Polarized ^{3}He^{+2} ions in the Alternate Gradient Synchrotron to RHIC transfer line

Abstract

The proposed electron-hadron collider (eRHIC) to be built at Brookhaven National Laboratory (BNL) will allow the collisions of 20 GeV polarized electrons with 250 GeV polarized protons, or 100 GeV/n polarized ^{3}He^{+2} ions, or other unpolarized ion species. The large value of the anomalous magnetic moment of the ^{3}He nucleus G_{He}=(g-2)/2=-4.184 (where g is the g-factor of the ^{3}He nuclear spin) combined with the peculiar layout of the transfer line which transports the beam bunches from the Alternate Gradient Synchrotron (AGS) to the Relativistic Heavy Ion Collider (RHIC) makes the transfer and injection of polarized ^{3}He ions from AGS to RHIC (AtR) a special case as we explain in the paper. Specifically in this paper we calculate the stable spin direction of a polarized ^{3}He beam at the exit of the AtR line which is also the injection point of RHIC, and we discuss a simple modifications of the AtR beam-transfer-line, to perfectly match the stable spin direction of the injected polarized ^{3}He beam to that of the circulating beam, at the injection point of RHIC.