SUPLH —  Student Poster Session-Lake Huron   (01-Sep-19   14:00—16:00)
Paper Title Page
SUPLH01
Design of a 200 kV DC Cryocooled Photoemission Gun for Photocathode Investigations  
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  • G.S. Gevorkyan, S.S. Karkare
    Arizona State University, Tempe, USA
  • I.V. Bazarov, A. Galdi, J.M. Maxson
    Cornell University, Ithaca, New York, USA
  • L. Cultrera, W.H. Li
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was supported by the U.S. National Science Foundation under Award No. PHY-1549132, the Center for Bright Beams.
Intrinsic emittance of photocathodes limits the brightness of electrons beams produced from photoemission guns. Recent advancements have shown that an order of magnitude improvement in intrinsic emittance over the commonly used polycrystalline metal and semiconductor cathodes is possible via use of single crystalline ordered surfaces of metals, semiconductors and other exotic materials at cryogenic temperatures as cathodes. However, due to practical design considerations, it is not trivial to test such cathodes in existing electron guns. Here we present the design of a 200kV DC electron gun being developed at the Arizona State University for this purpose.
 
 
SUPLH03
Study of Fluctuations in Undulator Radiation in the IOTA Ring at Fermilab  
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  • I. Lobach
    University of Chicago, Chicago, Illinois, USA
  • A. Halavanau, Z. Huang, V. Yakimenko
    SLAC, Menlo Park, California, USA
  • K. Kim
    ANL, Lemont, Illinois, USA
  • V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari
    Fermilab, Batavia, Illinois, USA
  • A.Y. Murokh
    RadiaBeam, Marina del Rey, California, USA
  • T.V. Shaftan
    BNL, Upton, New York, USA
 
  We study turn-by-turn fluctuations in the number of emitted photons in an undulator, installed in the IOTA electron storage ring at Fermilab, with an InGaAs PIN photodiode and an integrating circuit. In this paper, we present a theoretical model for the experimental data from previous similar experiments and in our present experiment, we attempt to verify the model in an independent and a more systematic way. Moreover, in our experiment we consider the regime of very small fluctuation when the contribution from the photon shot noise is significant, whereas we believe it was negligible in the previous experiments. Accordingly, we present certain critical improvements in the experimental setup that let us measure such a small fluctuation.  
slides icon Slides SUPLH03 [8.044 MB]  
 
SUPLH04
Generation and Characterization of Attosecond Pulses From X-Ray Free-Electron Laser  
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  • S. Li
    SLAC, Menlo Park, California, USA
 
  In this talk I will discuss the production and application of sub-femtosecond x-ray pulses recently generated at LCLS. I will focus on angular streaking as the measurement technique to resolve the extremely short x-ray pulses. This method exploits phase dependent energy modulation of a photoelectron ionized in the presence of a strong laser field with circular polarization. I will present experimental results of single shot images and preliminary analysis results. Specifically I will discuss two applications of this technique: streaking of the Auger electrons and measuring the shape resonance directly in the time domain.  
slides icon Slides SUPLH04 [15.721 MB]  
 
SUPLH05
Thermal Effects on Bragg Diffraction of XFEL Optics  
TUPLH09   use link to access more material from this paper's primary paper code  
 
  • Z. Qu, J. Wu, G. Zhou
    SLAC, Menlo Park, California, USA
  • Y. Ma, Z. Qu
    UC Merced, Merced, California, USA
  • B. Yang
    Western Digital, Milpitas, California, USA
 
  Funding: The US Department of Energy (DOE) (DE-AC02-76SF00515); The US DOE Office of Science Early Career Research Program grant (FWP-2013-SLAC-100164).
Crystal optical devices are widely used in X-ray free electron laser (XFEL) systems, monochromators, beam splitters, high-reflectance backscattering mirrors, lenses, phase plates, diffraction gratings, and spectrometers. The absorption of X-ray in these optical devices can cause increase of temperature and consequent thermal deformation, which can dynamic change in optic output. In self-seeding XFEL, the thermal deformation and strain in monochromator could cause significant seed quality degradation: central energy shift, band broadening and reduction in seed power. To quantitatively estimate the impact of thermomechanical effects on seed quality, we conduct thermomechanical simulations combined with diffraction to evaluate the seed quality with residual temperature field in a pump-probe manner. With our results, we show that a critical repetition rate could be determined, once the criteria for deviation of the seed quality are selected. This tool shows great potential for the design of XFEL optics for stable operation.
 
 
SUPLH06
Design of the ASU Photocathode Lab  
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  • C.J. Knill, S.S. Karkare
    Arizona State University, Tempe, USA
  • J.V. Conway, B.M. Dunham, K.W. Smolenski
    Xelera Research LLC, Ithaca, New York, USA
  • H.A. Padmore
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
Recent investigations have shown that it is possible to obtain an order of magnitude smaller intrinsic emittance from photocathodes by precise atomic scale control of the surface, using an appropriate electronic band structure of single crystal cathodes and cryogenically cooling the cathode. Investigating the performance of such cathodes requires atomic scale surface diagnostic techniques connected in ultra-high vacuum (UHV) to the epitaxial thin film growth and surface preparation systems and photo-emission and photocathode diagnostic techniques. Here we report the capabilities and design of the laboratory being built at the Arizona State University for this purpose. The lab houses a 200 kV DC gun with a cryogenically cooled cathode along with a beam diagnostics and ultra fast electron diffraction beamline. The cathode of the gun can be transported in UHV to a suite of UHV growth chambers and surface and photoemission diagnostic techniques.
 
 
SUPLH07
Active Pointing Stabilization Techniques Applied to the Low Energy RHIC Electron Cooling Laser Transport at BNL  
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  • L.K. Nguyen, A.J. Curcio, W.J. Eisele, A.V. Fedotov, A. Fernando, W. Fischer, P. Inacker, J.P. Jamilkowski, D. Kayran, K. Kulmatycski, D. Lehn, T.A. Miller, M.G. Minty, A. Sukhanov
    BNL, Upton, 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 electron beam for the Low Energy RHIC electron Cooler (LEReC) at Brookhaven National Laboratory (BNL) is generated by a high-power fiber laser illuminating a photocathode. The pointing stability of the electron beam, which is crucial given its long transport, is highly dependent on the center-of-mass (CoM) stability of the laser spot on the photocathode. For reasons of accessibility during operations, the laser is located outside the accelerator tunnel, and the laser beam is propagated over a total distance of 34 m via three laser tables to the photocathode. The challenges to achieving the required CoM stability of 10 microns RMS on the photocathode include mitigation of the effects of vibrations along the transport and of weather- and season-related environmental effects, while preserving accessibility and diagnostic capabilities. Due to the insufficiency of infrastructure alone in overcoming these challenges, two active laser transport stabilization systems aimed at addressing specific types of position instability were installed during the 2018 Shutdown. After successful commissioning of the full transport in 2018/19, we report on our solutions to these design challenges.
 
slides icon Slides SUPLH07 [3.421 MB]  
 
SUPLH08
Spectroscopic Correlations to Resistive Switching of Ion Beam Irradiated Films  
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  • K.N. Rathod, N.A. Shah, P.S. Solanki
    Saurashtra University, Rajkot, India
  • K. Asokan
    IUAC, New Delhi, India
  • K.H. Chae, J.P. Singh
    Korea Institute of Science and Technology, Advanced Analysis Center, Seoul, Republic of Korea
 
  Researchers concentrated on resistive random access memories (RRAMs) due to excellent scalability, high integration density, quick switching, etc*,**. Intrinsic physical phenomenon of RRAMs is resistive switching. In this work, ion beam irradiation was used as a tool to modify resistive switching of pulsed laser deposited (PLD) Y0.95Ca0.05MnO3/Si films. Ion irradiation induced optimal resistive switching with spectroscopic correlations has been attributed to oxygen vacancy gradient. Resistive switching ratio is estimated to be increased for the film irradiated with fluence 1×1011 ions/cm2 due to irradiation induced strain and oxygen vacancies verified by X’ray diffraction (XRD), Raman, atomic force microscopy (AFM), Rutherford backscattering spectrometry (RBS) and near-edge X-ray absorption fine structure (NEXAFS) measurements. Strain relaxation and oxygen vacancy annihilation have been realized for higher fluence (1×1012 and 1×1013 ions/cm2) owing to local annealing effect. Present study suggests that the films understudy can be considered as emerging candidates for RRAMs.
* X.J. Zhu et al., Front. Mater. Sci. 6 (2012) 183, 206.
** D.S. Jeong et al., Rep. Prog. Phys. 75 (2012) 076502:1,31.
 
 
SUPLH09
The Possibility of L-Band Cavities for Medium-Beta Multi-Charge-State Heavy-Ion Beams and Cryomodule Conceptual Design Possible Options  
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  • S.M. Shanab
    FRIB, East Lansing, Michigan, USA
 
  Funding: This material is based upon work supported by the National Science Foundation NSF Cooperative Agreement PHY-1102511 and PHY-1565546
A simple analytic study was performed and beam dynamic simulations confirmed that result and showed that the 1288 MHz cavity is sufficient for medium-beta heavy ion accelerators. The result showed that the longitudinal acceptance of the L-band linac is sufficient for medium-beta heavy ion with 5 charge states beams. As a next step we studied possible options of efficient and compact L-band cryomodule conceptual designs for medium-beta heavy ion multi-charge-state linac. Two options were considered in this paper. First option is a cylindrical cross-section cryomodule design similar to International Linear Collider (ILC) cryomodule design and the second one is a rectangular cross-section cryomodule design similar to the Facility for Rare Isotope Beams (FRIB) cryomodule. This paper discusses these possible options in terms of size, shielding, alignments, and efficiency.
 
poster icon Poster SUPLH09 [3.505 MB]  
 
SUPLH10
Dual-Function Electron Ring-Ion Booster Design for JLEIC High-Energy Option  
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  • J.L. Martinez Marin, B. Mustapha
    ANL, Lemont, Illinois, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
As part of the alternative design approach for the Jeffer-son Laboratory Electron-Ion Collider (JLEIC) ion com-plex, the electron storage ring (e-ring) is consolidated to also serve as a large booster for the ions. The goal of reaching 16 GeV/u or higher for all ions using only room-temperature magnets forces the re-design of the e-ring because of magnetic field and lattice limitations. The new design is challenging due to several imposed constraints: (1) use of room-temperature magnets, (2) avoiding transi-tion crossing, and (3) maintaining the size and shape of the original e-ring design as much as possible. A design study is presented for a 16 GeV/u large ion booster after analyzing different alternatives that use: (1) combined-function magnets, (2) large quadrupoles or (3) quadrupole doublets in the lattice design. This design boosts the injection energy to the collider ring from 8 GeV (proton-equivalent) in the original baseline design to 16 GeV/u for all ions which is beneficial for the high-energy option of JLEIC of 200 GeV or higher. A scheme for adapting the new large ion booster design to also serve as electron storage ring is presented.
 
 
SUPLH11
Spin Dynamics in the JLEIC Ion Injector Linac  
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  • J.L. Martinez Marin, B. Mustapha
    ANL, Lemont, Illinois, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
One of the requirements for the future Electron Ion Col-lider (EIC) is to collide polarized electrons and light ions with at least 70% polarization for each beam. For light ions, polarized ion sources are used for injection to a linac, which is usually the first accelerator in the collider chain. The Jefferson Lab EIC (JLEIC) ion injector linac consists of a low-energy room-temperature section with quadrupole focusing followed by a superconducting linac with solenoid focusing inside long cryomodules. These two sections have different effects on the spin. Spin dy-namics simulation studies are carried out for the JLEIC injector linac in order to preserve and maintain a high degree of polarization for light ion beams for delivery to the booster. The different options to maintain and restore the spin in the different sections of the linac for hydrogen, deuterium and helium ions are presented and discussed. Results from both the Zgoubi and COSY-Infinity codes are presented and compared for every section of the ion linac but the radio-frequency quadrupole (RFQ). Current-ly, a method to simulate the RFQ using Zgoubi is being investigated.
 
 
SUPLH12
Weak-Strong Simulation of Beam-Beam Effects in Super Proton-Proton Collider  
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  • L.J. Wang, J.Y. Tang
    IHEP, Beijing, People’s Republic of China
  • T. Sen
    Fermilab, Batavia, Illinois, USA
 
  A Super Proton-Proton Collider (SPPC) that aims to explore new physics beyond the standard model is planned in China. Here we focus on the impact of beam-beam interactions in the SPPC. Simulations show that with the current optics and nominal tunes, the dynamic aperture (DA) with all the beam-beam interactions is less than 6σ, the dominant cause being the long-range interactions. First, we show the results of a tune scan done to maximize the DA. Next, we discuss the compensation of the long-range interactions by increasing the crossing angle and also by using current carrying wires.  
slides icon Slides SUPLH12 [1.250 MB]  
 
SUPLH13
Electron-Ion Collider Performance Studies With Beam Synchronization via Gear-Change  
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  • I. Neththikumara, G.A. Krafft, B. Terzić
    ODU, Norfolk, Virginia, USA
  • G.A. Krafft, Y. Roblin
    JLab, Newport News, Virginia, USA
 
  Beam synchronization of the future electron-ion collider (EIC) is studied with introducing different bunch numbers in the two colliding beams. This allows non-pairwise collisions between the bunches of the two beams and is known as "gear-change", whereby one bunch of the first beam collides with all other bunches of the second beam, one at a time. Here we report on the study of how the beam dynamics of the Jefferson Lab Electron Ion collider concept is affected by the gear change. For this study, we use the new GPU-based code (GHOST). It features symplectic one-turn maps for particle tracking and Bassetti-Erskine approach for beam-beam interactions.