Distinguishing Dark Matter Signals from Neutron Backgrounds

区分暗物质信号和中子背景

• 批准号: 0970047
• 负责人: Joseph Formaggio
• 金额: $ 40.5万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0970047&HistoricalAwards=false
• 关键词: Distinguishing; Dark; Matter; Signals; Neutron

The nature of dark matter is one of the great mysteries in physics. Direct signals for dark matter have remained elusive. As future searches push to greater sensitivities and smaller interaction cross sections, backgrounds, especially from neutrons, will necessarily arise. Reducing these backgrounds to a negligible level through greater underground depths and more shielding will become impractical for very large detectors. Thus, as we move toward the time when dark matter searches will be performed at the Deep Underground Science and Engineering Laboratory, it is likely that we may have to depart from the zero-background paradigm, instead searching for signals above a well understood neutron background. This problem calls for a new approach to dark matter searches. The research objective of this award is a search for a dark matter signal above a well understood neutron background, using a liquid Argon (LAr) dark matter detector (MiniCLEAN) underground in SNOLab. The goals of this research are: (i) to develop methods for measuring the neutron background in-situ in LAr dark matter detectors using multiple scattering, inelastic scattering, and neutron capture on 40-Ar; (ii) to develop an active neutron veto surrounding the dark matter detector; and (iii) to apply statistical tools incorporating these neutron background measurements in a dark matter search for signal above background. The MiniCLEAN design is a new direction for dark matter searches. It draws on highly successful, proven approaches of solar neutrino physics to building low-background detectors that scale simply to multi-tonne targets. Successful demonstration of this approach for dark matter by MiniCLEAN will break new ground for future, very large detectors. Success depends critically on background suppression; addressing the difficult neutron component is the focus of this proposal.Broader impacts: Measurements of the neutron flux using these new methods will provide timely input to designing future large dark matter detectors, as well as shielding for other low background experiments, including neutrino-less double beta decay and low-energy solar neutrino experiments.

暗物质的本质是物理学中最大的谜团之一。暗物质的直接信号仍然难以捉摸。随着未来的研究向更高的灵敏度和更小的相互作用截面推进，背景，特别是来自中子的背景，必然会出现。通过更大的地下深度和更多的屏蔽将这些背景降低到可以忽略的水平对于非常大的探测器来说是不切实际的。因此，当我们走向在深地下科学与工程实验室进行暗物质搜索的时候，我们可能不得不离开零背景范式，而不是搜索高于中子背景的信号。这个问题需要一种新的方法来寻找暗物质。该奖项的研究目标是使用SNOLab地下的液态氩（LAr）暗物质探测器（MiniCLEAN）在一个很好理解的中子背景之上寻找暗物质信号。本研究的目标是：（一）开发的方法，用于测量中子背景在LAR暗物质探测器使用多次散射，非弹性散射，和中子捕获40-Ar;（二）开发一个积极的中子否决周围的暗物质探测器;和（三）应用统计工具，将这些中子背景测量在暗物质搜索信号以上的背景。MiniCLEAN设计是暗物质搜索的新方向。它借鉴了太阳中微子物理学非常成功的、经过验证的方法来建造低背景探测器，这些探测器可以简单地扩展到多吨级的目标。MiniCLEAN对暗物质的这种方法的成功演示将为未来的超大型探测器开辟新的天地。更广泛的影响：使用这些新方法测量中子通量将为设计未来的大型暗物质探测器提供及时的输入，以及为其他低本底实验提供屏蔽，包括中微子少的双β衰变和低能太阳中微子实验。