First Use of a Polarized $^3$He Neutron Spin Filter on the Back-n White Neutron Source of CSNS

TL;DR

This paper reports the first successful polarization of neutrons at the CSNS Back-n beamline using an in-situ 3He neutron spin filter with spin-exchange optical pumping, enabling new fundamental physics experiments.

Contribution

It demonstrates the first use of an in-situ polarized 3He neutron spin filter at a spallation neutron source, achieving high polarization levels for neutron experiments.

Findings

Achieved 68% polarization of 3He in-situ at CSNS

Enabled polarized neutron experiments on the Back-n beamline

Demonstrated feasibility of spin-exchange optical pumping for neutron polarization

Abstract

Polarized eV neutrons can address interesting scientific questions in nuclear physics, particle physics, and astrophysics/cosmology. We present the first experiment to polarize the neutrons on the Back-n beamline at the Chinese Spallation Neutron Source (CSNS) using an in-situ NSF using spin-exchange optical pumping (SEOP) of 3He. A 3He polarization of 68%$\pm$0.7% for this in-situ NSF was measured through neutron transmission method at Back-n.This is high enough to enable new experiments on the Back-n beamline. Polarized neutron, Polarized nuclei, CSNS, White neutron, Fundamental physics research PACS number(s): 24.80.+y, 67.30.ep, 29.27.Hj , 24.70.+s , 32.10.Dk