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Search for galactic dark matter and double beta decay measurement using a detector of new principle

使用新原理探测器寻找星系暗物质和双β衰变测量

基本信息

批准号：
04402005
负责人：
MINOWA Makoto
金额：
$ 23.17万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1995
项目状态：
已结题

项目摘要

A dedicated dilution refrigerator has been constructed. It is capable of cooling the detector material down to 10mK.It is made of specially selected raw materials to reduce natural radiation background from them.In order to manufacture thermistors with high sensitivities at low temperature, neutron transmutation doping method was adopted.Neutron irradiation has been done at the JRR-3 reactor of the Japan Atomic Energy Reasearch Institute.Using these building elements, we developed cryogenic particle detectors consisting of 8 pieces of 20-gram lithium fluoride bolometers. The lithium fluoride is known to be the material which has the largest cross section for the detection of spin dependently interacting supersymmetric neutralinos. With these detectors a direct experimental search for supersymmetric particle dark matter has been performed and is still ongoing in the Nokogiri-yama underground cell of the institute for the Cosmic Ray Research, University of Tokyo.On the basis of a pilot run, limits were obtained on normalized point-like cross section for the spin-dependently interacting neutralino incident on a single proton, although the dark matter is not yet deiscovered.While the shielding against back-ground radiation is not fully optimized yet, our search gave the worls best limits for the spin-dependently interacting neutralino with a mass lower than 5 GeV.It demonstrates the advantages of using the fluorine for the target and the low energy threshold of the bolometer. Thwe search continues with the improved shielding and more efficient veto counters.

已经建造了专用的稀释冰箱。它能将探测器材料冷却到10 mK。它是由特殊选择的原材料制成的，以减少它们的自然辐射背景。为了在低温下制造高灵敏度的热敏电阻，采用了中子嬗变掺杂方法。中子辐照已在日本原子能研究所的JRR-3反应堆上进行。使用这些建筑元件，我们开发了由8个20克氟化锂测辐射热计组成的低温粒子探测器。氟化锂是目前已知的探测自旋相关超对称中性伴子截面最大的材料。利用这些探测器，在东京大学宇宙线研究所的Nokogiriyama地下室中进行了对超对称粒子暗物质的直接实验研究，并在试运行的基础上，得到了与自旋相关的中性伴子入射到单个质子上的归一化点状截面的极限，尽管暗物质还没有被发现。尽管对背景辐射的屏蔽还没有完全优化，我们的研究给了世界上最好的旋转极限-实验结果表明，用氟作靶具有能量阈值低的优点，测辐射热计的。我们继续研究改进的屏蔽和更有效的否决计数器。