SABRE R&D: Investigating radio-pure Sodium Iodide

Princeton University, Princeton NJ

Investigators

Abstract

Multiple astronomical observations have established that about 85% of the matter in the universe is not made of known particles. Deciphering the nature of this so-called Dark Matter is of fundamental importance to cosmology, astrophysics, and high-energy particle physics. A leading hypothesis is that it is comprised of Weakly Interacting Massive Particles, or WIMPs, that were produced moments after the Big Bang. If WIMPs are the dark matter, then their presence in our galaxy may be detectable via scattering from atomic nuclei in detectors located deep underground to help reject backgrounds due to cosmic rays. DAMA at the Gran Sasso underground laboratory in Italy is the only experiment claiming a discovery of dark matter interactions from their observation of a predicted annual modulation of the signal rate. Recent results from some experiments (CoGeNT, CRESST, and CDMS-Si) may support the light WIMP (Weakly Interacting Massive Particle) interpretation, while others do not (KIMS-CsI, LUX, and XENON-100, among others). Only an experiment using NaI(Tl) can perform a model-independent test. The SABRE (Sodium-iodide with Active Background REjection) experiment would shed light on this debate and thus direct future direct-detection searches. The SABRE project provides ample opportunities for students and postdoctoral researchers to gain experience and training for careers in the scientific community. SABRE is consulting with the Princeton Teacher Preparation Program office to discuss potential ways to provide additional educational and professional development opportunities for local high-school students and teachers. The SABRE project engenders strong relationships between industry and academia. Their partnerships with industry enable the development of new technologies, products, and measurement techniques that will be made available to the research and industrial market at large. The SABRE R&D effort, funded by this award, aims to provide a proof-of-principle for such a detector by developing NaI(Tl) detectors with lower backgrounds and a lower energy threshold than DAMA. Progress has been made in producing highly pure NaI powders that now exhibit impurities at a similar level to, or lower than, the final crystals in DAMA. The potential for further purification has been demonstrated by their crystal grower with zone-refining.