Author: Safranek, J.A.
Paper Title Page
MOPPR001 Resonant Spin Depolarisation Measurements at the SPEAR3 Electron Storage Ring 771
  • K.P. Wootton, R.P. Rassool
    The University of Melbourne, Melbourne, Australia
  • M.J. Boland, Y.E. Tan
    ASCo, Clayton, Victoria, Australia
  • W.J. Corbett, M.H. Donald, X. Huang, R.R. Ortiz, J.A. Safranek, K. Tian
    SLAC, Menlo Park, California, USA
  Accurate electron beam energy measurements are valuable for precision lattice modelling of high-brightness light sources. At SPEAR3 the beam energy was measured using the resonant spin depolarisation method with striplines to resonantly excite the spin tune and a sensitive NaI scintillator beam loss monitor was used to detect resulting changes in Touschek lifetime. Using the combined apparatus an electron beam energy of 2.997251(7) GeV was measured, giving a relative uncertainty better than 3x10-6. The measured momentum compaction factor was found to be in close agreement with the numerical model value using rectangular defocussing gradient dipoles with measured magnetic field map profiles. In this paper we outline the chosen experimental technique, with emphasis on its applicability to electron storage rings in general.  
TUPPC096 Optimization of the Dynamic Aperture for SPEAR3 Low-emittance Upgrade 1380
  • L. Wang, X. Huang, Y. Nosochkov, J.A. Safranek
    SLAC, Menlo Park, California, USA
  • M. Borland
    ANL, Argonne, USA
  A low emittance upgrade is planned for SPEAR3. As the first phase, the emittance is reduced from 10nm to 7nm without addition magnets. A further upgrade with even lower emittance will require a damping wiggler. There is a smaller dynamic aperture for the lower emittance optics due to the stronger nonlinearity. A Multi-Objective Genetic Optimization (MOGA) code is used to maximize the dynamic aperture. Both the dynamic aperture and beam lifetime are optimized simultaneously. Various configurations of the sextupole magnets have been studied in order to find the best configuration. The betatron tune also can be optimized to minimize resonance effects. The optimized dynamic aperture increases 15% from the normal case and the life time increases from 15 hours to 17 hours. It is important that the increase of the dynamic aperture is mainly in the beam injection direction. Therefore the injection efficiency will benefit from this improvement.