Development of a Polarized Helium-3 Source for RHIC and eRHIC

J Maxwell,C Epstein,E Beebe,A Zelenski,J Alessi,A Pikin,R Milner,J Ritter

doi:10.1142/s2010194516601022

Abstract

The addition of a polarized 3He ion source for use at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory would enable a host of new measurements, particularly in the context of a planned eRHIC. We are developing such a source using metastability exchange optical pumping to polarize helium-3, which will be then transferred into RHIC’s Electron Beam Ion Source for ionization. We aim to deliver nuclear polarization of near 70%, and roughly 10[Formula: see text] doubly-ionized 3He[Formula: see text] ions will be created in each 20 [Formula: see text]sec pulse. We discuss the design of the source, and the status of its development.

Highlights

A polarized neutron beam would provide a crucial tool in the exploration of nucleon structure, especially with the advent of an electron–ion collider
Our efforts have been concentrated on the polarization and transfer of polarized gas in regions of field gradients
In the summer of 2014, a second polarizing apparatus was assembled at BNL to perform tests to assess the viability of two options for the final source design: low field or high field MEOP

Summary

Introduction

A polarized neutron beam would provide a crucial tool in the exploration of nucleon structure, especially with the advent of an electron–ion collider. Metastability exchange optical pumping[4] offers an convenient method to provide EBIS with pure samples of polarized 3He gas at the required rates. The short time scale before extraction and very high field inside EBIS result in very small expected depolarization from charge exchange with any remaining singly ionized helium or from recombination with free electrons. Performing MEOP in the space near the 5 T magnet, as well as transferring the polarized gas into EBIS, may be subject to significant depolarization from magnetic field gradients.

Development Status

Low Field Polarization

Findings

High Field Polarization