The Mechanics of Axionic Dark Matter Detection using 3He -21Ne Comagnetometry

Abstract

Axions are a type of elementary particle in the proposed Peccei-Quinn mechanism to resolve the strong CP problem in quantum chromodynamics (QCD). QCD Axions and axion-like particles (ALP) have been proposed as viable candidates for cold dark matter. Using nuclear spin magnetometry we seek to either detect or set limits on the mass of axionic dark matter by taking advantage of its coupling to spin. We perform 3He -21Ne comagnetometry using 87Rb detection and decoupling. We measure the ratio of 3He to 21Ne spin precession frequencies in an effort to measure physical effects that do not scale with each of the species' gyromagnetic ratios. Past experiments have achieved a typical frequency resolution of ~10 nHz for the main species' precession frequency. We seek to make improvements in both data analysis and long-term stability of the hardware to push this resolution further. We also study the physical mechanisms that cause adverse frequency shifts associated with a persisting z-polarization of the spin species and propose methods to minimize their effects.