Materia Oscura: Instrumentation Development to Observe the Invisible

本项目旨在利用STFC核心科学计划支持的一个领域的专业知识，即为暗物质和中微子物理开发的超精密放射性测量和量热法，并将这些技术应用于测量水和食物中的铅污染问题。铅污染是世界上预期寿命减少的首要原因，目前世界上十大最严重的污染问题中有两个与铅有关[PureEarth2016]。这在中低收入国家和高收入国家都是一个问题——最近的例子，如美国密歇根州弗林特市的水安全违规事件表明，违反世卫组织准则的水质在任何地方都可能发生，而有关水质及其随时间变化的信息并不普遍。即使是“清洁”技术，如电动汽车，也使用传统的铅基电池；这些电池的处置是铅污染的主要原因，特别是在中低收入国家。这项提案的目的是让任何有手机的人都能测量出水中的铅污染。目前，这种测量需要昂贵的专用设备或6个月的测量才能达到对人类健康的相关灵敏度水平——即使是百万分之0.1的铅污染也会产生毁灭性的生物影响。发展移动电话检测能力使广泛分布的计量和实时、群众来源的监测成为可能，因此将对与铅污染有关的公共卫生问题产生变革性影响。虽然基于手机的放射性测定已经有了用于高能和高速率放射性衰变的原型，但目前还没有任何东西可以测定铅。达到铅所需的灵敏度水平是一个非常具有挑战性的问题，我们建议利用DAMIC和DMTPC暗物质实验开发的硅（Si）探测器中的精密量热法技术，以及DEAP-3600暗物质实验开发的铅测定一致性方法来解决这个问题，该方法可以提供超过传统技术的高达10,000的背景抑制因子。我们的最终目标是开发一个手机应用程序来测量水样中铅的存在。该应用程序将使用手机硅传感器（摄像头）进行放射性检测，目标是达到世界卫生组织对饮用水中铅污染的限制，即十亿分之十（ppb）的灵敏度水平。

This project aims to draw on an area of expertise supported by the STFC core science programme, ultra-precise radioactivity measurement and calorimetry developed for dark matter and neutrino physics, and develop application of these techniques to the problem of measuring lead contamination in water and food.The motivation for growing capacity for and developing new lead measurement techniques is that lead pollution is the #1 cause of loss of life expectancy in the world, and currently 2 of the top 10 worst pollution problems in the world are associated with lead [PureEarth2016]. This is a problem both in LMICs and in high income countries- recent examples like the Flint, Michigan, USA, water safety breaches demonstrate that water quality in violation of WHO guidelines can happen anywhere, and information about water quality, and its variation in time, is not widespread. Even 'clean' techologies, like electric cars, employ traditional lead-based batteries; the disposal of these batteries is a leading contributor to lead pollution, particularly in LMICs.The work in this proposal aims to make lead water contamination measurements accessible to anyone with a mobile phone. Currently, such measurements require expensive, specialized equipment or 6-month measurements to reach relevant sensitivity levels for human health- even 0.1 parts per million contamination with lead produces devastating biological impacts. Developing mobile-phone assay capability makes widely-distributed metrology and real-time, crowd-sourced monitoring possible, and therefore would have transformative impact on the public health problems associated with lead pollution. While mobile-phone based radioassay has been prototyped for higher-energy and higher-rate radioactive decays, nothing exists currently to assay lead. Reaching the sensitivity levels required for lead is an incredibly challenging problem, which we propose to address by leveraging the precision calorimetry techniques in silicon (Si) detectors developed by the DAMIC and DMTPC dark matter experiments, together with the lead assay coincidence methodology developed by the DEAP-3600 dark matter experiment that gives a factor of up to 10,000 in background suppression beyond conventional techniques. Our ultimate goal is to to develop a mobile phone application to measure the presence of lead in water samples. The app will employ the phone Si sensor (the camera) to perform radio-assay, with the goal of reaching the 10 parts per billion (ppb) sensitivity level, which is the World Health Organization limit on lead contamination in drinking water.