Collaborative Research: R&D Towards Higher Sensitivity Directional Dark Matter Detectors

在这个精确宇宙学的时代，测量表明，普通物质只代表宇宙中总物质密度的一小部分。其余的，我们只能通过引力来推断其存在，其性质是未知的，被称为暗物质。粒子物理学认为，暗物质是由大爆炸遗留下来的弱相互作用大质量粒子（WIMP）组成的。由于小的相互作用概率和大的背景，直接检测WIMP的实验工作极具挑战性。地球在银河系中的运动产生了WIMP的逆风。来自WIMP相互作用的反冲的角分布具有~100%的不对称性，并且由于地球的旋转而以恒星速率调制。没有已知的背景可以模拟这种信号。正在开发的这种搜索技术的实际影响有希望的应用程序，低背景α和中子测量。这项工作还包括在越来越罕见的小规模实验中对不同的本科生和研究生进行培训，让他们接触到广泛的研究经验。定向反冲轨道识别（DRIFT）实验引领了定向暗物质探测领域。该奖项的智力价值在于DRIFT对这种调制签名的敏感性，这为当今科学中最重要的问题之一提供了一个独特的窗口。在过去几年中，NSF资助的DRIFT-IId工作取得了巨大的实验进展。该合作处于调试新DRIFT-IIe探测器的最后阶段。这两个探测器的运行将测试长时间无背景曝光的可行性。该奖项将为DRIFT-II的继续运营提供资金。

In this era of precision cosmology, measurements suggest that ordinary matter represents only a fraction of the total matter density in the Universe. The rest, whose presence we only infer gravitationally, is unknown in its nature, and is termed dark matter. Particle physics suggests that dark matter comprises relic Weakly Interacting Massive Particles (WIMPs) left over from the Big Bang. Experimental efforts to directly detect WIMPs are extremely challenging due to small interaction probabilities and large backgrounds. The motion of the Earth through the galaxy produces a head-wind of WIMPs. The angular distribution of recoils from WIMP interactions has a ~100% asymmetry, and is modulated at the sidereal rate on account of the Earth's rotation. No known background can mimic this signal. The practical implications of the technology being developed for such searches have promising applications to low background alpha and neutron measurements. This work also includes the training of a diverse set of undergraduates and graduate students in increasingly rare small-scale experiments, giving them exposure to a wide range of research experience.The Directional Recoil Identification From Tracks (DRIFT) experiment leads the field of directional dark matter detection. The intellectual merit of this award resides in DRIFT's sensitivity to this modulated signature, which provides a unique window into one of the most important questions in science today. NSF-funded DRIFT-IId work over the last several years has led to enormous experimental progress. The collaboration is in the final stages of commissioning a new DRIFT-IIe detector. The operation of both detectors will test the viability of long-duration background-free exposures. This award will provide funding to continue the operations of DRIFT-II.