DUSEL R&D: Development of Bolometric Detectors for Neutrinoless Double Beta Decay and Neutrino Mass Experiments

这个提议解决了中微子物理学中的两个基本问题：中微子是马约拉纳粒子还是狄拉克粒子，以及中微子的绝对质量是多少？目前解决第一个问题的唯一可行的实验技术是寻找无中微子双β衰变；第二个问题可以通过测量单个β衰变能谱端点附近的畸变来回答。可用于研究这些问题的技术数量有限，低温测热仪是唯一可以同时回答这两个问题的检测方法。拟议的研究将探讨如何提高现有中微子实验热辐射计的灵敏度水平。具体地说，我们将通过利用热和闪烁等辐射热计提供的多种信号特征来进行研究，以了解和区分放射性背景的来源。此外，还将对辐射计信号提取进行研究，以提高探测器的速度。微热量计的读数和可扩展性对于下一代使用辐射热计直接测量中微子质量至关重要。低温测热计在天文学和天体物理学研究中得到了广泛的应用。他们也在一些中微子实验（双β衰变和单β衰变端点质量测量）中找到了应用，但目前专业知识主要集中在欧洲。这里提出的研究将有助于在中微子社区发展这一有前途的技术的专业知识，以便我们准备好在DUSEL可用时使用辐射热计进行敏感的中微子质量和/或双β衰变实验。

This proposal addresses two fundamental questions in neutrino physics: Are neutrinos Majorana or Dirac particles, and what is the absolute neutrino mass? The only practical experimental technique currently available to address the first question is to search for neutrinoless double beta decay; the second can be answered by measuring the distortion near the endpoint of a single beta decay energy spectrum. A limited number of technologies are available to investigate these questions and cryogenic bolometers is the only detection method that may offer answers to both.The proposed research will investigate ways to improve on the sensitivity levels achievable with current bolometers for neutrino experiments. Specifically, we will pursue studies to understand and discriminate sources of radioactive backgrounds by making use of multiple signal characteristics available from bolometers such as heat and scintillation. In addition, R&D on the signal extraction from bolometers will be carried out to improve the detector speed. The readout and scalability of microcalorimeters is crucial for the next generation of direct neutrino mass measurement using bolometers.Cryogenic bolometers are being used extensively in astronomy and astrophysics research. They have also found application in a few neutrino experiments (double beta decay and single beta decay endpoint mass measurements), but the expertise currently resides mostly in Europe. The research proposed here will help develop the expertise of this promising technology in the neutrino community so that we are ready to pursue sensitive neutrino mass and/or double beta decay experiments using bolometers when DUSEL becomes available.