Probing low-mass WIMPs with tetrafluoroethane superheated liquid detectors

Abstract

Probing low mass (sub-GeV -- few GeV) Weakly Interacting Massive Particle (WIMP) candidates of Dark Matter through WIMP-induced nuclear recoils in Direct Detection experiments requires use of detector materials consisting of low mass target nuclei and low threshold energy. Here we explore the potential of superheated liquid detectors (SLD) with a hydrogen containing liquid, namely, tetrafluoroethane (C$_{2}$H$_{2}$F$_{4}$) (b.p.: $-26.3^\\circ\\,$C), as the target material for probing low mass WIMPs. It is argued that, depending on the operating temperature, threshold energies of $\\sim$ 0.2 keV may be possible, which would allow WIMPs of masses down to sub-GeV level to be probed. For example, under the assumption of 100% detector efficiency, a C$_{2}$H$_{2}$F$_{4}$ SLD operated at $55^\\circ\\,$C with a total exposure of 1000 kg.day would be able to probe WIMPs of mass $\\sim$ 5, 1 and 0.3 GeV at the spin-independent WIMP-nucleon cross section ($\\sigma_{\\chi n}^{\\rm SI}$) sensitivity levels of $\\sigma_{\\chi n,90}^{\\rm SI} \\sim 6.4\\times10^{-8}, \\, 6.1\\times10^{-7}$ and $5.6\\times10^{-4}$ pb, respectively, where $\\sigma_{\\chi n,90}^{\\rm SI}$ is the 90% C.L. Poisson upper limit on $\\sigma_{\\chi n}^{\\rm SI}$ for zero observed events and no background.