Article Title

Polarized He-3 spin filters for slow neutron physics

Type of Work

Article

Date

5-1-2005

Journal Title

Journal of Research of the National Institute of Standards and Technology

Journal ISSN

1044-677X

Journal Volume

110

Journal Issue

3

First Page

299

Last Page

304

DOI

10.6028/jres.110.043

Abstract

Polarized He-3 spin filters are needed for a variety of experiments with slow neutrons. Their demonstrated utility for highly accurate determination of neutron polarization are critical to the next generation of betadecay correlation coefficient measurements. In addition, they are broadband devices that can polarize large area and high divergence neutron beams with little gamma-ray background, and allow for an additional spin-flip for systematic tests. These attributes are relevant to all neutron sources, but are particularly well-matched to time of flight analysis at spallation sources. There are several issues in the practical use of He-3 spin filters for slow neutron physics. Besides the essential goal of maximizing the He-3 polarization, we also seek to decrease the constraints on cell lifetimes and magnetic field homogeneity. In addition, cells with highly uniform gas thickness are required to produce the spatially uniform neutron polarization needed for beta-decay correlation coefficient experiments. We are currently employing spin-exchange ( SE) and metastability-exchange ( ME) optical pumping to polarize He-3, but will focus on SE. We will discuss the recent demonstration of 75 % He-3 polarization, temperature-dependent relaxation mechanism of unknown origin, cell development, spectrally narrowed lasers, and hybrid spin-exchange optical pumping.

Notes

Article:
"Polarized He-3 spin filters for slow neutron physics," Journal of Research of the National Institute of Standards and Technology 110, 299-304 (2005). doi: 10.6028/jres.110.043.

Authors:
T.R. Gentile, W.C. Chen, G.L. Jones, E. Babcock, T.G. Walker

Hamilton Areas of Study

Physics