Neutrinos and Dark Matter

First Results on Dark Matter Cross-Section with Liquid Argon

In July 2017, the DEAP-3600 collaboration published its first paper reporting on the search for Weakly Interacting Massive Particles (WIMPs) using four days of data collected during the commissioning phase. While the data showed no interactions between the liquid argon atoms and WIMPs (as expected based on the short exposure time), the result showed the true power of DEAP’s Pulse-Shape Discrimination (PSD), a methodology that differentiates electronic interactions (backgrounds) to nuclear interactions (signal). In Physics Review Letters, the collaboration showed that the experiment is performing to specifications and PSD can discriminate electronic recoils from nuclear recoils with an unprecedented measured power of 1.2x10-7.