Author: Hancock, S.
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MOPOR023 Flat Bunches with a Hollow Distribution for Space Charge Mitigation 652
 
  • A. Oeftiger, H. Bartosik, A. Findlay, S. Hancock, G. Rumolo
    CERN, Geneva, Switzerland
  • A. Oeftiger
    EPFL, Lausanne, Switzerland
 
  Funding: CERN, Doctoral Studentship EPFL, Doctorate
Longitudinally hollow bunches provide one means to mitigate the impact of transverse space charge. The hollow distributions are created via dipolar parametric excitation during acceleration in CERN's Proton Synchrotron Booster. We present simulation work and beam measurements. Particular emphasis is given to the alleviation of space charge effects on the long injection plateau of the downstream Proton Synchrotron machine, which is the main goal of this study.
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR023  
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TUPMR027 CERN's Fixed Target Primary Ion Programme 1297
 
  • D. Manglunki, M.E. Angoletta, J. Axensalva, G. Bellodi, A. Blas, M.A. Bodendorfer, T. Bohl, S. Cettour-Cave, K. Cornelis, H. Damerau, I. Efthymiopoulos, A. Fabich, J.A. Ferreira Somoza, A. Findlay, P. Freyermuth, S.S. Gilardoni, S. Hancock, E.B. Holzer, S. Jensen, V. Kain, D. Küchler, A.M. Lombardi, A.I. Michet, M. O'Neil, S. Pasinelli, R. Scrivens, R. Steerenberg, G. Tranquille
    CERN, Geneva, Switzerland
 
  The renewed availability of heavy ions at CERN for the needs of the LHC programme has triggered the interest of the fixed-target community. The project, which involves sending several species of primary ions at various energies to the North Area of the Super Proton Synchrotron, has now entered its operational phase. The first argon run, with momenta ranging from 13 AGeV/c to 150 AGeV/c, took place from February 2015 to April 2015. This paper presents the status of the project, the performance achieved thus far and an outlook on future plans.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMR027  
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TUPOR009 Single Bunch Longitudinal Instability in the CERN SPS 1670
SUPSS055   use link to see paper's listing under its alternate paper code  
 
  • A. Lasheen, T. Bohl, S. Hancock, T. Roggen, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  • E. Radvilas
    Gediminas Technical University, Vilnius, Lithuania
 
  The longitudinal single bunch instability observed in the SPS leads to uncontrolled emittance blow-up and limits the quality of high intensity beams required for the High Luminosity LHC and AWAKE projects at CERN. The present SPS impedance model developed from a thorough survey of machine elements was used in macro-particle simulations (with the code BLonD) of the bunch behavior through the acceleration cycle. Comparison of simulations with measurements of the synchrotron frequency shift, performed on the SPS flat bottom to probe the impedance, show a reasonable agreement. During extensive experimental studies various beam and machine parameters (bunch intensity, longitudinal emittance, RF voltage, with single and double RF systems) were scanned in order to further benchmark the SPS impedance model with measurements and to better understand the mechanism behind the instability. It was found that the dependence of instability threshold on longitudinal emittance and beam energy has an unexpected non-monotonic behavior, leading to islands of (in)stability. The results of this study are presented and can be used to define possible parameter settings for the future CERN projects.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR009  
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