Collaborative Research: Direct Search for Dark Matter with Underground Argon at LNGS

合作研究：在 LNGS 中用地下氩直接寻找暗物质

• 批准号: 1314483
• 负责人: C J Martoff
• 金额: $ 52.64万
• 依托单位: Temple University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-15 至 2018-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1314483&HistoricalAwards=false
• 关键词: Collaborative; Research; Direct; Search; Dark

The existence of dark matter is inferred from gravitational effects, but its nature remains a deep mystery. One possibility, motivated by considerations in elementary particle physics, is that dark matter consists of the hypothesized Weakly Interacting Massive Particles (WIMPs). It should be possible to detect WIMPs directly, as the orbital motion of the WIMPs composing the dark matter halo pervading the galaxy should result in WIMP-nucleus collisions of sufficient energy to be observable in the laboratory. This collaboration utilizes funds to commission and operate DarkSide-50, a WIMP search using a Liquid Argon Time Projection Chamber (LAr-TPC) with an active mass of 50 kg. DarkSide-50 will use argon extracted from underground sources (Underground Argon, UAr), which this group has shown to have an Ar-39 content lower, by at least a factor of 150, than atmospheric argon. Ar-39 is one of the main sources of background in the experiment.A significant by-product of this group's research has been developing techniques that could find application in areas ranging from national security to medical imaging. This arises from the extraction of rare noble gases (Argon and Helium) from underground sources, and possible applications include the detection of underground nuclear tests and in Environmental Science where Argon is used as a detection media in ultra-low level proportional counter measurements for an environmental radio tracer for hydrologic transport.Liquid argon is an attractive medium for WIMP detection due to its efficient conversion of energy from WIMP-induced nuclear recoils into both ionization and scintillation. The argon scintillation time profile ("pulse shape") depends on the type of ionizing particle, providing particle discrimination that can be used to suppress background. Pulse shape discrimination in argon provides one of the most powerful background rejections among all dark matter technologies; when combined with the measurement of ionization, the background rejection is further enhanced. The proposed activity will advance the development of astroparticle physics and its scientific and educational mission by: (1) offering a continuing excellent opportunity for the training of students, who will contribute to the success of a cutting-edge project; (2) developing techniques that could find application in several areas of benefit to society; and (3) supporting a new education and outreach program, designed to succeed the highly successful Laboratori Nazionali del Gran Sasso-South Dakota-Princeton summer school.

暗物质的存在是从引力效应推断出来的，但它的性质仍然是一个谜。一种可能性是，基于基本粒子物理学的考虑，暗物质由假设的弱相互作用大质量粒子（WIMP）组成。直接探测WIMP应该是可能的，因为构成弥漫星系的暗物质晕的WIMP的轨道运动应该会导致WIMP与核的碰撞，其能量足以在实验室中观测到。这项合作利用资金委托和运行DarkSide-50，这是一个使用有效质量为50公斤的液体氩时间投影室（LAr-TPC）的WIMP搜索。DarkSide-50将使用从地下来源提取的氩气（地下氩气，UAr），该小组已证明其Ar-39含量比大气氩气低至少150倍。 Ar-39是该实验的主要背景来源之一。该小组研究的一个重要副产品是开发可应用于从国家安全到医学成像等领域的技术。 这是从稀有稀有气体中提取出来的（氩和氦）来自地下资源，可能的应用包括地下核试验的探测，以及在环境科学中，氩被用作超低水平正比计数器测量水文输运的环境放射性示踪剂的探测介质。液态氩是一种有吸引力的WIMP探测介质，因为它能有效地转换WIMP的能量。诱发核反冲，使其电离和闪烁。氩闪烁时间曲线（“脉冲形状”）取决于电离粒子的类型，提供可用于抑制背景的粒子辨别。氩气中的脉冲形状鉴别提供了所有暗物质技术中最强大的背景抑制之一;当与电离测量相结合时，背景抑制进一步增强。拟议的活动将通过以下方式推动天体粒子物理学的发展及其科学和教育使命：（1）为培训学生提供持续的极好机会，这些学生将为尖端项目的成功作出贡献;（2）开发可在有益于社会的若干领域得到应用的技术;以及（3）支持一个新的教育和推广计划，旨在接替非常成功的大萨索-南达科他-普林斯顿暑期学校。