MAX - Multi-ton Argon and Xenon TPCs

这项提议将资助普林斯顿大学领导的寻找暗物质存在的证据，暗物质是由弱相互作用大质量粒子（WIMPs）组成的。WIMP可以通过与地球上的原子核碰撞来检测，但是这种碰撞的低预期速率和反冲原子核的低能量需要位于地下实验室深处的具有极低背景速率的大型探测器。深层地下科学与工程实验室（DUSEL）的发展将使美国境内部署的WIMP探测器比目前运行的探测器灵敏几个数量级。该提案计划使用液态氩和氙作为时间投影室（TPC）中的活性介质，其中闪烁和电离可以通过大量液体独立检测和空间分辨。利用这些信号的相对大小和时间依赖性，可以区分核反冲与背景。通过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力量，以设计用于发现和识别WIMP的最佳氙和氩探测器系统：（1）在氙合作项目内开发一种新的低放射性、高量子效率的混合光电倍增管，即石英光子增强探测器或Qupid，在加州大学洛杉矶分校与滨松合作设计，（2）由美国国家科学基金会支持的普林斯顿和圣母大学小组发现了同位素39 Ar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）铺平道路。如果横截面小于10的负47 cm**2，则需要这些来探测WIMP暗物质，或者如果使用DUSEL-ISE实验发现WIMP暗物质，则需要这些来进行高统计，详细研究WIMP属性。更广泛的影响：拟议的活动将以各种方式推进DUSEL的发展及其科学和教育使命：（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，它将有助于提高DUSEL作为一个国际设施的知名度;（2）为培养学生提供了一个极好的机会，谁将有机会为基础科学和先进工程的尖端项目的成功做出贡献;（3）通过将惰性液体探测器及其相关技术在国家安全和医学成像等领域的商业应用，造福社会;（4）它将支持继续发展成功的EPO项目，如面向高中生的莱顿-阿布鲁佐-南达科他州暑期学校。

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.