Keyword: polarization
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MOPWA013 Modeling and Measurements of Spin Depolarization kicker, electron, resonance, synchrotron 109
 
  • N. Carmignani, F. Ewald, L. Farvacque, B. Nash, P. Raimondi
    ESRF, Grenoble, France
  
  An electron bunch in a storage ring becomes spin polarized due to the Sokolov-Ternov effect. The beam may then be depolarized by applying a horizontal magnetic field oscillating in resonance with the spin tune. This technique has been used to measure the electron energy at numerous synchrotrons. In this paper, we report on modeling and measurements of the polarization and depolarization process at the ESRF. We report the results of a Matlab based parallelized spin tracking code that we developed for these studies. We show the change in depolarization resulting as different physical effects are added to the model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA013  
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MOPJE073 The Extreme Beams Initiative in EuCARD-2 collider, linac, hadron, diagnostics 483
 
  • G. Franchetti, J. Struckmeier
    GSI, Darmstadt, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  EuCARD-2 is an Integration Activity on accelerator R&D co-funded within the European Union’s 7th Framework Programme. The Extreme Beams (XBEAM) network of EuCARD-2 extends, and goes beyond the scope of, the previous Networking Activities of CARE-HHH and EuCARD(-1) EuroLumi. XBEAM addresses, and pushes, all accelerator frontiers: luminosity, energy, beam power, beam intensity, and polarization. This is realized through five tasks: Coordination and Communication, Extreme Colliders (XCOL)m Extreme Performance Rings (XRING), Extreme SC Linacs (XLINAC), and Extreme Polarization (XPOL), respectively. In the first two years of EuCARD-2, XBEAM (co-)organised more than 15 topical workshops: the upgrade of  KEKB in Japan, crystal channelling, the advancement of the CERN facilities, e.g. LHC upgrades and the Future Circular Collider, magnet optimization, space-charge effects, the commissioning of proton linacs, with emphasis on the ESS, key questions for lepton spin polarization, storage rings for measuring the electric dipole moment of electrons or protons. This presentation reports the major achievements of the XBEAM activity from 2013 to 2015, and outlines the further plans through 2017.   
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE073  
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MOPHA015 Measurement of Momentum Compaction Factor via Depolarizing Resonances at ELSA resonance, electron, extraction, experiment 811
 
  • J.F. Schmidt, W. Hillert, M. Schedler, J.-P. Thiry
    ELSA, Bonn, Germany
  
  Funding: DFG
Measuring beam depolarization at energies in close proximity to a depolarizing integer resonance is an established method to determine the beam energy of a circular accelerator. This technique offers high accuracy due to the small resonance widths. Thus, also other accelerator parameters related to beam energy can be measured based on this method. This contribution presents a measurement of the momentum compaction factor with a high precision of 10-4. It was performed at the 164 m stretcher ring of the Electron Stretcher Facility ELSA at Bonn University, which provides a polarized electron beam of up to 3.2 GeV. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA015  
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MOPHA024 A Novel Transverse Deflecting Cavity for Slice Diagnostics at BERLinPro cavity, SRF, emittance, low-level-rf 827
 
  • A. Ferrarotto, B. Riemann, T. Weis
    DELTA, Dortmund, Germany
  • H.-W. Glock, T. Kamps, J. Völker
    HZB, Berlin, Germany
  
  Funding: Work supported by BMBF under contract no. 05K10PEA
BERLinPro is an energy-recovery linac project to be realized at the Helmholtz-Zentrum Berlin (HZB) for an electron beam with 1mm mrad normalized emittance and 100 mA average current. The initial beam parameters are determined by the performance of the electron source, an SRF photo-electron injector. The development auf this SRF photon-electron injector is a main task of BERLinPro. Especially the beam emittance is basically defined by the SRF photogun. For beam diagnostics time dependent effects from the RF curvature and space charge must be taken into account and a sophisticated slice diagnostics is required. To perform this type of diagnostics a transverse deflecting cavity has been designed, characterized and is presently under construction.. This single cell cavity operates in a TM110-like mode at 1.3 GHz optimized for high transverse shuntimpedance of appr. 3.2 MOhm by a concentration of fields near the beam axis. The cavity has a novel geometry that allows for an operation with both polarizations of the TM110-Mode. The layout of the deflecting cavity will be presented together with the results of the low RF characterization. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA024  
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MOPTY011 Operation Experience of p-Carbon Polarimeter in RHIC target, detector, vacuum, operation 956
 
  • H. Huang, E.C. Aschenauer, G. Atoian, A. Bazilevsky, O. Eyser, D. Kalinkin, J. Kewisch, Y. Makdisi, S. Nemesure, A. Poblaguev, W.B. Schmidke, D. Smirnov, D. Steski, K. Yip, A. Zelenski
    BNL, Upton, Long Island, New York, USA
  • I.G. Alekseev, D. Svirida
    ITEP, Moscow, Russia
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The spin physics program in Relativistic Heavy Ion Collider (RHIC) requires fast polarimeter to monitor the polarization evolution on the ramp and during stores. Over past decade, the polarimeter has evolved greatly to improve its performance. These include dual chamber design, monitoring camera, Si detector selection (and orientation), target quality control, and target frame modification. The preamp boards have been modified to deal with the high rate problem, too. The ultra thin carbon target lifetime is a concern. Simulations have been carried out on the target interaction with beam. Modification has also been done on the frame design. Extra caution has been put on RF shielding to deal with the pickup noises from the nearby stochastic cooling kickers. This paper summarizes the recent operation performance of this delicate device. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY011  
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MOPWI035 Characterization of Visible Synchrotron Radiation Polarization at SPEAR3 radiation, synchrotron, synchrotron-radiation, diagnostics 1240
 
  • W.J. Corbett, A.M. Kiss
    SLAC, Menlo Park, California, USA
  • M.J. Boland
    The University of Melbourne, Melbourne, Victoria, Australia
  • C.L. Li
    East China University of Science and Technology, Shanghai, People's Republic of China
  
  Schwinger's equations predict the angular- and spectral distribution of synchrotron radiation across a wide band of the electromagnetic spectrum. Using a visible-light diagnostic beam line, it is possible to characterize the electric field polarization state as a function of vertical observation angle and compare with theory. Complications include accounting for - and π-mode transmission factors at mirror surfaces and precise alignment of the polarizing optics with the principle beam axes. The Stokes parameters are measured and beam polarization ellipse reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI035  
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TUYB3 Progress on the Design of the Polarized Medium-energy Electron Ion Collider at JLab ion, electron, collider, luminosity 1302
 
  • F. Lin, S.A. Bogacz, P.D. Brindza, A. Camsonne, E. Daly, Y.S. Derbenev, D. Douglas, R. Ent, D. Gaskell, R.L. Geng, J.M. Grames, J. Guo, L. Harwood, A. Hutton, K. Jordan, A.J. Kimber, G.A. Krafft, R. Li, T.J. Michalski, V.S. Morozov, P. Nadel-Turonski, F.C. Pilat, M. Poelker, R.A. Rimmer, Y. Roblin, T. Satogata, M. Spata, R. Suleiman, A.V. Sy, C. Tennant, H. Wang, S. Wang, H. Zhang, Y. Zhang, Z.W. Zhao
    JLab, Newport News, Virginia, USA
  • S. Abeyratne, B. Erdelyi
    Northern Illinois University, DeKalb, Illinois, USA
  • D.P. Barber
    DESY, Hamburg, Germany
  • Y. Cai, Y. Nosochkov, M.K. Sullivan, M.-H. Wang, U. Wienands
    SLAC, Menlo Park, California, USA
  • A. Castilla, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • Y. Filatov
    JINR, Dubna, Russia
  • J. Gerity, T.L. Mann, P.M. McIntyre, N. Pogue, A. Sattarov
    Texas A&M University, College Station, Texas, USA
  • C. Hyde, K. Park
    Old Dominion University, Norfolk, Virginia, USA
  • A.M. Kondratenko, M.A. Kondratenko
    Science and Technique Laboratory Zaryad, Novosibirsk, Russia
  • P.N. Ostroumov
    ANL, Argonne, Illinois, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The Medium-energy Electron Ion Collider (MEIC) at JLab is designed to provide high luminosity and high polarization needed to reach new frontiers in the exploration of nuclear structure. The luminosity, exceeding 1033 cm-2s−1 in a broad range of the center-of-mass (CM) energy and maximum luminosity above 1034 cm-2s−1, is achieved by high-rate collisions of short small-emittance low-charge bunches made possible by high-energy electron cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, 3He) can be easily preserved and manipulated due to the unique figure-8 shape of the collider rings. A fully consistent set of parameters have been developed considering the balance of machine performance, required technical development and cost. This paper reports recent progress on the MEIC accelerator design including electron and ion complexes, integrated interaction region design, figure-8-ring-based electron and ion polarization schemes, RF/SRF systems and ERL-based high-energy electron cooling. Luminosity performance is also presented for the MEIC baseline design. 		 
slides icon Slides TUYB3 [6.245 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUYB3  
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TUPWA026 Simulation of Optical Transport Beamlines for High-quality Optical Beams for Accelerator Applications laser, electron, simulation, FEL 1462
 
  • J. Bödewadt, N. Ekanayake
    DESY, Hamburg, Germany
  
  High-quality optical beams play already an important role in the field of particle accelerators which will most probably become even more prominent in the view of laser-driven particle accelerators. Nowadays, optical transport systems are needed for particle generation in photo injectors, for particle acceleration in laser-driven plasma wakefield accelerators, for particle beam diagnostics such as synchrotron radiation monitoring systems, or for particle manipulation schemes e.g. for external seeding of free-electron lasers. For the latter case, also the photon beam transport to the user end-stations requires dedicated optical transport system. The utilized wavelengths range from the hard x-ray up to the far-infrared spectral range. Parameters like surface quality, polarization effects, damage thresholds in- and out-of-vacuum, mechanical stability, dispersion effect etc. need to be studied for the variaty of applications. Here, we present the simulation results of the optical transport beamline for the seeding setup at FLASH and give a comparision to our measurement results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA026  
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TUPWA059 Modeling of Photoemission and Electron Spin Polarization from NEA GaAs Photocathodes electron, scattering, simulation, photon 1556
 
  • O. Chubenko, A. Afanasev
    GWU, Washington, USA
  
  Funding: Work supported by The George Washington University and Thomas Jefferson National Accelerator Facility.
Many nuclear-physics and particle-physics scientific laboratories, including Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (Jefferson Lab) which studies parity violation and nucleon spin structure, require polarized electron sources. At present, photoemission from strained GaAs activated to negative electron affinity (NEA) is a main source of polarized electrons. Future experiments at advanced electron colliders will require highly efficient polarized electron beams, which sets new requirements for photocathodes in terms of high quantum efficiency (QE) (>>1%) and spin polarization (~85%). Development of such materials includes modeling and design of photocathodes, material growth, fabrication of photocathodes, and photocathode testing. The purpose of the present work is to develop a semi-phenomenological model, which could predict photoemission and electron spin polarization from NEA GaAs photocathodes. Detailed Monte Carlo simulation and modeling of physical processes in photocathodes is important for optimization of their design in order to achieve high QE and reduce depolarization mechanisms. Electron-phonon interactions near the surface and influence of the presence of quantum heterostructures on the diffusion length are studied in depth. Simulation results will be compared to the experimental results obtained at Jefferson Lab and can be used to optimize the photocathode design and material growth, and thus develop high-polarization high-brightness electron source. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA059  
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TUPWA061 Analyses of Light's Orbital Angular Momentum from Helical Undulator Harmonics radiation, undulator, photon, emittance 1563
 
  • S. Sasaki, A. Miyamoto
    HSRC, Higashi-Hiroshima, Japan
  • M. Hosaka, N. Yamamoto
    Nagoya University, Nagoya, Japan
  • M. Katoh, T. Konomi
    UVSOR, Okazaki, Japan
  
  Funding: Partially supported by the Grant-in-Aid for Scientific Research, Japan Society for the Promotion of Science, and supported by the Joint Studies Program of the Institute for Molecular Science.
The phenomenon of higher harmonic radiation from a helical undulator carrying orbital angular momentum (OAM)* attracts a great deal of attention because this novel property may be used as a new probe for synchrotron radiation science** that would be performed in a diffraction limited light source facility such as the APS-II. Although a diffraction limited x-ray source does not yet exist, the 750 MeV UVSOR-III is already a diffraction limited light source in the UV region. In this ring, a tandem-aligned double-APPLE undulator system similar to that in BESSY-II*** is installed for FEL and coherent light source experiments. Using this set-up, we observed spiral interference patterns between two different harmonic radiations with a scanning fiber multi-channel spectrometer and a CCD camera placed at the end of BL1U Beamline. By these measurements, various interference patterns such as single, double, and triple spirals were observed which concur with the theoretical prediction for every mode in the right or left circular polarization. The rotation of an interference pattern by rotating a polarizer was also observed.
* S. Sasaki and I. McNulty, Phys. Rev. Lett. 100, 124801, 2008.
** M. VanVeenendaal and I. McNulty, Phys. Rev. Lett. 98, 157401 (2007).
*** J. Bahrdt, et al., Phys. Rev. Lett. 111, 034801, 2013. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA061  
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TUPWA070 CST Simulations of THz Cherenkov Smith-purcell Radiation from Corrugated Capillary radiation, simulation, electron, laser 1594
 
  • K. Lekomtsev, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • P. Karataev
    JAI, Egham, Surrey, United Kingdom
  • A. Ponomarenko, A.A. Tishchenko
    MEPhI, Moscow, Russia
  
  Recent advances in generation of femtosecond pre-bunched beams have a potential to generate coherent THz radiation occurring via combination of Smith-Purcell radiation (SPR) and Cherenkov radiation (ChR) generated in a corrugated capillary. This mechanism was studied theoretically *. LUCX accelerator at High Energy Accelerator Research Organisation (KEK) has been upgraded by introducing fs Ti:Sa laser system and it is currently generating short tens of fs electron bunches **. In this report we present EM simulations of Ch.SPR generated in a corrugated channel in infinite dielectric and in a dielectric corrugated capillary. CST PIC solver is used as a simulation tool. It was earlier used for simulation of Transition radiation ***. Intensity dependencies of ChR and SPR peaks as functions of the capillary radius and the corrugation depth are compared with the theoretical investigation *. Output of THz radiation from the dielectric capillary with a radiation reflector is simulated.
* A.A. Ponomarenko et. al, NIMB 309 (2013) 223-226.
** M. Fukuda et. al, NIMA 637 (2011) S67.
*** K.V. Lekomtsev et. al, J. Phys.: Conf. Ser. 517, (2014) 012016. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA070  
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TUPJE007 Measurement of Temporal Electric Field of Electron Bunch using Photoconductive Antenna electron, laser, linac, radiation 1623
 
  • K. Kan, M. Gohdo, T. Kondoh, I. Nozawa, A. Ogata, T. Toigawa, J. Yang, Y. Yoshida
    ISIR, Osaka, Japan
  
  A temporal electric field profile, which is a radially polarized terahertz (THz) pulse from an electron bunch, was measured by a large-aperture photoconductive antenna (PCA) with micro-structured concentric electrodes* for the detection of THz pulses. Photo-induced charge carriers were generated by irradiation of femtosecond laser pulses on semiconductor plane of the electrodes on the PCA. Time-domain measurement of coherent transition radiation (CTR) was conducted by the measurement of electric-field-induced current output from the PCA with sweeping the timing of the laser irradiation. The measurements on femtosecond electron bunches of 32 MeV and >80 pC will be reported.
* K. Kan et al., Appl. Phys. Lett. 102, 221118 (2013). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE007  
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TUPJE022 Study on Beam Dynamics of a Knot-APPLE Undulator Proposed for SSRF undulator, sextupole, quadrupole, operation 1669
 
  • Q.L. Zhang, B.C. Jiang, S.Q. Tian, Z.T. Zhao, Q.G. Zhou
    SINAP, Shanghai, People's Republic of China
  
  A new type of undulator, Knot-APPLE undulator, is proposed for SSRF as a solution to reduce the heat load of on-axis high harmonics without losing its capability of tuning synchrotron polarization. It will be applied for SSRF Photoemission Spectroscopy beamline (PES-beamline) in the near future. Impact of the undulator on the beam dynamics has been studied based on the 3D magnetic field model and kick map analysis. Linear optics can be retained by quadrupole compensation within two adjacent cells. Dynamical aperture (DA) shrinkage has been found in the tracking and optimized with sextupoles. An active correction scheme of current strips is studied to compensate the kick maps, and both the linear and nonlinear effects are suppressed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE022  
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TUPMA020 PEPPo: Using a Polarized Electron Beam to Produce Polarized Positrons positron, electron, target, solenoid 1878
 
  • A.H. Adeyemi, P.L. Gueye
    Hampton University, Hampton, Virginia, USA
  • P.A. Adderley, M.M. Ali, H. Areti, J. F. Benesch, L.S. Cardman, J. Clark, S. Covert, C. Cuevas, A. Freyberger, S. Golge, J.M. Grames, P.L. Gueye, J. Hansknecht, P.L. Harrell, C. Hyde, R. Kazimi, Y. Kim, D. Machie, K.L. Mahoney, R.R. Mammei, J.L. McCarter, M.D. McCaughan, M. Poelker, M.L. Stutzman, R. Suleiman, C.-Y. Tsai, D.L. Turner, Y.W. Wang
    JLab, Newport News, Virginia, USA
  • M.A. Baylac, E. Froidefond, M. Marton, J-F. Muraz, J-S. Real, E. J-M. Voutier
    LPSC, Grenoble Cedex, France
  • P. Cole, D. Dale, T.A. Forest
    ISU, Pocatello, Idaho, USA
  • O. Dadoun, A. Variola
    LAL, Orsay, France
  • D. Dale, Y. Kim
    IAC, Pocatello, Idaho, USA
  • EF. Fanchini
    INFN Genova, Genova, Italy
  • S. Golge
    NCCU, , North Carolina, USA
  • S. Golge, C. Hyde
    ODU, Norfolk, Virginia, USA
  • J.L. McCarter
    UVa, Charlottesville, Virginia, USA
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  • A. Variola
    IN2P3-CNRS, Orsay, France
  
  Polarized positron beams have been identified as either an essential or a significant ingredient for the experimental program of both the present and next generation of lepton accelerators (JLab, Super KEK B, ILC, CLIC). An experiment demonstrating a new method for producing polarized positrons has been performed at the Continuous Electron Beam Accelerator Facility at Jefferson Lab. The PEPPo (Polarized Electrons for Polarized Positrons) concept relies on the production of polarized e−/e+ pairs from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a high Z conversion target. PEPPo demonstrated the effective transfer of spin-polarization of an 8.2 MeV/c polarized (P~85%) electron beam to positrons produced in varying thickness tungsten production targets, and collected and measured in the range of 3.1 to 6.2 MeV/c. In comparison to other methods this technique reveals a new pathway for producing either high energy or thermal polarized positron beams using a relatively low polarized electron beam energy (~10MeV) .This presentation will describe the PEPPo concept, the motivations of the experiment and high positron polarization achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA020  
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TUPMA038 Observation of Significant Quantum Efficiency Enhancement from a Polarized Photocathode with Distributed Brag Reflector laser, electron, cathode, vacuum 1923
 
  • S. Zhang, M. Poelker, M.L. Stutzman
    JLab, Newport News, Virginia, USA
  • Y. Chen, A. Moy
    SVT Associates, Eden Prairie, Minnesota, USA
  
  Funding: This project was supported by the U.S. DOE Basic Energy Sciences under contract No. DE-AC05-060R23177.
Polarized photocathodes with higher Quantum efficiency (QE) would help to reduce the technological challenge associated with producing polarized beams at milliampere levels, because less laser light would be required, which simplifies photocathode cooling requirements. And for a given amount of available laser power, higher QE would extend the photogun operating lifetime. The distributed Bragg reflector (DBR) concept was proposed to enhance the QE of strained-superlattice photocathodes by increasing the absorption of the incident photons using a Fabry-Perot cavity formed between the front surface of the photocathode and the substrate that includes a DBR, without compromising electron polarization. Here we present recent results showing QE enhancement of a GaAs/GaAsP strained-superlattice photocathode made with a DBR structure. Typically, a GaAs/GaAsP strained-superlattice photocathode without DBR provides a QE of 1%, at a laser wavelength corresponding to peak polarization. In comparison, the GaAs/GaAsP strained-superlattice photocathodes with DBR exhibited an enhancement of over 2 when the incident laser wavelength was tuned to meet the resonant condition for the Fabry-Perot resonator. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA038  
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TUPTY017 Ion Polarization Control in the MPD and SPD Detectors of the NICA Collider solenoid, collider, detector, proton 2031
 
  • A.D. Kovalenko, A.V. Butenko, V.D. Kekelidze, V.A. Mikhaylov
    JINR, Dubna, Moscow Region, Russia
  • Y. Filatov
    MIPT, Dolgoprudniy, Moscow Region, Russia
  • A.M. Kondratenko, M.A. Kondratenko
    Science and Technique Laboratory Zaryad, Novosibirsk, Russia
  
  Two solenoid Siberian snakes are placed in the opposite collider’s straight sections are used to control deuteron’s and proton’s polarization in the NICA collider. Solenoid snakes substantially reconstruct beam’s orbital motion. The change of the polarization direction in the vertical plane of MPD and SPD detectors occurs due to insertion of polarization control (PC) solenoids in the magnetic lattice of the collider. The solenoids rotating particle’s spin by small angels practically do not influence on the beam’s orbital motion parameters. The dynamic of the polarization vector as function of the orbit length for cases of longitudinal and vertical polarization in the MPD and SPD detectors are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY017  
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TUPTY063 FCC-ee: Energy Calibration wiggler, storage-ring, electron, simulation 2177
 
  • M. Koratzinos, A.P. Blondel
    DPNC, Genève, Switzerland
  • E. Gianfelice-Wendt
    Fermilab, Batavia, Illinois, USA
  • F. Zimmermann
    CERN, Geneva, Switzerland
  
  FCC-ee aims to improve on electroweak precision measurements, with goals of 100 keV on the Z mass and width, and a fraction of an MeV on the W mass. Compared to LEP, this implies a much improved knowledge of the centre-of-mass energy when operating at the Z peak and WW threshold. This contribution will describe how it is planned to achieve this, by making systematic use of resonant depolarization. A number of difficulties have been identified, due in particular to the long polarization time and amplified ground motion. However the smaller emittance and energy spread of FCC-ee with respect to LEP should help achieve a much improved performance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY063  
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TUPWI010 Development of a Pulse Radiolysis System by Ultra-fast Super Continuum Probe at Waseda University laser, gun, electron, cathode 2265
 
  • Y. Ito
    Waseda University, Tokyo, Japan
  • Y. Hosaka, K. Sakaue, M. Washio
    RISE, Tokyo, Japan
  
  We have been studying the pulse radiolysis using photo-cathode rf gun at Waseda Univ. Pulse radiolysis is one of the powerful methods to trace early chemical reactions by ionizing radiation. In pulse radiolysis, the probe light absorption, which produced by active species formed by electron beam of rf gun, is measured at each wavelength and made possible to trace reactions. Therefore, we have used the super continuum (SC) light for the probe light. The SC light has a broad spectrum and is generated by nonlinear optical effect caused by injecting picosecond laser to photonic crystal fiber. However, the resulting SC light was unstable because its peak intensity was not enough. We need to use a femtosecond pulsed laser which is expected to be stronger peak intensity than a picosecond laser. We have developed a mode-locked Yb-doped fiber laser based on Non-Linear Polarization Rotation as a femtosecond pulsed laser and the chirped pulse amplification system which will be able to amplify the femtosecond pulse. In this conference, we will report the performance of the SC light using this fiber laser system, recent results of pulse radiolysis experiments and the future plans.
Work supported by NEDO(New Energy and Industrial Technology Development Organization). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI010  
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TUPWI029 Baseline Scheme for Polarization Preservation and Control in the MEIC Ion Complex ion, collider, controls, solenoid 2301
 
  • V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
    JLab, Newport News, Virginia, USA
  • Y. Filatov
    MIPT, Dolgoprudniy, Moscow Region, Russia
  • A.M. Kondratenko, M.A. Kondratenko
    Science and Technique Laboratory Zaryad, Novosibirsk, Russia
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The scheme for preservation and control of the ion polarization in the Medium-energy Electron-Ion Collider (MEIC) has been under active development in recent years. The figure-8 configuration of the ion rings provides a unique capability to control the polarization of any ion species including deuterons by means of "weak" solenoids rotating the particle spins by small angles. Insertion of "weak" solenoids into the magnetic lattices of the booster and collider rings solves the problem of polarization preservation during acceleration of the ion beam. Universal 3D spin rotators designed on the basis of "weak" solenoids allow one to obtain any polarization orientation at an interaction point of MEIC. This paper presents the baseline scheme for polarization preservation and control in the MEIC ion complex. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI029  
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TUPWI030 Numerical Calculation of the Ion Polarization in MEIC collider, controls, solenoid, proton 2304
 
  • V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
    JLab, Newport News, Virginia, USA
  • Y. Filatov
    MIPT, Dolgoprudniy, Moscow Region, Russia
  • A.M. Kondratenko, M.A. Kondratenko
    Science and Technique Laboratory Zaryad, Novosibirsk, Russia
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
Ion polarization in the Medium-energy Electron-Ion Collider (MEIC) is controlled by means of universal 3D spin rotators designed on the basis of “weak” solenoids. We use numerical calculations to demonstrate that the 3D rotators have negligible effect on the orbital properties of the ring. We present calculations of the polarization dynamics along the collider’s orbit for both longitudinal and transverse polarization directions at a beam interaction point. We calculate the degree of depolarization due to the longitudinal and transverse beam emittances in case when the zero-integer spin resonance is compensated. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI030  
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TUPWI049 Polarized Proton Beam for eRHIC emittance, resonance, proton, booster 2360
 
  • H. Huang, F. Méot, V. Ptitsyn, T. Roser
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
RHIC has provided polarized proton collisions from 31 GeV to 255 GeV in past decade. To preserve polarization through numerous depolarizing resonances through the whole accelerator chain, harmonic orbit correction, partial snakes, horizontal tune jump system and full snakes have been used. In addition, close attentions have been paid to betatron tune control, orbit control and beam line alignment. The polarization of 60% at 255 GeV has been delivered to experiments with 1.8×1011 bunch intensity. For the eRHIC era, the beam brightness has to be maintained to reach the desired luminosity. Since we only have one hadron ring in the eRHIC era, existing spin rotator and snakes can be converted to six snake configuration for one hadron ring. With properly arranged six snakes, the polarization can be maintained at 70% at 250 GeV. This paper summarizes the effort and plan to reach high polarization with small emittance for eRHIC. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI049  
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TUPWI052 End-to-end 9-D+SR Polarized Bunch Transport in eRHIC Energy-recovery Recirculator, Some Aspects emittance, electron, quadrupole, linac 2369
 
  • F. Méot, S.J. Brooks, V. Ptitsyn, D. Trbojevic, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The energy-recovery electron beam recirculator, part of the eRHIC electron-ion collider project complex at BNL, is subject to feasibility studies in an FFAG arc based version. We develop here on tracking simulations and their analysis, regarding end-to-end polarized e-bunch transport in presence of synchrotron radiation, magnet alignment and field errors. Simulations include the evolution of energy, orbits, emittances, polarization profiles. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI052  
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TUPWI053 Polarization Simulations in the RHIC Run 15 Lattice resonance, optics, simulation, lattice 2372
 
  • F. Méot, H. Huang, Y. Luo, V.H. Ranjbar, G. Robert-Demolaize
    BNL, Upton, Long Island, New York, USA
  • S.M. White
    ESRF, Grenoble, France
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
RHIC polarized proton Run 15 uses a new acceleration ramp optics, compared to RHIC Run~14 and earlier runs, in relation with electron-lens beam-beam compensation developments. The new optics induces different strengths in the depolarizing snake resonance sequence, from injection to top energy. As a consequence, polarization transport along the new ramp has been investigated, based on spin tracking simulations. Sample results are reported and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI053  
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TUPWI054 9-D Polarized Proton Transport in the MEIC "Figure-8" Collider Ring - First Steps dipole, lattice, quadrupole, collider 2375
 
  • F. Méot
    BNL, Upton, Long Island, New York, USA
  • V.S. Morozov
    JLab, Newport News, Virginia, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Spin tracking studies in the MEIC figure-8 collider ion ring are presented, based on a preliminary design of the lattice. They provide numerical illustrations of some of the aspects of the figure-8 concept, including spin-rotator based spin control, and lay out the path towards complete spin tracking simulations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI054  
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TUPWI060 RHIC Polarized Proton-Proton Operation at 100 GeV in Run 15 proton, electron, emittance, operation 2384
 
  • V. Schoefer, E.C. Aschenauer, G. Atoian, M. Blaskiewicz, K.A. Brown, D. Bruno, R. Connolly, T. D'Ottavio, K.A. Drees, Y. Dutheil, W. Fischer, C.J. Gardner, X. Gu, T. Hayes, H. Huang, J.S. Laster, C. Liu, Y. Luo, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, S. Nemesure, P.H. Pile, A. Poblaguev, V.H. Ranjbar, G. Robert-Demolaize, T. Roser, W.B. Schmidke, F. Severino, T.C. Shrey, K.S. Smith, D. Steski, S. Tepikian, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, S.M. White, K. Yip, A. Zaltsman, A. Zelenski, K. Zeno, S.Y. Zhang
    BNL, Upton, Long Island, New York, USA
  
  The first part of RHIC Run 15 consisted of nine weeks of polarized proton on proton collisions at a beam energy of 100 GeV at two interaction points. In this paper we discuss several of the upgrades to the collider complex that allowed for improved performance this run. The largest effort consisted of commissioning of the electron lenses, one in each ring, which are designed to compensate one of the two beam-beam interactions experienced by the proton bunches. The e-lenses therefore raise the per bunch intensity at which luminosity becomes beam-beam limited. A new lattice was designed to create the phase advances necessary for a functioning e-lens which also has an improved off-momentum dynamic aperture relative to previous runs. In order to take advantage of the new, higher intensity limit without suffering intensity driven emittance deterioration, other features were commissioned including a continuous transverse bunch-by-bunch damper in RHIC and a double harmonic capture scheme in the Booster. Other high intensity protections include improvements to the abort system and the installation of masks to intercept beam lost due to abort kicker pre-fires.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI060  
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WEAD3 Quantum Efficiency Improvement of Polarized Electron Source using Strain Compensated Super Lattice Photocathode electron, laser, gun, collider 2479
 
  • N. Yamamoto, M. Hosaka, A. Mano, T. Miyauchi, Y. Takashima, Y. Takeda
    Nagoya University, Nagoya, Japan
  • X.J. Jin, M. Yamamoto
    KEK, Ibaraki, Japan
  
  Polarized electron beam is essential for future electron-positron colliders and electron-ion colliders. Improving the quantum efficiency is an important subject to realize those proposed applications. Recently we have developed the strain compensated superlattice (SL) photocathode. In the strain compensated SLs, the equivalent compressive and tensile strains introduced in the well and barrier SL layers so that strain relaxation is effectively suppressed with increasing the SL layer thickness and high crystal quality can be expected. In this study, we fabricated the GaAs/GaAsP strain compensated SLs with the thickness up to 90-pair SL layers. Up to now, the electron spin polarization of 92 % and the quantum efficiency of 1.6 % were simultaneously achieved from 24-pair sample. In the presentation, we show the effect of the superlattice thickness on the photocathode performances and discuss the photocathode physics.  
slides icon Slides WEAD3 [3.064 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEAD3  
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WEPMA044 25 Hz, Sub-mJ Ytterbium Laser Source of RF Gun for SuperKEKB Linac laser, gun, cavity, electron 2862
 
  • X. Zhou, T. Natsui, Y. Ogawa, M. Yoshida, R. Zhang
    KEK, Ibaraki, Japan
  
  For injector linac of SuperKEKB project, the 5 nC electron beams with double-bunch is expected to be generated in the photocathode RF gun. For the repetition rate of electrum beam, the optional of 2 Hz, 5 Hz, 25 Hz and 50 Hz are requested. Although, more than 5 nC electron with single-bunch has been generated in the 2 Hz and 5 Hz, when the repetition rate increases to 25 Hz, the condition of the laser amplifier system such as the thermal lens effect is changed seriously. To correspond to 25 Hz repetition rate, the ytterbium-doped laser system was reformed. An AuSu (80:20) heat-dissipating solder is employed to reduce the thermal lens effect. Because of the damage threshold limitation of the thin-disk crystal and optical mirrors, Some improvement were performed to increase the quality of the pulses rather than the amplify power, which cause the SHG conversion efficiency is up to 60% and 30% with 2ω and 4ω respectively. More than 3 nC electron beam is obtained with 25 Hz.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA044  
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WEPHA025 Design of a Variable X-band RF Power Splitter network, impedance, operation, scattering 3167
 
  • H. Zha, A. Grudiev, D. Gudkov, I. Syratchev
    CERN, Geneva, Switzerland
  
  The design of a two output ports, high power X-Band RF splitter with arbitrary split ratio is presented. This ratio is adjusted by mechanical changing the position a special RF short circuit piston. The piston is mounted on a step-motor providing the precise movement. Special measures were taken in the design to decrease the maximum electrical field on the cooper surface, as well as to maximise the bandwidth of the device. This splitter will be tested in the high power X-band test stand at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA025  
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THPF031 Towards an RF Wien-Filter for EDM Experiments at COSY dipole, resonance, betatron, storage-ring 3761
 
  • S. Mey, R. Gebel
    FZJ, Jülich, Germany
  
  Funding: The work is supported within the framework of the Helmholtz Association’s Accelerator Research and Development (ARD) program.
The JEDI Collaboration (Jülich Electric Dipole Moment (EDM) Investigations) is developing tools for the measurement of permanent EDMs of charged, light hadrons in storage rings. The Standard Model predicts unobservably small values for the EDM, but a non-vanishing EDM can be detected by measuring a tiny build-up of vertical polarization in a beforehand horizontally polarized beam. This technique requires a spin tune modulation by an RF Dipole without any excitation of beam oscillations. In the course of 2014, a prototype RF ExB-Dipole has been successfully commissioned and tested. To determine the characteristics of the device, the force of a radial magnetic field is canceled out by a vertical electric one. In this configuration, the dipole fields form a Wien-Filter that directly rotates the particles' polarization vector. We verified that the device can be used to continuously flip the vertical polarization of a 970 MeV(c deuteron beam without exciting any coherent beam oscillations. For a first EDM Experiment, the RF ExB-Dipole in Wien-Filter Mode is going to be rotated by 90° around the beam axis and will be used for systematic investigations of sources for false EDM signals. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF031  
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THPF032 Spin Tracking Simulations Towards Electric Dipole Moment Measurements at COSY quadrupole, solenoid, resonance, distributed 3764
 
  • M. Rosenthal, A. Lehrach
    FZJ, Jülich, Germany
  • A. Lehrach, M. Rosenthal
    RWTH, Aachen, Germany
  
  A strong hint for physics beyond the Standard Model would be achieved by direct measurements of charged particles' Electric Dipole Moments (EDMs). Measurements in magnetic storage rings using a resonant spin interaction of a radiofrequency Wien filter are proposed and needs to be scrutinized. Therefore, the calculation of phase space transfer maps for time-varying fields has been implemented into an extensions for the software framework COSY INFINITY. Benchmarking with measured data and analytical estimates for rf solenoid induced spin resonances are in good agreement. The dependence of polarization oscillation damping on the solenoid frequency could be confirmed. First studies of the rf Wien filter method reveal systematic limitations: Uncorrected Gaussian distributed misalignments of the COSY lattice quadrupoles with a standard deviation of 0.1 mm generate a similar buildup as an EDM of 5·10-19 e cm using this method.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF032  
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THPF142 High Intensity Source of He Negative Ions ion, ion-source, target, electron 4057
 
  • V.G. Dudnikov
    Muons, Inc, Illinois, USA
  • A.V. Dudnikov
    BINP SB RAS, Novosibirsk, Russia
  • V.S. Morozov
    JLab, Newport News, Virginia, USA
  
  He- ion can be formed by an attachment of additional electron to the excited metastable 23S1 He atom. Electron affinity in this metastable He- ion is A=0.08 eV with excitation energy 19.8 eV. Production of He- ions is difficult because the formation probability is very small but destruction probability is very high. Efficiency of He- ions generation was improved by using of an alkali vapor targets for charge exchange He- sources. Low current He- beams were used in tandem accelerators for research and technological diagnostics (Rutherford scattering). The development of high-intensity high-brightness arc-discharge ion sources at the Budker Institute of Nuclear Physics (BINP) has opened up an opportunity for efficient production of more intense and more brighter He- beam which can be used for alpha particles diagnostics in a fusion plasma and for realization of a new type of a polarized 3He− ion source. This report discusses the high intense He- beams production and a polarized 3He− ion source based on the large difference of extra-electron auto-detachment lifetimes of the different 3He− ion hyperfine states.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF142  
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THPF146 Spin Coherence Time Lengthening of a Polarized Deuteron Beam Using Sextupole FieldsFields sextupole, storage-ring, emittance, electron 4066
 
  • G. Guidoboni
    UNIFE, Ferrara, Italy
  
  Funding: Forschungszentrum Jülich is a member of the Helmholtz Association
The measurement of a non-zero electric dipole moment (EDM) aligned along the spin of sub-atomic particles would probe new physics beyond the standard model. It has been proposed to search for the EDM of charged particles using a storage ring and a longitudinally polarized beam. The EDM signal would be a rotation of the polarization from the horizontal plane toward the vertical direction as a consequence of the radial electric field always present in the particle frame. This experiment requires ring conditions that can ensure a lifetime of the in-plane polarization (spin coherence time, SCT) up to 1000 s. At the COoler SYnchrotron (COSY) located at the Forschungszentrum Jülich, the JEDI collaboration has begun to examine the effects of emittance and momentum spread on the SCT of a polarized deuteron beam at 0.97 GeV/c. The set of data presented here shows how second-order effects from emittance and momentum spread of the beam affect the lifetime of the horizontal polarization of a bunched beam. It has been observed that sextupole fields can correct for depolarizing sources and increase the spin coherence time up to hundreds of seconds while setting the chromaticities equal to zero. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF146  
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