Low background screening facility at Boulby for rare event search experiments

Boulby 的低背景筛选设施，用于罕见事件搜索实验

• 批准号: ST/L003228/1
• 负责人: Chamkaur Ghag
• 金额: $ 10.9万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FL003228%2F1
• 关键词: Low; background; screening; facility; Boulby

Scientists around the world are closing in on two of the biggest challenges in physics: understanding the nature of dark matter and the properties of the neutrino. Dark matter accounts for 85% of the mass of the Universe yet we do not know what it is since it has never been observed, and although we do know neutrinos have mass we do not know precisely how much nor if they are their own anti-particles. If they are it could explain the tiny imbalance between matter and antimatter shortly after the Big Bang. These questions have profound impact on our understanding of the Universe and its evolution - answering them is amongst the highest priorities in science.Experiments that hope to observe dark matter particle interactions or neutrinoless double beta decay events that will tell us about the neutrino share a common requirement. Since both of these processes are extremely rare the detectors need to be shielded from all sources of background radiation that might mask the signal. The first line of defence is to place the detectors deep underground in mines or under mountains - this reduces the rate of cosmic rays from space that bombard the surface of the Earth. Next the detectors are surrounded with copper, lead, plastics and water to block the radiation emitted by the underground rock. Although this is natural low-level radiation that causes no harm to humans, it is catastrophic for our extremely sensitive rare-event searches! The final and most difficult step is to construct the detectors themselves from only the purest materials that are exceptionally 'clean' in terms of trace contaminants that may emit radiation.The UK has a very strong track record and international standing in rare-event underground physics, going back several decades, and we continue to take leading roles in the most advanced experiments. We now stand on the edge of discovery with the next generation of dark matter and neutrino experiments. Unfortunately, here in the UK, our capability to screen materials to check their radio-purity before using them to build detectors is no longer sufficient. As detectors have become ever more sensitive, so has the requirement for the materials to be ever cleaner and free from even the smallest amount of radiation. Whereas previously we could rely on a germanium detector located at the Boulby Underground Laboratory to perform our screenings, it can no longer keep up with the sensitivity requirements of the dark matter and neutrino-less double beta decay experiments. This is doubly problematic because in addition to vetting material before accepting it in detector construction, we must also understand precisely the amount of radiation expected from each and every component. Only if we know what we expect from all of these materials can we hope to observe an excess and claim discovery of an exceptional signal. Very few facilities exist worldwide with germanium detectors with sufficient sensitivity to satisfy these needs.We will install a new facility at Boulby with a state-of-the art germanium detector that will be used by 15 institutes across the UK in their low background screening campaigns for the leading dark matter and neutrino-less double beta decay experiments. With this much needed capability to deliver amongst the world's most sensitive material screening tests, the Boulby facility will be reinstated as a leader in the field, and we will be able to construct the next generation of experiments that will help unravel the mysteries of the Universe.Such a facility would be very useful to a wide variety of applications well beyond particle physics and cosmology. It would significantly improve environmental radioactivity studies already in progress at Boulby, and would provide capability for studying the climate with aerosol growth and cloud formation, and next generation electronics. Internationally there is an industrial and commercial demand for such instruments with the sensitivity we would provide.

世界各地的科学家正在接近物理学中的两个最大挑战：理解暗物质的性质和中微子的性质。暗物质占宇宙质量的85%，但我们不知道它是什么，因为它从来没有被观察到，虽然我们知道中微子有质量，但我们不知道确切的数量，也不知道它们是否是自己的反粒子。如果是这样，就可以解释大爆炸后不久物质和反物质之间的微小不平衡。这些问题对我们理解宇宙及其演化有着深远的影响--回答这些问题是科学界最优先考虑的问题之一。希望观察暗物质粒子相互作用或无中微子双β衰变事件的实验，将告诉我们中微子的情况，这是一个共同的要求。由于这两种过程都非常罕见，因此探测器需要屏蔽所有可能掩盖信号的背景辐射源。第一道防线是将探测器放置在矿井或山脉的地下深处-这降低了来自太空的宇宙射线轰击地球表面的速率。接下来，探测器被铜、铅、塑料和水包围，以阻挡地下岩石发出的辐射。虽然这是天然的低水平辐射，对人类无害，但对我们极其敏感的稀有事件搜索来说，却是灾难性的！最后一步也是最困难的一步是用最纯净的材料来建造探测器，这些材料在可能释放辐射的微量污染物方面非常“干净”。英国在稀有事件地下物理学方面有着非常强大的记录和国际地位，可以追溯到几十年前，我们继续在最先进的实验中发挥主导作用。我们现在正处于下一代暗物质和中微子实验的发现边缘。不幸的是，在英国，我们在使用材料制造探测器之前筛选材料以检查其放射性纯度的能力已经不足。随着探测器变得越来越灵敏，对材料的要求也越来越高，即使是最小量的辐射也要更清洁。虽然以前我们可以依靠位于博尔比地下实验室的锗探测器来进行筛选，但它已经无法满足暗物质和无中微子双β衰变实验的灵敏度要求。这是双重问题，因为除了在接受探测器结构之前对材料进行审查外，我们还必须准确了解每个组件的预期辐射量。只有当我们知道我们对所有这些材料的期望时，我们才有希望观察到一个多余的东西，并声称发现了一个特殊的信号。目前世界上只有极少数的设施拥有足够灵敏度的锗探测器来满足这些需求。我们将在博尔比安装一个新的设施，配备最先进的锗探测器，英国15个研究所将在其领先的暗物质和中微子少的双β衰变实验的低本底筛选活动中使用该设备。有了这个急需的能力，提供世界上最敏感的材料筛选测试，博尔比设施将恢复作为该领域的领导者，我们将能够构建下一代的实验，这将有助于解开宇宙的奥秘。这样的设施将是非常有用的各种应用远远超出粒子物理学和宇宙学。它将大大改善在博尔比已经进行的环境放射性研究，并将提供研究气溶胶增长和云形成的气候的能力，以及下一代电子学。国际上有一个工业和商业的需求，这种仪器的灵敏度，我们将提供。

项目成果

Ultra-low background mass spectrometry for rare-event searches

用于罕见事件搜索的超低背景质谱

• DOI: 10.1016/j.nima.2017.10.014
• 发表时间: 2018
• 期刊: Accelerators, Spectrometers, Detectors and Associated Equipment
• 作者: Dobson J

Low Background Gamma Spectroscopy at the Boulby Underground Laboratory

Boulby 地下实验室的低本底伽马能谱

• DOI: 10.48550/arxiv.1708.06086
• 发表时间: 2017
• 作者: Scovell P

First Results of the LUX Dark Matter Experiment

• DOI: 10.1016/j.nuclphysbps.2015.09.043
• 发表时间: 2016-04
• 期刊: Nuclear and Particle Physics Proceedings
• 作者: M. Carmona-Benitez;D. Akerib;H. Araújo;X. Bai;A. Bailey;J. Balajthy;P. Beltrame;E. Bernard;A. Bernstein;A. Bradley;D. Byram;S. Cahn;C. Chan;J. Chapman;A. A. Chiller-A.;C. Chiller;A. Currie;L. D. Viveiros;A. Dobi;J. Dobson;E. Druszkiewicz;B. Edwards;C. Faham;S. Fiorucci;C. Flores;R. Gaitskell;V. Gehman;C. Ghag;K. Gibson;M. Gilchriese;C. Hall;M. Hanhardt;S. Haselschwardt;S. Hertel;M. Horn;D. Huang;M. Ihm;R. Jacobsen;K. Kazkaz;R. Knoche;N. Larsen;C. Lee;B. Lenardo;K. Lesko;A. Lindote;M. Lopes;D. Malling;A. Manalaysay;R. Mannino;D. McKinsey;D. Mei;J. Mock;M. Moongweluwan;J. Morad;A. Murphy;C. Nehrkorn;H. Nelson;F. Neves;R. Ott;M. Pangilinan;P. Parker;E. K. Pease;K. Pech;P. Phelps;L. Reichhart;T. Shutt;Catarina Silva;V. Solovov;P. Sorensen;K. O'Sullivan;T. Sumner;M. Szydagis;D. Taylor;B. Tennyson;D. Tiedt;M. Tripathi;L. Tvrznikova;S. Uvarov;J. Verbus;N. Walsh;R. Webb;J. White;M. Witherell;F. Wolfs;M. Woods;C. Zhang

Low-background gamma spectroscopy at the Boulby Underground Laboratory

Boulby 地下实验室的低本底伽马能谱

• DOI: 10.1016/j.astropartphys.2017.11.006
• 发表时间: 2018
• 期刊: Astroparticle Physics
• 影响因子: 3.5
• 作者: Scovell P

Low background screening capability in the UK

英国背景筛查能力低

• DOI: 10.1063/1.4927980
• 发表时间: 2015
• 作者: Ghag C