Perspective for development of a source of highly polarized 3He- ions

Abstract

High beam polarization is essential to the scientific productivity of a collider. Polarized 3 He ions are an essential part of the nuclear physics programs at existing and future ion-ion and electron-ion colliders such as BNL's RHIC and eRHIC and JLab's ELIC. Ion sources with performance exceeding those achieved today are a key requirement for the development of these next generation high-luminosity highpolarization colliders. A new version of a polarized 3 He -ion source is needed.In this article it is proposed a polarized 3 He -ion source based on the large difference of the autodetachment lifetimes of the different 3 He -ion hyperfine states. The highest momentum state of 5/3 has the largest lifetime of τ~350 μs while the lower momentum states have lifetimes of τ ~10 μs. By producing a 3 He -ion beam composed of only the |5/2, 5/2> hyperfine states and then quenching one of the states by an RF resonant field, 3 He-beam polarization of 95% can be achieved. A high-brightness arcdischarge ion-source can produce 3 He -beams with ~1mA current with ~90% polarization. An integrated 3 He -ion source design providing high beam polarization could be prepared based on existing BNL equipment that incorporates new designs of the 1) arc discharge plasma generator, 2) extraction system, 3) charge exchange jet, and 4) optimized magnetic separation system. The formation, extraction, and transport of the ion beams in the new source should be computer simulated. Manufacturing techniques should be explored using new materials and fabrication costs should be evaluated. The advanced 3 He -ion source can be built and tested on the BNL Test Stand for further use in the ion-ion RHIC and ion-electron colliders..