Year: 2008
Type: article
Abstract: We discuss the precession of spin-polarized ultracold neutrons (UCNs) and $^{3}\mathrm{He}$ atoms in uniform and static magnetic and electric fields and calculate the spin relaxation effects from motional $\mathbf{v}\ifmmode\times\else\texttimes\fi{}\mathbf{E}$ magnetic fields. Particle motion in an electric field creates a motional $\mathbf{v}\ifmmode\times\else\texttimes\fi{}\mathbf{E}$ magnetic field, which when combined with collisions produces variations of the total magnetic field and results in spin relaxation of neutron and $^{3}\mathrm{He}$ samples. The spin relaxation times ${T}_{1}$ (longitudinal) and ${T}_{2}$ (transverse) of spin-polarized UCNs and $^{3}\mathrm{He}$ atoms are important considerations in a new search for the neutron electric dipole moment at the Spallation Neutron Source $n\mathrm{EDM}$ experiment. We use a Monte Carlo approach to simulate the relaxation of spins due to the motional $\mathbf{v}\ifmmode\times\else\texttimes\fi{}\mathbf{E}$ field for UCNs and for $^{3}\mathrm{He}$ atoms at temperatures below $600\phantom{\rule{0.3em}{0ex}}\mathrm{mK}$. We find the relaxation times for the neutron due to the $\mathbf{v}\ifmmode\times\else\texttimes\fi{}\mathbf{E}$ effect to be long compared to the neutron lifetime, while the $^{3}\mathrm{He}$ relaxation times may be important for the $n\mathrm{EDM}$ experiment.
Source: Physical Review A
Authors: Riccardo Schmid, B. Plaster, B. W. Filippone
Institution: California Institute of Technology
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funder: National Science Foundation
OpenAlex ID: W2091450557