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。随着未来的搜索追求更高的灵敏度和更小的相互作用截面，背景，特别是来自中子的背景，必然会出现。对于非常大的探测器来说，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不计的水平将变得不切实际。因此，当我们即将在地下深处科学与工程实验室进行暗物质搜索时，我们很可能必须脱离零背景范式，而是在众所周知的中子背景之上搜索信号。这个问题需要一种新的暗物质搜索方法。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) 寻找众所周知的中子背景之上的暗物质信号。本研究的目标是：(i) 开发使用 40-Ar 上的多重散射、非弹性散射和中子捕获来原位测量 LAr 暗物质探测器中中子背景的方法； (ii) 开发围绕暗物质探测器的主动中子否决； (iii) 在暗物质搜索中应用结合这些中子背景测量的统计工具来寻找高于背景的信号。 MiniCLEAN设计是暗物质搜索的新方向。它利用非常成功、经过验证的太阳中微子物理学方法来构建低本底探测器，可以轻松扩展到数吨目标。 MiniCLEAN 成功演示了这种暗物质方法，将为未来的超大型探测器开辟新天地。成功关键取决于背景抑制；解决困难的中子成分是该提案的重点。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大型暗物质探测器以及屏蔽其他低本底实验（包括无中微子）提供及时的输入双β衰变和低能太阳中微子实验。