  The SABRE (Sodium Iodide with Active Background Rejection) experiment will
search for an annually modulating signal from dark matter particles in our
Galaxy using an array of ultra-pure NaI(Tl) detectors surrounded by an active
scintillator veto to further reduce their intrinsic background. The first phase
of the experiment is the SABRE Proof of Principle (PoP), a single 5kg crystal
detector operated in a liquid scintillator filled vessel at Laboratori
Nazionali del Gran Sasso (LNGS). The PoP installation is underway with the goal
of running in 2018 and performing the first in situ measurement of the crystal
background and testing the veto efficiency, thus validating the SABRE concept.
GEANT4--based Monte Carlo simulations have been developed to estimate the
background in the PoP. The most recent simulation is based on measured or
predicted radio-purity levels of the various detector components and includes
detailed versions of the detector part geometries. The second phase of SABRE
will be twin arrays of NaI(Tl) detectors operating at LNGS and at the Stawell
Underground Physics Laboratory (SUPL) in Australia. By locating detectors in
both hemispheres, SABRE will minimize seasonal systematic effects. In this work
the SABRE PoP activities at LNGS and results from the most recent Monte Carlo
simulations will be presented.
