Projected sensitivity of the SuperCDMS SNOLAB experiment

SuperCDMS SNOLAB will be a next-generation experiment aimed at directly detecting low-massparticles (with masses ≤ 10 GeV/c^2) that may constitute dark matterby using cryogenic detectorsof two types (HV and iZIP) and two target materials (germanium and silicon). The experiment is being designed with an initial sensitivity to nuclear recoilcross sections ∼ 1×10^(−43) cm^2 for a dark matterparticle mass of 1 GeV/c^2, and with capacity to continue exploration to both smaller masses and better sensitivities. The phonon sensitivity of the HV detectorswill be sufficient to detect nuclear recoilsfrom sub-GeV dark matter. A detailed calibration of the detectorresponse to low-energy recoilswill be needed to optimize running conditions of the HV detectorsand to interpret their data for dark mattersearches. Low-activity shielding, and the depth of SNOLAB, will reduce most backgrounds, but cosmogenically produced ^3H and naturally occurring ^(32)Si will be present in the detectorsat some level. Even if these backgrounds are 10 times higher than expected, the science reach of the HV detectorswould be over 3 orders of magnitude beyond current results for a dark mattermass of 1 GeV/c^2. The iZIP detectorsare relatively insensitive to variations in detectorresponse and backgrounds, and will provide better sensitivity for dark matterparticles with masses ≳ 5 GeV/c^2. The mix of detectortypes (HV and iZIP), and targets (germanium and silicon), planned for the experiment, as well as flexibility in how the detectorsare operated, will allow us to maximize the low-massreach, and understand the backgrounds that the experiment will encounter. Upgrades to the experiment, perhaps with a variety of ultra-low-background cryogenic detectors, will extend dark mattersensitivity down to the “neutrino floor,” where coherent scatters of solar neutrinosbecome a limiting background.