Collaborative Research: A Depleted Argon Detector for a Dark Matter Search

暗物质的存在是从引力效应中得知的，但它的性质仍然是一个谜。在基本粒子物理学的其他考虑中，一种可能性是暗物质由未发现的基本粒子组成。轴子和弱相互作用大质量粒子（WIMPs）是两种可能性。WIMPS由环绕银河系和地球的暗物质晕组成，它的热运动应该会导致WIMP与核的碰撞，其能量足以被灵敏的实验室仪器观测到。该奖项旨在开发和部署一个小型液氩探测器，该探测器具有高灵敏度，可直接探测WIMP碰撞。这一探测器，DarkSide-50，建立在过去的经验基础上，并引入了创新的功能，使其能够在无背景模式下运行，从而实现了重要的科学成果，尽管其体积相对较小。同时，该探测器将作为未来多吨级探测器的原型。主要的创新是：-地下氩贫化放射性39 Ar;-低背景，高量子效率QUPID光电探测器;和-紧凑的高效率外部中子否决。这些创新，加上强大的双参数背景抑制特性的氩，将导致探测器前所未有的无背景性能。DarkSide-50要么探测到WIMP暗物质，要么排除大部分有利的参数空间。DarkSide-50将受益于由NSF通过普林斯顿大学拨款独立资助的贫化氩提取和精炼设施。更广泛的影响：这一活动将以各种方式促进天体粒子物理学的发展及其科学和教育使命：（1）它将为培训学生提供一个极好的机会，使他们有机会为基础科学和先进工程方面的尖端项目的成功作出贡献;（2）它将通过开发可在从国家安全到医学成像等领域应用的技术来造福社会;（3）它将支持继续发展成功的&EO计划，如面向高中生的莱顿-阿布鲁佐-南达科他州暑期学校。

The existence of dark matter is known from gravitational effects, but its nature remains a deep mystery. One possibility motivated by other considerations in elementary particle physics is that dark matter consists of undiscovered elementary particles. Axions and Weakly Interacting Massive Particles (WIMPs) are two possibilities. The thermal motion of the WIMPS comprising the dark matter halo surrounding the galaxy and the earth should result in WIMP-nuclear collisions of sufficient energy to be observable by sensitive laboratory apparatus.This award is to develop and deploy a small liquid argon detector that has high sensitivity for direct detection of WIMP collisions. This detector, DarkSide-50, builds on past experience and introduces innovative features that will allow it to operate in a background-free mode and thereby achieve a significant science result in spite of its relatively small size. At the same time, this detector will serve as a prototype for a future multi-ton detector. The main innovations being introduced:- Underground argon depleted in radioactive 39Ar;- Low background, high-quantum-efficiency QUPID photo-detectors; and- A compact high-efficiency external veto for neutrons.These innovations, together with the powerful two-parameter background rejection features of argon will result in a detector of unprecedented background-free performance. DarkSide-50 will either detect WIMP dark matter or exclude a substantial fraction of the favored parameter space. DarkSide-50 will benefit from the facility for extraction and refinement of depleted argon, independently funded by the NSF through a grant to Princeton University. Broader Impacts: this activity will advance the development of astroparticle physics and its scientific and educational mission in a variety of ways: (1) it will offer an excellent opportunity for the training of students, who will have a chance to contribute to the success of a cutting edge project in fundamental science and advanced engineering; (2) it will benefit society by developing techniques that could find application in areas ranging from national security to medical imaging; (3) it will support continued development of successful E&O programs such as the Princeton-Abruzzo-South Dakota summer school for high school students.