Relaxation of Spin Polarized $^3$He in Mixtures of $^3$He and $^4$He at $\sim$330 mK

Abstract

We report the measurements of depolarization probabilities of polarized 3 He in a rectangular acrylic cell with a deuterated tetraphenyl butadiene-doped deuterated polystyrene coating filled with superfluid 4 He at ∼330 mk with a magnetic holding field of ∼7.3 G. We achieve a wall depolarization probability of ∼ 1.0 × 10 −7 . Such a surface will find application in a new experiment searching for the neutron electric dipole moment and other applications.

Simulations of the nEDM@SNS light collection system efficiency

“…EUV photons have short absorption lengths in nearly all materials other than helium, so they must be converted into optical wavelengths by a WLS coating on the measurement cell walls. A coating made by dissolving deuterated tetraphenyl butadiene (dTPB) [10][11][12] and deuterated polystyrene (dPS) [13] in deuterated toluene has been shown to retain the 3 He polarization [14] and neutron density [4] for times that are long relative to the neutron beta decay lifetime. Some of the photons that enter the dTPB coating as EUV photons are converted to blue wavelengths and collected by Kuraray Y-11 WLS fibers pressed against the measurement cell wall near the ground electrode.…”