SABRE R&D: Investigating radio-pure Sodium Iodide

多个天文观测已经确定，宇宙中大约85%的物质不是由已知粒子组成的。破译这种所谓的暗物质的性质对宇宙学、天体物理学和高能粒子物理学具有根本的重要性。一个主要的假设是，它是由弱相互作用大质量粒子（WIMP）组成的，这些粒子是在大爆炸后产生的。如果WIMP是暗物质，那么它们在我们星系中的存在可能是通过位于地下深处的探测器中的原子核散射来检测的，以帮助排除宇宙射线造成的背景。位于意大利格兰萨索地下实验室的DAMA是唯一一个声称发现暗物质相互作用的实验，他们观察到了预测的信号速率的年度调制。最近一些实验（CoGeNT、CRESST和CDMS-Si）的结果可能支持弱相互作用大质量粒子（WIMP）的解释，而其他实验（KIMS-CsI、LUX和XENON-100等）则不支持。只有使用NaI（Tl）的实验才能进行模型无关检验。SABRE（主动背景抑制碘化钠）实验将为这一争论提供线索，从而指导未来的直接检测搜索。SABRE项目为学生和博士后研究人员提供了充足的机会，以获得在科学界工作的经验和培训。SABRE正在与普林斯顿教师准备项目办公室协商，讨论为当地高中学生和教师提供额外教育和专业发展机会的潜在方法。SABRE项目在工业界和学术界之间建立了牢固的关系。他们与工业界的合作伙伴关系使新技术，产品和测量技术的开发成为可能，这些技术将提供给整个研究和工业市场。由该奖项资助的SABRE研发工作旨在通过开发比DAMA具有更低背景和更低能量阈值的NaI（Tl）探测器来为这种探测器提供原理证明。在生产高纯碘化钠粉末方面已经取得了进展，这些粉末的杂质含量与DAMA中的最终晶体相似或更低。进一步纯化的潜力已被其晶体生长器与区域精炼所证明。

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.