Abstract
SABRE aims to directly measure the annual modulation of the dark matter interaction rate with NaI(Tl) crystals. A modulation compatible with the standard hypothesis, in which our Galaxy is immersed in a dark matter halo, has been measured by the DAMA experiment in the same target material. Other direct detection experiments, using different target materials, seem to exclude the interpretation of such modulation in the simplest scenario of WIMP-nucleon elastic scattering. The SABRE experiment aims to carry out an independent search with sufficient sensitivity to confirm or refute the DAMA claim. The goal of the SABRE experiment is to achieve the lowest background rate for a NaI(Tl) experiment (order of 0.1 cpd/kg/keVee in the energy region of interest for dark matter). This challenging goal could be achievable by operating high-purity crystals inside a liquid scintillator veto for active background rejection. In addition, twin detectors will be located in the northern and southern hemispheres to identify possible contributions to the modulation from seasonal or site-related effects. The SABRE project includes an initial Proof-of-Principle phase at LNGS (Italy), to assess the radio-purity of the crystals and the efficiency of the liquid scintillator veto. This paper describes the general concept of SABRE and the expected sensitivity to WIMP annual modulation.
Highlights
The substantial background reduction anticipated by Sodium-iodide with Active Background REjection (SABRE), namely one order of magnitude below the level reached by the DAMA experiment and not yet matched by any other NaI(Tl) experiment to date, could be achieved via ultra-high crystal radiopurity coupled with active rejection through a liquid scintillator veto
The SABRE twin detectors will be placed at Laboratori Nazionali del Gran Sasso (LNGS), Italy, and at the Stawell Underground Physics Laboratory (SUPL) in Australia, located 240 km north–west of Melbourne
SABRE aims to achieve a background at the level of 0.1 cpd/kg/ keVee via crystal purity and active rejection through a liquid scintillator veto
Summary
Direct detection experiments have been searching for interactions of dark matter candidates with Standard Model particles. The dual site is a unique feature of SABRE, with respect to other NaI(Tl) dark matter searches currently running: the COSINE-100 experiment [9] at the YangYang Laboratory in South Korea and the ANAIS experiment [10] at the Canfranc Laboratory in Spain. These experiments, even after several years of operation, might not be able to resolve all possible scenarios in interpreting the DAMA signal as a dark matter signature, given that their background levels are about 2–3 times higher than that of DAMA. The hypothesis of a focusing effect of the dark matter wind due to the gravitational potential of the Sun could be investigated [13]
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