Transition-edge sensors: achieving true potential

该提案主要是一个理论项目，旨在解决与一种有前途的低温探测器类型相关的几个最重要的突出问题，超导过渡边缘传感器（TES），它提供了远远超过传统半导体技术的独特能力。在过去的十年中，基于TES的探测器已在暗物质搜索，X射线天体物理学，时间分辨X射线吸收光谱学，量子信息处理，生物传感器，工业材料分析和国土安全等不同领域得到应用。实际仪器需要对速度、线性度、能量分辨率和阵列尺寸进行复杂的优化。然而，缺乏对TES中超导转变的了解限制了我们优化性能和预测新探测器设计行为的能力。在技术广泛发展的时期，目前的TES模型发挥了重要作用。然而，基于经验观察，这些模型缺乏对超导性的基本细节的了解，而超导性决定了过渡，并最终决定了TES的性能。它们不能解释可观测到的能量分辨率，以及最近发现的TES的弱超导性等基本性质。因此，目前用于某些应用的TES检测器的开发路径仍然非常耗时和昂贵，在许多方面都是基于试错。如果能够更好地理解TESs的基本物理特性，预计将取得重大进展，因为这将支持精确和简化的设计过程，从而缩短针对性设计选项的实验周期。该项目旨在基于基本超导理论开发新的TESs电阻转变理论模型。目标是：1.了解TES中的电阻转变机制作为空间非均匀超导系统，模拟电和热波动，这决定了TES微纳量热计的能量分辨率和测辐射热计的噪声性能2。建立了多层TES结构中的非局域能量输运模型，包括能量沉积和下转换的极短时间尺度上的能量逃逸和涨落。通过评估石墨烯和少层氮化硼的潜力，促进下一代高性能TES的开发，以工程化地耦合到热浴和形成电阻过渡。该项目的预期成果是一种新的方法，用于对单个应用的速度、线性度、能量分辨率和阵列尺寸进行复杂的优化。一些例子说明了潜在的影响。将基于TES的软X射线探测器的能量分辨率提高到2 eV以下，将使向欧空局提出的雅典娜X射线使命提案能够研究星系团热气中的湍流，还将使透射电子显微镜（TEM）中X射线荧光信号的化学位移绘图成为可能，从而为工业材料分析开辟令人兴奋的可能性。每个阵列像素数量的增加将导致未来X射线望远镜的有效成像，并且还提供了在新兴同步加速器应用中维持更高通量水平的能力，例如时间分辨X射线光谱学。随着高分辨率X射线光谱设备的几个潜在市场，最值得注意的是同步加速器设备和TEM设备制造商，新公司的出现是一个可能的结果。对于伽马射线和中子光谱学，具有更高能量分辨率的更大的TES探测器阵列意味着更有效和更快的筛选，促进了乏核燃料无损分析和核材料实际探测等领域的评估任务。

SummaryThe proposal is primarily a theoretical project aimed at resolving several of the most important outstanding problems associated with a promising type of cryogenic detector, the superconducting Transition Edge Sensor (TES), which offers unique capabilities far exceeding that of traditional semiconductor technology. Over the past decade TES-based detectors have found application in diverse areas from dark matter searches, X-ray astrophysics, time-resolved X-ray absorption spectroscopy, quantum information processing, biological sensors, industrial material analysis and homeland security. Practical instruments require a complex optimization of speed, linearity, energy resolution and array size. However, lack of understanding of the superconducting transition in TESs limits our ability to optimise performance and predict the behaviour of a new detector designs. The present models of TESs have played an important role during a period of extensive development of technology. However, based on empirical observations the models lack knowledge of the fundamental details of superconductivity, which determine the transition, and ultimately the performance of TESs. They cannot explain the observable energy resolution, and such fundamental properties as recently-discovered weak superconductivity of TESs. As a result, the current development path of TES detector for a certain applications is still very time consuming and costly, being in many aspects based on trial and error. Significant advances are expected if better understanding of the fundamental physics of TESs is achieved, because this would underpin accurate and streamlined design processes, leading to shorter periods of experiments with targeted design options.The project aims to develop new a theoretical model of the resistive transition in TESs based on fundamental superconductivity theory. The objectives are: 1. Understanding the mechanisms of the resistive transition in TESs as spatially inhomogeneous superconducting systems, simulating electrical and thermal fluctuations, which determine the energy resolution of TES micro- and nano- calorimeters and noise performance of bolometers2. Developing a model of non-local energy transport in multilayered TES structures, including energy escape and fluctuations over the extremely short time scale of energy deposition and down-conversion.3. stimulating the development of the next generation of high-performance TESs by evaluating the potential of graphene and few-layer boron nitride for engineering the coupling to a thermal bath and shaping the resistive transitionAn expected outcome of this project is a new approach to complex optimization of speed, linearity, energy resolution and array size for individual applications. A few examples illustrate the potential impact. An improvement of the energy resolution of TES-based soft X-ray detectors below 2 eV will allow the Athena X-ray mission proposal to ESA to study turbulence in the hot gas of clusters of galaxies, and will also allow the mapping of chemical shifts in X-ray fluorescence signals in Transmission Electron Microscopy (TEM), thus opening exciting possibilities for Industrial Materials Analysis. An increase in the number of pixels per array would lead to efficient imaging on a future X-ray telescope, and also provides the ability to sustain higher flux levels in emerging synchrotron applications, such as time-resolved X-ray spectroscopy. With several potential markets for high-resolution X-ray spectroscopy equipment, most notably synchrotron facilities and manufacturers of TEM equipment, the emergence of new companies is a likely consequence. For gamma-ray and neutron spectroscopy, larger arrays of TES detectors with higher energy resolution imply more efficient and faster screening, facilitating assessment tasks in such fields as non-destructive assay of spent nuclear fuel, and the operational detection of nuclear materials.