Development of a Spin-Exchange Optical Pumping-Based Polarized ^3He System at the China Spallation Neutron Source (CSNS)

Polarized ^3He neutron spin filters (NSFs) can be used as a vital tool for neutron polarization production and analysis. The China Spallation Neutron Source (CSNS), as one of the major neutron facilities in China, has committed resources to the development of a polarized ^3He NSF program to support its growing polarized neutron research. A spin-exchange optical pumping (SEOP)-based polarized ^3He system and other necessary hardware for NSF transport has been recently developed. The performance of the system is benchmarked using an in-house developed cell named “Trident”. Neutron beam measurements yield a ^3He polarization of 77% with over 200 h of on-beam relaxation time. Combining this newly developed SEOP system with the recently reported cell fabrication station, CSNS is now capable of the fully self-sustained production of ^3He NSFs that shall support its future neutron polarization research.