Request for continued operation and study of the ZEPLIN II dark matter detector

请求继续运行和研究 ZEPLIN II 暗物质探测器

• 批准号: 0653459
• 负责人: Hanguo Wang
• 金额: --
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0653459&HistoricalAwards=false
• 关键词: Request; continued; operation; study; ZEPLIN

Large scale astronomical observations, including expansion, galaxy clustering, gravitational lensing and microwave background, indicate that the universe is dominated by unidentified dark matter whose total mass exceeds that of normal (baryonic) matter by a factor 5-10. A favored dark matter candidate is a massive particle interacting only weakly with normal matter but nevertheless producing rare nuclear recoils detectable in suitable targets such as liquid xenon.This UCLA group requests funding for the continued running and performance improvements for the 32 kg two-phase ZEPLIN II liquid Xenon dark matter detector which is now running in the UK Boulby Mine. The program is based on a new technique for identifying low energy nuclear recoils from dark matter collisions, using scintillation and ionization processes in liquid xenon. After completion of laboratory tests in 2005, the detector was installed underground and initial runs with neutron and gamma sources show primary S1 and secondary S2 scintillation pulses in accordance with expectation, and with neutron and gamma populations having different mean values of the parameter S2/S1. New work needed includes the investigation and prevention of radon influx into the detector, removal of radon decay products from interior surfaces, improvements to data acquisition, improved event selection, and reduction of energy threshold by a more efficient trigger. The detection of particle dark matter would open a new window in astronomy and particle physics, with more advanced detectors able to determine both details of the particle properties and the spectrum and flow of the dark matter in our Galaxy. It will thus transform and extend world activities in the particle physics and astronomical communities. Moreover, the techniques themselves can be further scaled up and applied to other fundamental experiments such as double beta decay, and solar neutrinos. As with other particle detection techniques, new methods of position sensitivity and particle discrimination may give rise to new medical diagnostic techniques.

大规模的天文观测，包括膨胀、星系团、引力透镜和微波背景，表明宇宙是由未知的暗物质主导的，其总质量超过正常（重子）物质的5-10倍。 一个受欢迎的暗物质候选者是一种大质量粒子，它与正常物质的相互作用很弱，但却能产生罕见的核反冲，在合适的目标（如液体氙）中可以检测到。加州大学洛杉矶分校的这个小组要求为32公斤的两相ZEPLIN II液体氙暗物质探测器的持续运行和性能改进提供资金，该探测器目前正在英国博尔比矿运行。该计划是基于一种新的技术，用于识别低能量核反冲暗物质碰撞，使用闪烁和电离过程中的液体氙。在2005年完成实验室测试后，探测器被安装在地下，中子和伽马源的初始运行显示出符合预期的初级S1和次级S2闪烁脉冲，中子和伽马总体具有不同的参数S2/S1平均值。 新的工作需要包括调查和防止氡流入探测器，从内表面去除氡衰变产物，改进数据采集，改进事件选择，并通过更有效的触发降低能量阈值。粒子暗物质的探测将为天文学和粒子物理学打开一扇新的窗口，更先进的探测器将能够确定我们银河系中暗物质的粒子特性以及光谱和流动的细节。因此，它将改变和扩大粒子物理学和天文学界的世界活动。此外，这些技术本身可以进一步扩大规模，并应用于其他基础实验，如双β衰变和太阳中微子。与其他粒子检测技术一样，位置灵敏度和粒子鉴别的新方法可能会产生新的医学诊断技术。