2011 Particle Accelerator Conference - List of Authors (Liu, J.)

Paper	Title	Page
WEP125	Higher-order Spin Resonances in 2.1 GeV/c Polarized Proton Beam	1716
	M.A. Leonova, J. Askari, K.N. Gordon, A.D. Krisch, J. Liu, D.A. Nees, R.S. Raymond, D.W. Sivers, V.K. Wong University of Michigan, Spin Physics Center, Ann Arbor, MI, USA F. Hinterberger Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany V.S. Morozov JLAB, Newport News, Virginia, USA
	Funding: This research was supported by grants from the German Science Ministry Spin resonances can cause partial or full depolarization or spin-flip of a polarized beam. We studied 1st-, 2nd- and 3rd-order spin resonances with a 2.1 GeV/c vertically polarized proton beam stored in the COSY Cooler Synchrotron. We observed almost full spin-flip when crossing the 1st-order Ggamma=8−nu_y vertical-betatron-tune spin resonance and partial depolarization near some 2nd- and 3rd-order resonances. We observed almost full depolarization near the 1st-order Ggamma=8−nu_x horizontal spin resonance and partial depolarization near some 2nd- and 3rd-order resonances. Moreover, we found that a 2nd-order nu_x resonance seems about as strong as some 3rd-order nu_x resonances, while some 3rd-order nu_y resonances seem much stronger than a 2nd-order nu_y resonance. It was thought that, for flat accelerators, vertical spin resonances are stronger than horizontal, and lower order resonances are stronger than higher order ones. The data suggest that many higher-order spin resonances, both horizontal and vertical, must be overcome to accelerate polarized protons to high energies; the data may help RHIC to better overcome its snake resonances between 100 and 250 GeV/c.

Paper

Title

Page

Higher-order Spin Resonances in 2.1 GeV/c Polarized Proton Beam

1716

M.A. Leonova, J. Askari, K.N. Gordon, A.D. Krisch, J. Liu, D.A. Nees, R.S. Raymond, D.W. Sivers, V.K. Wong
University of Michigan, Spin Physics Center, Ann Arbor, MI, USA
F. Hinterberger
Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn, Germany
V.S. Morozov
JLAB, Newport News, Virginia, USA

Funding: This research was supported by grants from the German Science Ministry
Spin resonances can cause partial or full depolarization or spin-flip of a polarized beam. We studied 1st-, 2nd- and 3rd-order spin resonances with a 2.1 GeV/c vertically polarized proton beam stored in the COSY Cooler Synchrotron. We observed almost full spin-flip when crossing the 1st-order G*gamma=8−nu_y vertical-betatron-tune spin resonance and partial depolarization near some 2nd- and 3rd-order resonances. We observed almost full depolarization near the 1st-order G*gamma=8−nu_x horizontal spin resonance and partial depolarization near some 2nd- and 3rd-order resonances. Moreover, we found that a 2nd-order nu_x resonance seems about as strong as some 3rd-order nu_x resonances, while some 3rd-order nu_y resonances seem much stronger than a 2nd-order nu_y resonance. It was thought that, for flat accelerators, vertical spin resonances are stronger than horizontal, and lower order resonances are stronger than higher order ones. The data suggest that many higher-order spin resonances, both horizontal and vertical, must be overcome to accelerate polarized protons to high energies; the data may help RHIC to better overcome its snake resonances between 100 and 250 GeV/c.