Author: Ahrens, L.
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WEPRO070 Overcoming the Horizontal Depolarizing Resonance in the Brookhaven AGS 2112
 
  • H. Huang, L. Ahrens, M. Bai, M. Blaskiewicz, K.A. Brown, R. Connolly, Y. Dutheil, W. Fischer, C.J. Gardner, J.W. Glenn, T. Hayes, F. Méot, A. Poblaguev, V.H. Ranjbar, T. Roser, V. Schoefer, K.S. Smith, S. Tepikian, N. Tsoupas, K. Yip, A. Zelenski, K. Zeno, S.Y. Zhang
    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.
Imperfection and vertical intrinsic depolarizing resonances have been overcome by the two partial Siberian snakes in the AGS. The relatively weak but numerous horizontal resonances are the main source of polarization loss in the AGS. A pair of horizontal quads have been used to overcome these weak resonances. This technique needs very accurate jump timing. Fast roll-over magnet cycle has been used and it improves the polarization transmission efficiency near extraction when acceleration usually is slowing down. Emittance preservation is also important to mitigate polarization loss. Recent experimental results including jump quad timing and emittance preservation are presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO070  
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WEPRO071 Optics Setup in the AGS and AGS Booster for Polarized Helion Beam 2115
 
  • H. Huang, L. Ahrens, J.G. Alessi, M. Bai, E.N. Beebe, M. Blaskiewicz, K.A. Brown, Y. Dutheil, W. Fischer, C.J. Gardner, J.W. Glenn, T. Hayes, F. Méot, A. Poblaguev, V.H. Ranjbar, T. Roser, V. Schoefer, K.S. Smith, S. Tepikian, N. Tsoupas, K. Yip, A. Zelenski, K. Zeno
    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.
Future RHIC physics program calls for polarized He3 beam. The He3 beam from the new EBIS source has a relative low rigidity which requires delicate control of injection and RF setup in the Booster. The strong depolarization resonance strength in both AGS and AGS Booster requires careful consideration of beam energy range and optics setup. Recently, the He3 beam was accelerated to 11GeV/n in the AGS. The near term goal fo 3*1010 at RHIC requires several RF bunch merges in both AGS and the Booster. The beam test results are presented in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO071  
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THPRO089 New Tune Jumps Scheme in the Low Energy Part of the AGS Cycle 3092
 
  • Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, V. Schoefer
    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.
During the early part of the acceleration of polarized protons, due to strong optical deformations of the lattice, the tune cannot be placed in the spin gap and the first two vertical intrinsic resonances are crossed. Recent multiparticle trackings using the Zgoubi code show that the spin resonances around Gg=5 could cause as much as 5% loss of polarization. The slow acceleration rate, the two vertical and two horizontal intrinsic spin resonances can contribute to the depolarization in the region. While in the current scheme only the two horizontal intrinsic resonances are jumped, it was proposed to use the tune jumps system to also accelerate the crossing of the two weak vertical intrinsic resonances and improve the polarization transmission through this region. We show the design of this new tune jumps scheme and the expected polarization gains expected from multiparticles Zgoubi simulations. We also compare experimental measurements of the polarization transmission to the Zgoubi simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO089  
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THPRO090 Energy Calibration and Tune Jumps Efficiency in the pp AGS 3095
SUSPSNE052   use link to see paper's listing under its alternate paper code  
 
  • Y. Dutheil, L. Ahrens, H. Huang, F. Méot, A. Poblaguev, V. Schoefer, K. Yip
    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 AGS tune jump system consists of two fast quadrupoles used to accelerate the crossing of 82 horizontal intrinsic spin resonances. The fast tune jump of ΔQh=+0.04 within 100 μs imposes perfect localization of each of the 82 resonant conditions. Imperfect timing of the tune jumps results in lower efficiency of the system and lower transmission of the polarization through the AGS acceleration cycle. Investigations during the end of the pp AGS Run13 revealed weaknesses in the energy measurement at high energy, causing less than optimal timing of the tune jumps. A new method based on continuous polarization measurement to determine the energy during the acceleration cycle has been developed. Strong operational constraints were taken into account to provide a convenient system of energy measurement. This is also used to calibrate the usual determination of the energy based on revolution frequency of the beam or measured dipole magnetic field. This paper shows the tools developed and the results of the first tests during the AGS Run 14. Simulations of the expected tune jumps efficiency using the AGS Zgoubi model are also presented and compared to experimental results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO090  
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THPRO091 Strength of Horizontal Intrinsic Spin Resonances in the AGS 3098
 
  • Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, T. Roser, V. Schoefer
    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.
Crossing of horizontal intrinsic resonances is today the main source of polarization losses in the AGS, in its dual partial snakes configuration for polarized proton acceleration. Polarization losses were greatly reduced by the AGS tune jump system. However total polarization transmission through the AGS cycle is not yet achieved, still partially due to the horizontal intrinsic resonances. This paper will explore the effect of optical distortions and different horizontal tunes on the strength of horizontal intrinsic resonances. Various options will be presented and practicability will be addressed. Theoretical model and multiparticle trackings using the Zgoubi code will show the expected polarization gains of different scenarios.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO091  
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