Sample preparation equipment for ultra low background screening with ICP-MS

用于 ICP-MS 超低背景筛查的样品制备设备

• 批准号: ST/M006891/1
• 负责人: Chamkaur Ghag
• 金额: $ 12.72万
• 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: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FM006891%2F1
• 关键词: Sample; preparation; equipment; ultra; low

'Dark Matter' - a mysterious substance that holds the galaxies together makes up an incredible 85% of the mass of the Universe. It is believed by many to be made up of Weakly Interacting Massive Particles (WIMPs) - but they have not yet been detected experimentally. This is because they bounce off atoms only very rarely and weakly such that their presence is extremely difficult to detect. Despite this, scientists have been working on constructing sensitive detectors capable of registering WIMP interactions should they occur. The trouble is that there are many other particles interacting in these detectors that may mask the few and faint WIMPs.Since WIMPs will interact so rarely the experiments must be shielded from all the cosmic-rays bombarding Earth from space, forcing them deep underground. However, this is still not enough to provide the quiet environment required; they are therefore shielded from natural radioactivity found in underground rock - harmless to us but catastrophic to the sensitive devices. A final background remains, coming from the very materials the detectors are made from. Tiny amounts of uranium and thorium produce signals by radioactive decay that are often indistinguishable from those expected from WIMPs. This means that extensive material screening campaigns must be conducted to select only the purest materials in constructing detectors.Developing ever more sensitive detectors in the hunt for WIMPs has demanded ever-cleaner construction materials. However, we have now reached a technological maturity such that our next detectors could have the sensitivity theoretically predicted to finally detect Dark Matter. The trouble is that capability to screen materials from which to construct them has not kept pace. We have traditionally relied on 'High Purity Germanium' detectors (HPGe) to measure materials before using them to build experiments. However, HPGe requires many weeks to screen a single sample - unacceptable when we need to check hundreds of materials in the coming years. Furthermore, HPGe cannot actually measure U and Th directly. Instead it measures elements that U and Th decay into.Inductively Coupled Plasma Mass Spectrometry (ICPMS) is capable of measuring U and Th directly. It cannot tell us about the decay products from U and Th as HPGe can, but together they produce the complete picture we need. Moreover, the time taken to screen materials - about a day or less, is just what is called for in building the next generation of experiment. However, ICPMS requires all materials to be 'prepared' - dissolved in acid and introduced as a liquid. ICPMS will only achieve high sensitivity if the materials are digested, prepared and introduced cleanly. With traditional techniques, heating materials in open glassware exposed to the elements, sensitivity can suffer dramatically.This proposal is to enhance the UK's existing ICPMS with closed microwave ashing and digestion ovens with ultra-pure, high concentration, aggressive acids, to support the UK's Dark Matter R&D programme. Such new capability would give incredible sensitivity, in only hours. This would elevate the UK's R&D programme to unique world-class status now and well into the future, at a time when internationally HPGe and ICPMS facilities are struggling to cope with demand and do not possess enough sensitivity.It will also aid other rare event searches that require ultra-low activity, such as those seeking to observe neutrino-less double beta decay. These experiments could tell us about the fundamental properties of neutrinos, and in doing so explain the tiny imbalance between particles and anti-particles shortly after the Big Bang needed for any matter to exist today. ICPMS also has powerful application in food safety, pharmaceutical, environmental, forensic and clinical studies, where elemental analysis of low levels of contaminants is a rich area of research with significant societal and economic impact potential.

“暗物质”-一种将星系结合在一起的神秘物质，占宇宙质量的85%。许多人认为它是由弱相互作用大质量粒子（WIMPs）组成的-但它们尚未被实验检测到。这是因为它们很少从原子上反弹，而且很弱，因此它们的存在极难被检测到。尽管如此，科学家们一直致力于构建灵敏的探测器，以便在WIMP相互作用发生时进行记录。问题是，在这些探测器中有许多其他粒子相互作用，这可能会掩盖少数微弱的WIMP。由于WIMP相互作用如此之少，实验必须屏蔽所有从太空轰击地球的宇宙射线，迫使它们深入地下。然而，这仍然不足以提供所需的安静环境;因此，它们与地下岩石中发现的天然放射性相屏蔽-对我们无害，但对敏感设备造成灾难性影响。最后一个背景仍然存在，来自探测器的材料。微量的铀和钍通过放射性衰变产生的信号通常与WIMP的预期信号难以区分。这意味着必须进行广泛的材料筛选活动，以选择最纯净的材料来建造探测器。为了寻找WIMP，开发更灵敏的探测器需要更清洁的建筑材料。然而，我们现在已经达到了技术成熟度，我们的下一个探测器可以具有理论上预测的灵敏度，最终探测到暗物质。问题在于，筛选材料的能力还没有跟上。我们传统上依赖于“高纯锗”探测器（HPGe）来测量材料，然后再使用它们来构建实验。然而，HPGe需要数周的时间来筛选单个样品-当我们需要在未来几年检查数百种材料时，这是不可接受的。此外，HPGe实际上不能直接测量U和Th。电感耦合等离子体质谱（ICPMS）能够直接测量U和Th。它不能像HPGe一样告诉我们U和Th的衰变产物，但它们一起产生了我们需要的完整图像。此外，筛选材料所需的时间-大约一天或更少，正是构建下一代实验所需要的时间。然而，ICPMS要求所有材料都要“准备好”-溶解在酸中并作为液体引入。只有在材料消化、制备和引入干净的情况下，ICPMS才能达到高灵敏度。采用传统技术，在敞开的玻璃器皿中加热材料，暴露在自然环境中，灵敏度会受到极大影响。该提案旨在通过使用超纯、高浓度、侵蚀性酸的封闭式微波灰化和消解炉来增强英国现有的ICPMS，以支持英国的暗物质研发计划。这种新能力将在几个小时内提供令人难以置信的灵敏度。这将使英国的研发计划在现在和将来都达到世界一流的水平，而目前国际上的HPGe和ICPMS设施都在努力科普需求，而且没有足够的灵敏度。这也将有助于其他需要超低放射性的罕见事件的搜索，例如那些寻求观察中微子较少的双β衰变的人。这些实验可以告诉我们中微子的基本性质，并在这样做的过程中解释了大爆炸后不久粒子和反粒子之间的微小不平衡，这是今天任何物质存在所必需的。ICPMS在食品安全、制药、环境、法医和临床研究中也有强大的应用，其中低水平污染物的元素分析是一个具有重大社会和经济影响潜力的丰富研究领域。

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

Signal yields, energy resolution, and recombination fluctuations in liquid xenon

• DOI: 10.1103/physrevd.95.012008
• 发表时间: 2017-01-19
• 期刊: PHYSICAL REVIEW D
• 影响因子: 5
• 作者: Akerib, D. S.;Alsum, S.;Zhang, C.
• 通讯作者: Zhang, C.

Improved Limits on Scattering of Weakly Interacting Massive Particles from Reanalysis of 2013 LUX Data.

• DOI: 10.1103/physrevlett.116.161301
• 发表时间: 2015-12
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: D. Akerib;H. Araújo;X. Bai;A. Bailey;J. Balajthy;P. Beltrame;E. Bernard;A. Bernstein;T. Biesiadzinski;E. Boulton;A. Bradley;R. Bramante;S. Cahn;M. Carmona-Benitez;C. Chan;J. Chapman;A. A. Chiller-A.;C. Chiller;A. Currie;J. Cutter;T. Davison;L. de Viveiros;A. Dobi;J. Dobson;E. Druszkiewicz;B. Edwards;C. Faham;S. Fiorucci;R. Gaitskell;V. Gehman;C. Ghag;K. Gibson;M. Gilchriese;C. Hall;M. Hanhardt;S. Haselschwardt;S. Hertel;D. Hogan;M. Horn;D. Huang;C. Ignarra;M. Ihm;R. Jacobsen;W. Ji;K. Kazkaz;D. Khaitan;R. Knoche;N. Larsen;C. Lee;B. Lenardo;K. Lesko;A. Lindote;M. Lopes;D. Malling;A. Manalaysay;R. Mannino;M. F. Marzioni;D. Mckinsey;D. Mei;J. Mock;M. Moongweluwan;J. Morad;A. Murphy;C. Nehrkorn;H. Nelson;F. Neves;K. O'Sullivan;K. Oliver-Mallory;R. Ott;K. Palladino;M. Pangilinan;E. K. Pease;P. Phelps;L. Reichhart;C. Rhyne;S. Shaw;T. Shutt;C. Silva;V. Solovov;P. Sorensen;S. Stephenson;T. Sumner;M. Szydagis;D. Taylor;W. Taylor;B. Tennyson;P. Terman;D. Tiedt;W. To;M. Tripathi;L. Tvrznikova;S. Uvarov;J. Verbus;R. Webb;J. White;T. J. Whitis;M. Witherell;F. Wolfs;K. Yazdani;S. Young;C. Zhang

Tritium calibration of the LUX dark matter experiment

• DOI: 10.1103/physrevd.93.072009
• 发表时间: 2015-12
• 期刊: Physical Review D
• 影响因子: 5
• 作者: D. Akerib;H. Araújo;X. Bai;A. Bailey;J. Balajthy;P. Beltrame;E. Bernard;A. Bernstein;T. Biesiadzinski;E. Boulton;A. Bradley;R. Bramante;S. Cahn;M. Carmona-Benitez;C. Chan;J. J. Chapman-J. ;A. A. Chiller-A.;C. Chiller;A. Currie;J. Cutter;T. Davison;L. de Viveiros;A. Dobi;J. Dobson;E. Druszkiewicz;B. Edwards;C. Faham;S. Fiorucci;R. Gaitskell;V. Gehman;C. Ghag;K. Gibson;M. Gilchriese;C. Hall;M. Hanhardt;S. Haselschwardt;S. A. Hertel;D. P. Hogan;M. Horn;D. Huang;C. Ignarra;M. Ihm;R. Jacobsen;W. Ji;K. Kazkaz;D. Khaitan;R. Knoche;N. Larsen;C. Lee;B. Lenardo;K. Lesko;A. Lindote;M. Lopes;D. Malling;A. Manalaysay;R. Mannino;M. F. Marzioni;D. Mckinsey;D. Mei;J. Mock;M. Moongweluwan;J. Morad;A. Murphy;C. Nehrkorn;H. Nelson;F. Neves;K. OSullivan;K. Oliver-Mallory;R. Ott;K. Palladino;M. Pangilinan;E. K. Pease;P. Phelps;L. Reichhart;C. Rhyne;S. Shaw;T. Shutt;C. Silva;V. Solovov;P. Sorensen;S. Stephenson;T. Sumner;M. Szydagis;D. Taylor;W. Taylor;B. Tennyson;P. Terman;D. Tiedt;W. To;M. Tripathi;L. Tvrznikova;S. Uvarov;J. Verbus;R. Webb;J. White;T. J. Whitis;M. Witherell;F. Wolfs;S. Young;C. Zhang

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