Development of ultra-fast photon detection systems

核物理、强子物理和粒子物理的未来实验依赖于所有反应产物的四动量矢量的识别和完整、精确的测定。成像切伦科夫探测器是提供这些信息的宝贵工具。当带电粒子以大于光速的速度穿过介质时，在介质中会产生切伦科夫辐射。这个圆锥的开口角（对于辐射体介质的给定折射率）是粒子速度的度量。这提供了一个强大的方法，结合一个独立的力矩测量来推断粒子的质量。目前正在开发的成像切伦科夫检测器可以分为两类，经典的环形成像切伦科夫（RICH）计数器和使用内反射切伦科夫光（DIRC）检测的计数器。RICH原理使用从辐射器发射到膨胀体积中的光来对切伦科夫锥成像，而DIRC原理依赖于辐射器本身的光学性质来将光内部传播到光子检测阵列。后一种技术也研究了能量和飞行时间的测量。英国核物理界参与了三个令人兴奋的新探测器开发，用于强相互作用的精确研究，PANDA圆盘DIRC，CLAS 12探测器的升级与气凝胶RICH和未来电子-离子对撞机EIC的DIRC探测器的概念研究。格拉斯哥大学的核物理小组正在领导PANDA盘DIRC的开发以及CLAS 12 RICH的光子探测系统的开发和测试。这些探测器系统依赖于分段的、高速率和高粒度的、具有单光子能力的探测设备。所有探测器系统都必须在强磁场内或附近工作。他们的光子探测系统需要一个大的填充分数和紧凑的几何形状。我们目前和以前的测试表明，现有的商业解决方案都不符合核物理和粒子物理中未来切伦科夫计数器的标准。我们计划与英国的研究和工业合作伙伴Kelvin Nanotechnology、Kelvin/Rutherford实验室和Photek一起开发和测试新一代光子探测器。该项目包括增益、均匀性、速率依赖性、时间分辨率、阴极寿命和光子探测效率的测试。这些研究将通过对探测器本身及其应用性能的模拟研究来补充。该性能将在Photek和格拉斯哥大学的实验室进行测试，并在斯特拉斯克莱德大学、GSI和CERN使用现有的切伦科夫原型进行电子和强子束测试。该项目的主要研究人员正在领导欧洲联合研究活动“切伦科夫成像”，该活动补充了拟议的研究，例如在德国Juelich的COSY的应用。此外，我们正在密切合作，与英国机构参与的火炬项目，提出升级的LHCb探测器的基础上适应PANDA光盘DIRC设计的飞行时间测量，和ATLAS前进物理group.The属性的光子探测系统的调查是极大的兴趣超出了基础核和粒子物理研究的边界。它在未来医学成像模式（如飞行时间PET或PET/MRI融合）中的应用是显而易见的。不太明显，但可能同样重要的是，它可以大大提高目前在细胞研究和其他生命科学应用中研究时间分辨荧光现象的能力。主要研究者和他的小组目前正在与Beatson癌症研究所合作，对这些应用进行试点研究。

Future experiments in nuclear, hadronic and particle physics rely on the identification and complete, precise determination of the four-momentum vector of all reaction products. Imaging Cherenkov detector are an invaluable tool in providing this information. Charged particle traversing a dielectric medium with a speed greater than the speed of light inside the medium emit a come of Cherenkov radiations. The opening angle of this cone is (for a given refractive index of the radiator medium) a measure of the particles's velocity. This provides, combined with an independent moment measurement, a powerful method to infer the mass of the particle in question. Imaging Cherenkov detectors current under development can be categories in two classes, classical Ring Imaging CHerenkov (RICH) counters and counters using the Detection of Internally Reflected Cherenkov light (DIRC). The RICH principle uses the light emitted from the radiator into an expansion volume to image the Cherenkov cone, while the DIRC principle relies on the optical properties of the radiator itself to propagate the light internally towards a photon detection array. The latter technique is also studied for energy and time-of-flight measurements. The UK nuclear physics community is involved in three exciting new detector developments for precision studies of the strong interaction, the PANDA disc DIRC, the upgrade of the CLAS 12 detector with an Aerogel RICH and conceptual studies for the DIRC detector at a future electron-ion collider EIC. The nuclear physics group at the University of Glasgow is leading the development of the PANDA disc DIRC and the development and testing of the photon detection system for the CLAS 12 RICH.These detector systems rely on segmented, high rate and high granularity, single photon capable detection devices. All detector systems will have to operate within or in the vicinity of a strong magnetic field. Their photon detection systems require a large filling fraction and a compact geometry. Our current and previous tests demonstrated that none of the available commercial solutions fulfil the criteria for future Cherenkov counters in nuclear and particle physics. We propose to develop and test a new generation of photon detectors together with research and industrial partners in the UK, Kelvin Nanotechnology, Kelvin/Rutherford laboratory and Photek.The project comprised test of gain, homogeneity, rate dependence, time resolution, cathode lifetime and photon detection efficiency. These studies will be complemented by simulation studies of the detectors themselves and their properties in applications. The performance will be tested in laboratories at Photek and the University of Glasgow and by using existing Cherenkov prototypes in electron and hadron beams at the University of Strathclyde, GSI and CERN.The principal investigator of this project is leading the European Joint Research Activity "CherenkovImaging" which complements the proposed research e.g. for applications at COSY, Juelich, Germany. Furthermore we are closely collaborating with UK institutions involved in the TORCH project, a proposed upgrade of the LHCb detector based on adapting the PANDA disc DIRC design to time-of-flight measurements, and the ATLAS Forward Physics group.The properties of the photon detection system investigated are of great interest beyond the boundaries of fundamental nuclear and particle physics research. Its application in future medical imaging modalities like Time-of-Flight PET or PET/MRI fusion, is obvious. Less obvious, but potentially equally important, it could greatly enhance the current capabilities of studying time resolved fluorescence phenomena in cell research and other life-science applications. THe principle investigator and his group are currently conducting a pilot study into these applications in collaboration with the Beatson Institute for Cancer Research.