Nosochkov, A. Novokhatski, J.T. Seeman, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  • M.E. Biagini, P. Raimondi
    INFN/LNF, Frascati (Roma), Italy
 
  The Super-B facility will collide electron and positron beams with different characteristics as done in the past at PEP-II and KEKB. The ring and electron (positron) beam characteristic of both high and low energy rings of the Super-B are comparable to NSLS-II and other state of the art synchrotron light sources. This suggests the use of this facility, either parasitically or in dedicated runs, as light source. In this paper we compare the characteristics of the synchrotron light generated at Super-B with existing, in construction and proposed facilities. We investigate different schemes to incorporate the generation of synchrotron radiation in the collider lattice design and look at different beam line layouts for users.  
 
THP152 Calibration of Spectrometers with Undulator Radiation undulator, radiation, electron, FEL 2402
 
  • S. Huang
    PKU/IHIP, Beijing, People's Republic of China
  • B. Jia, J.Y. Li, Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
 
  Funding: This work is supported in part by the U.S. Department of Energy, Office of Nuclear Physics under grant number DE-FG02-97ER41033
A well-calibrated spectrometer is critical for measuring the real spectra of spontaneous radiation of an electron beam in undulators (i.e. undulator radiation), which is important for FEL research. A calibration method of spectrometers based upon the known undulator radiation spectrum has been developed at Duke FEL Laboratory (DFELL). It has been used to provide a precise calibration for spectrometers from infrared (IR) to ultraviolet (UV). This calibration method is expected to be useful for the calibration of spectrometers working in the extreme ultraviolet (EUV) and X-ray region. In this work, we present the details of the calibration method and illustrate the usefulness of the method using a portable spectrometer in the visible region as an example.
 
 
THP156 Converting CESR into a Frontier Hard X-ray Light Source electron, focusing, undulator, collimation 2411
 
  • R.M. Talman, D. L. Rubin
    CLASSE, Ithaca, New York, USA
 
  Funding: NSF, DMR-0936384
The relatively large horizontal emittance εx of CESR, an electron storage ring designed for colliding beam operation, does not limit its performance after its conversion into a frontier x-ray source, CESR-X. Its flexible lattice optics permits the production of hard x-ray beams competitive with any in the world by exploiting the fact that the conditions required for Liouville’s theorem to be valid are applicable to charged particle focusing but not to x-ray focusing. X-ray focusing (with currently available devices) causes an increase in electron beam “effective” emittance that would prevent even a fourth generation source, such as an ERL, from outperforming the existing CESR-X ring as a source of hard x-rays. As x-ray focusing devices are improved this will become less true and it will be important for CESR-X to keep pace. A plan for doing this is described.
 
 
THP163 Pre-Conceptual Design Requirements for an X-Ray Free Electron Laser for the MaRIE Experimental Facility at LANL electron, linac, site, FEL 2417
 
  • R.L. Sheffield, C.W. Barnes, M.A. Bourke, R.W. Garnett, M.S. Gulley, A.J. Taylor
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Work performed under the auspices of the U.S. Department of Energy, under contract DE-AC52-06NA25396.
The MaRIE (Matter-Radiation Interactions in Extremes) experimental facility will be used to advance materials science by providing the tools scientists need to develop materials that will perform predictably and on demand for currently unattainable lifetimes in extreme environments. The MaRIE facilities, the Multi-Probe Diagnostic Hall (MPDH), the Fission and Fusion Materials Facility (F3), and the Making, Measuring, and Modeling Materials (M4) Facility will each have experimental needs for one or more high-energy X-ray beam probes. MPDH will also require access to an electron beam probe. These probe beams can be created using a 20-GeV electron linac, both to serve as a source of electrons and as a driver for a set of up to five X-ray undulators for the high-energy X-rays. Because of space considerations at the facility, a high-gradient design is being investigated that will use a normal-conducting linac and X-band RF systems. Experimental requirements are also calling for relatively long pulse lengths, as well as interleaving high- and low-charge electron bunches. This paper will provide an overview of how an XFEL would address the scientific requirements for MaRIE.
 
 
THP168 FEL Beam Stability in the LCLS* FEL, electron, undulator, linac 2423
 
  • J.L. Turner, R. Akre, A. Brachmann, F.-J. Decker, Y.T. Ding, P. Emma, Y. Feng, A.S. Fisher, J.C. Frisch, A. Gilevich, P. Hering, K. Horovitz, Z. Huang, R.H. Iverson, D. Kharakh, A. Krasnykh, J. Krzywinski, H. Loos, M. Messerschmidt, S.P. Moeller, H.-D. Nuhn, D.F. Ratner, T.J. Smith, J.J. Welch, J. Wu
    SLAC, Menlo Park, California, USA
 
  Funding: *This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515
During commissioning and operation of the Linac Coherent Light Source (LCLS) x-ray Free Electron Laser (FEL) at the SLAC National Accelerator Center electron and x-ray beam size, shape, centroid motion have been studied. The studies, sources, and remediation are summarized in this paper.
 
 
THP181 Low Intensity Nonlinear Effects in Compton Scattering Sources electron, laser, scattering, radiation 2453
 
  • F. Albert, S.G. Anderson, C.P.J. Barty, M. Betts, R.R. Cross, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh, M. J. Messerly, C. Siders, S.S.Q. Wu
    LLNL, Livermore, California, USA
 
  The design and optimization of a Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering source are presented. A new precision source with up to 2.5 MeV photon energies, enabled by state of the art laser and x-band linac technologies, is currently being built at LLNL. Various aspects of the theoretical design, including dose and brightness optimization, will be presented. In particular, while it is known that nonlinear effects occur in such light sources when the laser normalized potential is close to unity, we show that these can appear at lower values of the potential. A three dimensional analytical model and numerical benchmarks have been developed to model the source characteristics, including nonlinear spectra. Since MEGa-ray sources are being developed for precision applications such as nuclear resonance fluorescence, assessing spectral broadening mechanisms is essential.
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
 
 
THP182 Overview of Current Progress on the LLNL Nuclear Photonics Facility and Mono-energetic Gamma-ray Source laser, electron, gun, scattering 2456
 
  • F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, D.P. McNabb, M. J. Messerly, C. Siders
    LLNL, Livermore, California, USA
  • C. Adolphsen, T.S. Chu, E.N. Jongewaard, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang
    SLAC, Menlo Park, California, USA
 
  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 new class of gamma-ray light source based on Compton scattering is made possible by recent progress in accelerator physics and laser technology. Mono-energetic gamma-rays are produced from collisions between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linear accelerator designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA 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 conduct nuclear resonance fluorescence experiments and address a broad range of current and emerging applications in nuclear photoscience. Users include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented, along with important applications.
 
 
THP199 Raising Photoemission Efficiency with Surface Acoustic Waves electron, laser, linac, lattice 2492
 
  • A. Afanasev
    Hampton University, Hampton, Virginia, USA
  • R.P. Johnson
    Muons, Inc, Batavia, USA
 
  Funding: Supported in part by Muons, Inc.
Current and future synchrotron radiation light sources and free electron laser facilities are in need of improvements in Electron Gun Technology, especially regarding the cost and efficiency of photoinjectors. The generation of Surface Acoustic Waves (SAW) on piezoelectric substrates is known to produce strong piezoelectric fields that propagate on the surface of the material. These fields significantly reduce the recombination probability of electrons and holes which can result in enhanced quantum efficiency of photoemission. Additional advantages are provided by the mobility of charge carriers that can be controlled by SAW. It is expected that this novel feature will result in enhanced efficiency of photocathode operation, leading to the production of intense, low emittance electron bunches at a high repetition rate using laser excitation.
 
 
THP202 First Operation of the LANL/AES Normal Conducting Radio Frequency Photoinjector cavity, vacuum, pick-up, cathode 2498
 
  • N.A. Moody, H.L. Andrews, G.O. Bolme, L.J. Castellano, C.E. Heath, F.L. Krawczyk, S. Kwon, D. C. Lizon, P.S. Marroquin, F.A. Martinez, D.C. Nguyen, M.S. Prokop, R.M. Renneke, W. Roybal, P.A. Torrez, W.M. Tuzel, T. Zaugg
    LANL, Los Alamos, New Mexico, USA
  • L. Roybal
    TechSource, Santa Fe, New Mexico, USA
 
  Funding: We gratefully acknowledge funding from the Office of Naval Research (ONR) and the High Energy Laser Joint Technology Office (HEL-JTO).
The LANL/AES normal-conducting radio-frequency (NCRF) injector has undergone high power testing, confirming field gradients of up to 10 MV/m at the cathode. Most NCRF designs are limited to low-duty-factor operation to constrain rf power consumption and limit ohmic heat generation. This cavity structure utilizes high density micro-channel cooling to successfully remove heat with the option of dynamic temperature control to actively adjust cavity resonance. This first high power rf test demonstrated stable cw (100% duty cycle) operation using resonant frequency tracking and produced intentional dark current emission from a roughened cathode blank. Resulting end-point x-ray measurements confirm the cathode gradient of 9.8 ± 0.2 MV/m required for acceleration of nC bunches to a beam energy of 2.5 MeV.
 
 
THP223 Laser Systems for Livermore's Mono-Energetic Gamma-Ray Source laser, electron, scattering, emittance 2540
 
  • D.J. Gibson, F. Albert, C.P.J. Barty, A.J. Bayramian, C.A. Ebbers, F.V. Hartemann, R.A. Marsh, M. J. Messerly
    LLNL, Livermore, California, USA
 
  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 Mono-energetic Gamma-Ray (MEGa-Ray) source, based on Compton scattering of a high-intensity laser beam off a highly relativistic electron beam, requires highly specialized laser systems. To minimize the bandwidth of the gamma-ray beam, the scattering laser must have minimal bandwidth, but also match the electron beam depth of focus in length. This requires a ~1 J, 10 ps, fourier-transform-limited laser system. Also required is a high-brightness electron beam, best provided by a photoinjector. This electron source in turn requires a second laser system with stringent requirements on the beam including flat transverse and longitudinal profiles and fast rise times. Furthermore, these systems must be synchronized to each other with ps-scale accuracy. Using a novel hyper-dispersion compressor configuration, advanced fiber amplifiers, and diode-pumped Nd:YAG amplifiers, we have designed laser systems that meet these challenges for the x-band photoinjector and Compton-scattering source being built at Lawrence Livermore National Laboratory.
 
 
FROCB2 Science with Light and Neutron Sources neutron, scattering, synchrotron, electron 2596
 
  • S.K. Sinha
    UCSD, La Jolla, California, USA
 
  In recent years there has been great progress in the development of accelerator-based light and neutron sources. The speaker will give an overview of the exciting new opportunities provided by the enhanced source capabilities available at present and future facilities.
Speaker Sunhil Sinha, a professor in the Physics Department of the University of California at San Diego
 
slides icon Slides FROCB2 [26.588 MB]