  SuperCDMS SNOLAB will be a next-generation experiment aimed at directly
detecting low-mass (< 10 GeV/c$^2$) particles that may constitute dark matter
by using cryogenic detectors of two types (HV and iZIP) and two target
materials (germanium and silicon). The experiment is being designed with an
initial sensitivity to nuclear recoil cross sections ~ 1 x 10$^{-43}$ cm$^2$
for a dark matter particle 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 detectors will be sufficient to detect nuclear recoils
from sub-GeV dark matter. A detailed calibration of the detector response to
low energy recoils will be needed to optimize running conditions of the HV
detectors and to interpret their data for dark matter searches. Low-activity
shielding, and the depth of SNOLAB, will reduce most backgrounds, but
cosmogenically produced $^{3}$H and naturally occurring $^{32}$Si will be
present in the detectors at some level. Even if these backgrounds are x10
higher than expected, the science reach of the HV detectors would be over three
orders of magnitude beyond current results for a dark matter mass of 1
GeV/c$^2$. The iZIP detectors are relatively insensitive to variations in
detector response and backgrounds, and will provide better sensitivity for dark
matter particle masses (> 5 GeV/c$^2$). The mix of detector types (HV and
iZIP), and targets (germanium and silicon), planned for the experiment, as well
as flexibility in how the detectors are operated, will allow us to maximize the
low-mass reach, 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 matter sensitivity
down to the "neutrino floor", where coherent scatters of solar neutrinos become
a limiting background.
