Author: Khachatryan, V.
Paper Title Page
MOPOST051 Study of Transverse Resonance Island Buckets at CESR 199
 
  • S. Wang, V. Khachatryan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: Work supported by NSF PHYS-1416318 and DMR-1829070.
A 6-GeV lattice with the horizontal tune near a 3rd-order resonance line at 3νx=2 is designed for studying the transverse resonance island buckets (TRIBs) at the Cornell Electron Storage Ring (CESR). The distribution of 76 sextupoles powered individually is optimized to maximize the dynamic aperture and achieve the desired amplitude-dependent tune shift αxx and the resonant driving term h30000, which are necessary conditions to form stable island buckets. The particle tracking simulations are developed to check and confirm the formation of TRIBs at different tunes with clearing kicks in this TRIBs lattice. Finally, the lattice is loaded in CESR and the TRIBs are successfully observed when the horizontal fractional tune is adjusted to 0.665, close to the 3rd-order resonance line. Bunch-by-bunch feedback is also explored to clear the particles in the main bucket and the island buckets, respectively.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST051  
About • Received ※ 20 May 2022 — Revised ※ 09 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022
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MOPOTK040 Progress on the Measurement of Beam Size Using Sextupole Magnets 550
 
  • J.A. Crittenden, H.X. Duan, A.E. Fagan, G.H. Hoffstaetter, V. Khachatryan, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work is supported by National Science Foundation award number DMR-1829070.
Variations in strength of a sextupole magnet in a storage ring result in changes to the closed orbit, phase functions and tunes which depend on the position of the beam relative to the center of the sextupole and on the beam size. Such measurements have been carried out with 6 GeV positrons at the Cornell Electron Storage Ring. The initial analysis presented at IPAC21 has been extended to both transverse coordinates, introducing additional tune shifts and coupling kicks caused by skew quadrupole terms arising from the vertical position of the positron beam relative to the center of the sextupole. Variations of strength in each of the 76 sextupoles provide measurements of difference orbits, phase and coupling functions. An optimization procedure applied to these difference measurements determines the horizontal and vertical orbit kicks and the normal and skew quadrupole kicks corresponding to the the strength changes. Continuously monitored tune shifts during the sextupole strength scans provide a redundant, independent determination of the two quadrupole terms. Following the recognition that the calculated beam size is highly correlated with the calibration of the sextupole, a campaign was undertaken to obtain precise calibrations of the sextupoles and to measure their offsets relative to the reference orbit, which is defined by the quadrupole centers. We present the measured distributions of calibration correction factors and sextupole offsets together with the accuracy in their determination.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK040  
About • Received ※ 07 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 24 June 2022  
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MOPOTK041 Magnetic Field Noise Search Using Turn-by-Turn Data at CESR 553
 
  • V. Khachatryan, J. Barley, M.H. Berry, A.T. Chapelain, D.L. Rubin, J.P. Shanks, S. Wang
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: The authors thank NSF PHYS-1416318 and DMR-1829070.
A method for searching for magnetic field noise has been developed using the CESR beam turn-by-turn data. The technique is tested using Monte-Carlo samples and turn-by-turn real data with induced noise in one of the CESR magnets. We estimate the analysis sensitivity for the noise sources slower than 4 kHz (or 100 CESR-turns) with the current CESR BPM system on the level of 1 microradian or 0.2 Gs×m field integral. In this work we report the observed noise sources and the improvements achieved by applying this technique. Long-term, several hours, beam stability analysis is also performed using the same method.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK041  
About • Received ※ 07 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 27 June 2022  
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WEPOMS030 A Path-Length Stability Experiment for Optical Stochastic Cooling at the Cornell Electron Storage Ring 2311
SUSPMF077   use link to see paper's listing under its alternate paper code  
 
  • S.J. Levenson, M.B. Andorf, I.V. Bazarov, V. Khachatryan, J.M. Maxson, D.L. Rubin, S. Wang
    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 PHY-1549132, the Center for Bright Beams and NYSTAR award C150153.
To achieve sufficient particle delay with respect to the optical path in order to enable high gain amplification, the design of the Optical Stochastic Cooling (OSC) experiment in the Cornell Electron Storage Ring (CESR) places the pickup (PU) and kicker (KU) undulators approximately 80 m apart. The arrival times at the KU of particles and the light they produce in the PU must be synchronized to an accuracy of less than an optical wavelength, which for this experiment is 780 nm. To test this synchronization, a planned demonstration of the stability of the bypass in CESR is presented where, in lieu of undulators, an interference pattern formed with radiation from two dipoles flanking the bypass is used. In addition to demonstrating stability, the fringe visibility of the pattern is related to the cooling ranges, a critical parameter needed for OSC. We present progress on this stabilization experiment including the design of a second-order isochronous bypass, as well as optimizations of the Dynamic Aperture (DA) and injection efficiency.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS030  
About • Received ※ 08 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 26 June 2022
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THPOPT066 Helical Wiggler Design for Optical Stochastic Cooling at CESR 2751
 
  • V. Khachatryan, M.B. Andorf, I.V. Bazarov, J.A. Crittenden, S.J. Levenson, J.M. Maxson, D.L. Rubin, J.P. Shanks, S. Wang
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • W.F. Bergan
    BNL, Upton, New York, USA
 
  Funding: The authors thank the Center for Bright Beams, NSF award PHY-1549132; W.F.B. was supported by the NSF Graduate Research Fellowship Program under grant number DGE-1650441.
A helical wiggler with parameter kund=4.35 has been designed for the Optical Stochastic Cooling (OSC) experiment in the Cornell Electron Storage Ring (CESR). We consider four Halbach arrays, which dimensions are optimized to get the required helical field profile, as well as, to get the best Dynamic Aperture (DA) in simulations. The end poles are designed with different dimensions to minimize the first and second field integrals to avoid the need of additional correctors for the beam orbit. The design is adopted to minimize the risks for the magnet blocks demagnetization. To quantify the tolerances, we simulated the effects of different types of geometrical and magnetic field errors on the OSC damping rates. In addition, to understand the challenges for the construction, as well as, to validate the model field calculations, we prototyped a small two period version. The prototype field is compared to the model, and the results are presented in this work.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT066  
About • Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 14 June 2022
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