Crygenic Detector Work for SuperCDMS and Beyond

从星系和超星系团到遥远的超新星和宇宙微波背景辐射的广泛观测告诉我们，宇宙中大约85%的物质不是由普通粒子组成的，而是以某种黑暗的形式存在。破译这种暗物质的性质对宇宙学、天体物理学和高能粒子物理学具有根本的重要性。一个主要的假设是，它是由弱相互作用大质量粒子（WIMP）组成的，这些粒子是在大爆炸后产生的。如果WIMP存在并且是暗物质，那么它们在我们银河系中的存在可以通过地面探测器中原子核的散射来检测。低温暗物质搜索（CDMS）合作组织率先使用低温声子介导的设备来检测WIMP在原子核上的罕见散射，并将它们与背景区分开来。凭借这项强大的技术，他们在明尼苏达州苏丹矿井深处使用30个探测器进行了为期四年的CDMS-II实验，并在高WIMP质量下获得了全球最佳极限。该奖项将资助该小组的基本计划，主要集中在探测器表征和优化，全尺寸CDMS生产探测器的快速周转初始低温筛选，探测器生产线上钨膜样品的快速周转Tc测试，探测器制造支持，与新CDMS探测器制造和衬底抛光设施的科学家和技术人员的合作，协助进行清洁发展机制相关材料分析。它的科学成果不仅对天体物理学和粒子物理学很重要，而且它的技术发展也将推动声子介导探测器的发展，其应用越来越广泛。除了与圣克拉拉大学（SCU）的本科生合作外，PI还积极指导其他CDMS机构的本科生，研究生和初级研究人员。SCU靠近斯坦福大学、加州大学伯克利分校和SLAC，这使得与这些团体的密切合作变得特别容易，对SCU的学生也非常有益。最后，SCU小组在旧金山弗朗西斯科与K-12学生进行了一些外展，并支持苏丹的公共外展计划，作为SuperCDMS合作的一部分。

A broad range of observations -- from galaxies and superclusters to distant supernovae and the cosmic microwave background radiation -- tell us that about 85% of the matter in the universe is not made of ordinary particles, but exists in some dark form. Deciphering the nature of this dark matter is of fundamental importance to cosmology, astrophysics, and high-energy particle physics. A leading hypothesis is that it is comprised of Weakly Interacting Massive Particles, or WIMPs, that were produced moments after the Big Bang. If WIMPs exist and are the dark matter, then their presence in our Milky Way may be detectable via scattering from atomic nuclei in a terrestrial detector.The Cryogenic Dark Matter Search (CDMS) Collaboration has pioneered the use of cryogenic phonon-mediated devices to detect the rare scattering of WIMPs on nuclei and distinguish them from backgrounds. With this powerful technology, they have operated for four years the CDMS-II experiment with 30 detectors deep underground in the Soudan mine in Minnesota, and obtained the best limit worldwide at high WIMP masses. This award will fund the base program of this group to focus primarily on detector characterization and optimization, rapid-turnaround initial cryogenic screening of full-scale CDMS production detectors, rapid-turnaround Tc-testing of tungsten film samples from the detector production line, detector fabrication support, collaborative work with scientists and technical staff at new CDMS detector fabrication and substrate polishing facilities, and assistance with CDMS-related materials analysis. Not only are its scientific results important for astrophysics and particle physics, but its technological development will also push the envelope of phonon-mediated detectors, whose applications are increasingly widespread. In addition to working with students from Santa Clara University (SCU), an undergraduate institution, the PI actively mentors undergraduates, graduate students and junior research staff at other CDMS institutions. The close proximity of SCU to Stanford, UC Berkeley and SLAC makes close collaborations with these groups particularly easy - and tremendously beneficial to SCU students. Lastly, the SCU group does some outreach with K-12 students in the San Francisco Bay Area and supports the public outreach program at Soudan as part of the SuperCDMS collaboration.