"Ultracold Neutron Polarimetry in Beta Decay Angular Correlation Measurements"

The measurement of angular correlations in polarized free neutron decay can 
provide both high-precision values of Standard Model parameters as well as 
probes of new physics at the TeV scale. Ubiquitous in such high-precision 
experiments is the need for multiple approaches, which help shed light on 
systematic effects. Two such usefully complementary techniques in the 
measurement of beta decay angular correlations involve either ultracold 
neutrons (UCN) or cold neutron beams. In both cases determination of the 
neutron polarization is critical, yet in the case of UCN it is accomplished 
using techniques that differ significantly from those used with higher energy 
neutrons. Taking the UCNA experiment, which measures the beta asymmetry with 
UCN, as a prototypical example, I will discuss the technology and techniques 
which accompany the precise measurement of UCN polarization in the context 
of beta decay angular correlation measurements.