Potential Dark Matter Detector? The Detection of Low Energy Neutrons by Superfluid 3He.

Abstract

Using an existing experiment we have demonstrated in a pilot study that superfluid ${}^{3}$He at 100 \ensuremath{\mu}K can be used as a nuclear recoil detector sensitive to neutron and $\ensuremath{\gamma}$ interactions depositing energies down to a few hundred eV. The deposited energy is converted to ${}^{3}$He quasiparticles which are detected by their damping effect on a vibrating wire resonator in the liquid. The system can be calibrated independently but a convenient fixed point is provided by the exothermic reaction $n+_{2}^{3}H\mathrm{e}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}p+_{1}^{3}H+764$ keV. Given the great potential for improvement we propose that the system might make a sensitive weakly interacting massive particle detector.