RUI: Superheated Emulsions for the Detection of Dark Matter

天体物理学中最持久的谜团之一是对令人信服的证据的解释，即在星星以上的几乎所有尺度上，以不可见的形式存在的引力物质比所有已知类型的辐射都要多得多。 亚原子粒子标准模型的一般扩展预测了弱相互作用大质量粒子（WIMPS）的存在，它们是暗物质的绝佳候选者。它们与普通物质的相互作用非常弱，因此极难被探测到。 PICASSO小组已经着手开发一种新的大型暗物质探测器，该探测器来自于众所周知的气泡室技术。在该应用中，检测器由悬浮在诸如聚合物或水性凝胶的顺应性材料中并保持在过热状态（即，高于沸点）。在这种亚稳态下，液滴可以被与WIMP碰撞后反冲的原子核蒸发。在这种快速相变期间发出的声音可以使用声学传感器记录。该技术的成熟，沿着以相对较低的成本增加目标尺寸的能力以及对特定类型的辐射进行定制响应的可能性，使过热乳剂成为暗物质研究的前沿。PICASSO将成为世界上最灵敏的探测器之一，用于研究暗物质和WIMP之间的自旋相关相互作用。 南本德的印第安纳州大学的PI负责声音传感器及其相关电子设备，并负责测量PICASSO探测器的声学特性。PI还将负责测量探测器材料的氡放射和扩散。放射性分析设施也将可用于其他低本底实验。 更广泛的影响：加强科学专业和教育专业的教育是该计划的一个组成部分。印第安纳州大学SB的三名物理专业学生参与了这项工作。他们开发了一个数据采集系统，设计了一种以独特方式耦合到压电传感器的设备，该设备目前正在申请专利，并设计了将用于2kg PICASSO探测器的换能器。 教育专业和当地教师将有基于探究的科学经验，并将编写书面技术报告，他们将在合作会议上口头辩护。参加过一个真实的科学项目将告知科学教学时，他们在课堂上。一个中等科学教育专业的学生目前正在与PI合作，为2公斤实验生产了所需的300个传感器中的75个，并帮助开发了用于传感器测试的快速循环环境室。

One of the most enduring mysteries in astrophysics is the explanation for the compelling evidence that, on virtually all scales above the size of a star, far more gravitating material exists in an invisible form than that which can be detected by all known types of radiation. Generic extensions of the standard model of subatomic particles predict the existence of Weakly Interacting Massive Particles (WIMPS), which are excellent candidates for the dark matter. These are expected to interact very weakly with ordinary matter, and thus be extremely difficult to detect. The PICASSO group has undertaken the development of a new large dark matter detector derived from the well-known bubble chamber technique. In this application, the detector consists of a uniform emulsion of micron-sized halocarbon droplets suspended in a compliant material such as a polymeric or aqueous gel and kept in a superheated state (i.e., above their boiling point.) In this meta-stable state, the droplets can be vaporized by a nucleus recoiling from a collision with a WIMP. Sound emitted during this rapid phase transition can be recorded using acoustic sensors. The maturity of the technique, along with the ability to increase the target size at relatively low cost and the possibility of tailoring the response to specific types of radiation, have brought superheated emulsions to the forefront of dark matter investigations. PICASSO will be among the world's most sensitive detectors in the investigation of spin-dependent interactions between dark matter and WIMPs. The PI on this proposal at Indiana University, South Bend is responsible for sound sensors and their associated electronics, and for measuring acoustic properties of the detectors for PICASSO. The PI will also be responsible for measuring radon emanation from, and diffusion through, detector materials. The radioassay facility will also be available for use in other low background experiments. PICASSO will be sited at SNOLAB.Broader impacts: Enhancing the education of science majors and education majors is an integral part of this program. Three physics majors have participated in the work at Indiana University SB. They developed a data acquisition system, designed a device to couple to piezoelectric sensors in a unique fashion which is now being patented, and designed the transducer that will be used in the 2kg PICASSO detector. Education majors and local teachers will have inquiry-based science experiences and will produce written technical reports that they will defend orally at a collaboration meeting. Having participated in a real science project will inform the teaching of science when they are in the classroom. One secondary science education major is currently working with the PI and has produced 75 of the required 300 transducers for the 2 kg experiment and has helped to develop a rapid-cycling environment chamber for transducer testing.