TUE —  WGE - Beam Instrumentation and Interaction   (05-Oct-21   10:00—11:00)
Paper Title Page
Experimental Demonstration of Optical Stochastic Cooling  
  • J.D. Jarvis, D.R. Broemmelsiek, K. Carlson, D.R. Edstrom, D. Franck, V.A. Lebedev, S. Nagaitsev, O. Obrycki, H. Piekarz, A.L. Romanov, J. Ruan, J.K. Santucci, G. Stancari, A. Valishev
    Fermilab, Batavia, Illinois, USA
  • S. Chattopadhyay, A.J. Dick, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • I. Lobach
    University of Chicago, Chicago, Illinois, USA
  Funding: Fermi National Accelerator Laboratory is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Simon van der Meer’s Stochastic Cooling (SC) was vital in the discovery of the W and Z bosons in 1983 as it enabled sufficient accumulation of antiprotons and delivery of the required beam quality*. This execution of the innovative SC concept promptly earned van der Meer a share of the 1984 Nobel Prize in Physics. A terahertz-bandwidth extension of SC was proposed in 1993 by Mikhailichenko and Zolotorev**. This Optical Stochastic Cooling (OSC) used visible or infrared light rather than microwaves and was extended shortly after by Zolotorev and Zholents to the so-called transit-time method of OSC***. The world’s first experimental demonstration of OSC has just concluded at Fermilab’s Integrable Optics Test Accelerator (IOTA) ring. In this presentation, we will describe the OSC concept, the IOTA ring and OSC apparatus and then present the first experimental results for cooling and heating in one, two and three dimensions. We will also describe experimental studies of a single electron interacting with itself via the OSC physics.
* S. van der Meer, CERN-ISR-PO-72-31 (1972)
** A.A.Mikhailichkenko, M.S. Zolotorev, Phys. Rev. Lett. 71 (25), p. 4146 (1993)
*** M. S. Zolotorev, A. A. Zholents, Phys. Rev. E 50 (4), p. 3087 (1994)
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TUEC2 Operational Experience with Nanocrystalline Injection Foils at SNS 176
  • N.J. Evans
    ORNL RAD, Oak Ridge, Tennessee, USA
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE- AC05-00OR22725 for the U.S. Department of Energy.
The Spallation Neutron Source (SNS) uses 300-400μ g/cm2 nanocrystalline diamond foils grown in-house at the Center for Nanophase Materials Sciences to facilitate charge exchange injection (CEI) from the 1 GeV H linac into the 248~m circumference accumulation ring. These foils have performed exceptionally well with lifetimes of thousands of MW·hrs. This contribution shares some experience with the operation of these foils during 1.4 MW operation, and discusses current operational concerns including injection related losses, foil conditioning, deformation, and sublimation due to high temperatures. The implications for the SNS Proton Power Upgrade are also discussed.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-TUEC2  
About • Received ※ 17 October 2021 — Revised ※ 21 October 2021 — Accepted ※ 23 November 2021 — Issue date ※ 06 March 2022
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Fast Switching and Signal Processing Techniques for Co-Propagating Unequal Bunch Length Beams  
  • R.L. Hulsart
    BNL, Upton, New York, USA
  Obtaining accurate position measurements from BPMs in accelerators require calibration techniques to minimize the bias in the sampling channels. In many BPM electronics, filters and amplifiers are utilized to improve selectivity and dynamic range. Many of these components unfortunately have a frequency dependent response that is sensitive to the spectral content of the beam signal. Variations in bunch length and structure between two beams can lead to a bias in each channel, which becomes a challenge to remove using only a static calibration method. A scheme of rapidly swapping signals from two channels using switches installed near the BPM can be implemented to combat these issues. Bias in each path has an equal and opposite component when they are reversed. Modern solid-state RF switch ICs are available at low cost and are well suited for this purpose, having low insertion losses. Such a switching system was utilized for the LEReC project to mitigate differences between the ion and electron beam signals with good results. Details of this particular implementation as well as some general information about the switching technique will be discussed.  
slides icon Slides TUEC3 [1.136 MB]  
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TUEC4 Test of Machine Learning at the CERN LINAC4 181
  • V. Kain, N. Madysa, P.K. Skowroński, I. Vojskovic
    CERN, Geneva, Switzerland
  • N. Bruchon
    University of Trieste, Trieste, Italy
  • S. Hirlaender, G. Valentino
    University of Malta, Information and Communication Technology, Msida, Malta
  The CERN H linear accelerator, LINAC4, served as a test bed for advanced algorithms during the CERN Long Shutdown 2 in the years 2019/20. One of the main goals was to show that reinforcement learning with all its benefits can be used as a replacement for numerical optimization and as a complement to classical control in the accelerator control context. Many of the algorithms used were prepared beforehand at the electron line of the AWAKE facility to make the best use of the limited time available at LINAC4. An overview of the algorithms and concepts tested at LINAC4 and AWAKE will be given and the results discussed.  
slides icon Slides TUEC4 [2.879 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-TUEC4  
About • Received ※ 07 October 2021 — Revised ※ 21 October 2021 — Accepted ※ 23 November 2021 — Issue date ※ 19 December 2021
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