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Polarization Analysis using Polarized 3HeOne possible application for polarized 3He is to measure the polarization of a neutron beam. A particularly interesting use for this is in small angle neutron scattering. (Follow this link to learn more about the NIST SANS Program).Here is a drawing of the SANS apparatus. An initially polarized neutron beam is incident from the left, passes through a spin flipper (which reverses the direction of the neutron spin when on), and hits the sample. A small fraction of the beam is scattered, analyzed by the 3He spin filter, and is measured in the detector in the evacuated flight tube.
There are many applications of polarized neutrons in materials science. As an example, we have chosen small angle neutron scattering (SANS). Although supermirrors can be used to polarize or analyze cold neutrons, they cannot be used in divergent beams, such as the beam exiting the sample in a SANS apparatus. This limitation, which has prevented the use of polarization analysis in SANS experiments, can be avoided by using polarized 3He to analyze the scattered beam.
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