MAX - Multi-ton Argon and Xenon TPCs

这项提案将资助由普林斯顿大学领导的研究，以寻找由弱相互作用大质量粒子（wimp）组成的暗物质存在的证据。wimp可以通过与地球上原子核的碰撞来检测，但是这种碰撞的预期率很低，反冲核的能量也很低，因此需要在地下深处的实验室中安装具有极低背景率的大型探测器。深层地下科学与工程实验室（DUSEL）的发展将使在美国部署比目前运行的WIMP探测器灵敏几个数量级的探测器成为可能。本方案计划在时间投影室（TPC）中使用液态氩气和氙作为活性介质，在TPC中可以通过大量液体独立检测闪烁和电离并进行空间分辨。利用这些信号的相对大小和时间依赖性，可以从背景中区分出核后坐力。利用这些方法和致密液体的自屏蔽能力，领先的氙和氩TPC实验已经实现了对wimp的竞争性灵敏度。该提案计划开发两项重要的新技术，这将大大增强目前合作的能力，以设计最佳的氙和氩探测器系统，用于发现和识别wimp：(1)在氙合作项目中开发了一种新的低放射性、高量子效率的混合光电倍增管，即石英光子强化探测器（Qupid），由加州大学洛杉矶分校与Hamamatsu合作设计；(2)在美国国家科学基金会的支持下，普林斯顿大学和圣母大学的研究小组发现了同位素39Ar含量低的氩气地下来源。这一提议也将为下一代更大的探测器（10吨氙TPC， 50吨贫氩TPC）做好准备。如果横截面小于10的负47次方cm**2，则需要这些仪器来检测WIMP暗物质，或者如果使用DUSEL-ISE实验发现WIMP暗物质，则需要对WIMP特性进行高统计和详细的研究。更广泛的影响：拟议的活动将以多种方式推进DUSEL及其科学和教育使命的发展：(1)通过美国大学和国家实验室与欧洲和日本团体的合作和伙伴关系，它将有助于DUSEL作为一个国际设施的知名度；(2)为培养学生提供了良好的机会，使他们有机会为基础科学和高级工程领域的前沿项目的成功做出贡献；(3)通过惰性液体探测器和相关技术在从国家安全到医学成像等领域的商业应用，使社会受益；(4)支持持续发展成功的EPO项目，如普林斯顿-阿布鲁佐-南达科他州高中生暑期学校。

This proposal will fund the search led by Princeton University for evidence to the existence of dark matter that is made of Weakly Interacting Massive Particles (WIMPs). WIMPs may be detectable by their collisions with nuclei on Earth, but the low expected rate of such collisions and low energy of the recoil nuclei requires massive detectors with extremely low background rates, located in a deep underground laboratory. The development of a Deep Underground Science and Engineering Laboratory (DUSEL) will enable the deployment within the U.S. of WIMP detectors several orders of magnitude more sensitive than those operating today. This proposal plans to use Liquid argon and xenon as the active media in Time Projection Chamber (TPC)where the scintillation and ionization can be independently detected and spatially resolved through large volumes of liquid. The discrimination of nuclear recoils from background is possible using the relative size and time dependence of these signals. By exploiting these methods and the self-shielding capability of the dense liquids, the leading xenon and argon TPC experiments have already achieved competitive sensitivity to WIMPs. This proposal plans to develop two important new technologies that will greatly enhance the power of the present collaboration to design the best xenon and argon detector system for the discovery and identification of WIMPs: (1) the development within the Xenon collaboration of a new low radioactivity, high-quantum-efficiency hybrid photomultiplier tube, the Quartz Photon Intensifying Detector or Qupid, designed at UCLA in partnership with Hamamatsu and (2) the discovery of underground sources of argon gas low in the isotope 39Ar by the Princeton and Notre Dame groups, supported by the NSF. This proposal will also prepare the way for a following generation of still-larger detectors (10 ton xenon TPC, 50 ton depleted argon TPC). These will be required to detect WIMP dark matter if the cross section is below the 10 to the minus 47 cm**2, or to perform high statistics, detailed studies of WIMP properties if WIMP dark matter is discovered using DUSEL-ISE experiments.BROADER IMPACT: The proposed activity will advance the development of DUSEL and its scientific and educational mission in a variety of ways: (1) it will help the visibility of DUSEL as an international facility, through cooperation and partnership of US universities and national laboratories with European and Japanese groups; (2) it will offer an excellent opportunity for the training of students, who will have a chance to contribute to the success of a cutting edge project in fundamental science and advanced engineering; (3) it will benefit society through commercial applications of noble liquid detectors and associated technologies in areas ranging from national security to medical imaging; (4) it will support continued development of successful EPO programs such as the Princeton-Abruzzo-South Dakota summer school for high school students.