Development of micro-thermal dividers for hybrid pixel detectors coupling cryogenic HPGe sensors and room temperature ASICs.

该项目提出了一种新的、未经证实的颠覆性技术，使高纯度锗（HPGe）传感器与现有的室温专用集成电路（asic）在混合像素探测器中的应用成为可能。本文建议设计和测试一种微热分割器，将傅立叶热传导定律设定的物理要求转化为利用微制造和微加工工艺以及微电子互连技术提供的功能的工程解决方案。微热分压器将控制一个具有挑战性的δ T ~130°C超过100 μ m。本项目研制的混合像素探测器将主要应用于光子科学领域。在这里，混合像素探测器通过结合直接光子探测、小像素尺寸、快速读出和每个像素的复杂信号处理电路，为x射线探测提供高性能解决方案。对于20kev以上的x射线检测，需要不同于硅的高z传感器来实现高量子效率，但许多高z材料如GaAs， CdTe和CdZnTe经常遭受不利的材料性能或不均匀性。值得注意的是，HPGe晶体提供了有利的晶体特性和材料纯度的独特组合，转化为高，均匀的检测效率和优异的能量分辨率，在大面积（晶圆直径~90mm）。目前，在混合像素探测器中部署HPGe传感器受到传感器低温要求的限制，这通常与低温asic的发展有关。这些都是小众、复杂和昂贵的开发项目。相反，我们建议通过研究微技术的有效性来取代低温asic对高能辐射探测仪器的需求，从而改变现有思想的范式。为了实现这一点，将在传感器和ASIC之间插入一个微热分压器。它将传感器与ASIC产生的热量隔离，并将在传感器下方提供直接冷却。该项目的高风险和投机方面涉及在短距离（100 μ m）内管理高温梯度（~130℃），同时保持设备的优异电气性能和机械稳定性。本次竞标的目标是建立一个功能原型，展示该技术的可行性（概念验证），并为下一次迭代生成基础工作，届时将建立一个完整的工程设备。该项目的主要目的是使英国在为旗舰同步加速器和自由电子激光实验建立下一代混合像素探测器方面处于领导地位。我们希望开发一种创新技术来操作室温asic的HPGe传感器。核医学成像应用（检测伽马射线）和x射线光谱分子成像等高端应用也将受益于这一技术进步，这有可能提高医疗保健诊断的质量。这个建议的解决方案有一个节能方面。与同等的低温ASIC相比，室温ASIC的工作温度需要更少的冷却功率。这将有助于减少碳足迹，同时开发基于HPGe传感器的尖端仪器。通过微热分压器将卫星操作与真空热管理/能源效率进行类比，可以为空间仪器提供更有效的热控制系统。最后，微热分压器的研发与量子计算领域具有协同效应。在这里，我们的方法可用于开发具有多个温度阶段的低温环境中量子-经典界面的新封装解决方案。例如，这可能有利于基于超导量子比特的量子计算机。

This project is proposing a new, unproven and disruptive technology to enable the application of High Purity germanium (HPGe) sensors with existing room temperature Application Specific Integrated Circuits (ASICs) in hybrid pixel detectors. It is proposed to design and test a micro-thermal divider translating the physics requirements set by the Fourier's Law of heat conduction, into an engineered solution exploiting the capabilities offered by micro-fabrication and micro-machining processes, and by micro-electronics interconnection techniques. The micro-thermal divider will control a challenging delta T of ~130deg C over few 100's um. The hybrid pixel detectors prototyped in this project will target mainly applications in photon-science. Here, hybrid pixel detectors provide high performance solutions for X-ray detection by combining direct photon detection, small pixel size, fast readout and sophisticated signal processing circuitry in each pixel. For X-ray detection above 20 keV, high-Z sensors different than silicon are required to achieve high quantum efficiency, but many high-Z materials such as GaAs, CdTe and CdZnTe often suffer from unfavourable material properties or nonuniformities. Remarkably, HPGe crystals provide a unique combination of favourable crystal properties and material purity that translates into a high, uniform detection efficiency and an excellent energy resolution, over a large area (wafers ~90mm dia.). The deployment of HPGe sensors in hybrid pixel detectors is currently limited by the cryogenic requirements of the sensors, which is usually linked to the development of cryogenic ASICs. These are niche, complex and costly developments. Instead, we propose a shift of paradigm in the existing thought by studying the effectiveness of micro-technologies to replace the need of cryogenic ASICs for high-energy radiation detection instrumentation. To achieve this, a micro-thermal divider will be inserted between the sensor and the ASIC. It will insulate the sensor from the heat generated by the ASIC, and it will provide direct cooling underneath the sensor.The high-risk and speculative aspect of the project is related to managing a high temperature gradient (~130deg C) over a short distance (100's um), while maintaining an excellent electrical performance and mechanical stability of the device. The ambition of this bid is to build a functional prototype demonstrating the feasibility of the technology (proof of concept), and generating foundation work for the next iteration, where a fully engineered device will be built.The main aim of the project is to position the UK in a leadership role to build the next generation of hybrid pixel detectors for flagship synchrotron and free electron laser experiments. We want to develop an innovative technique to operate HPGe sensors with room temperature ASICs. High-end applications like nuclear medical imaging applications (detecting gamma-rays) and X-rays spectral molecular imaging would also be beneficiaries of this technological progress, which has the potential to improve the quality of diagnostics in healthcare. There is an energy saving aspect related to this proposed solution. The operating temperature of a room temperature ASIC would require less cooling power than an equivalent cryogenic ASIC. This would contribute to reduce the carbon footprint while developing cutting edge instrumentation based on HPGe sensors. The analogy of satellite operations with in-vacuum thermal management/energy efficiency via micro thermal-dividers could lead to more efficient thermal control systems for space instrumentation. Finally, R&D on a micro thermal-divider has synergies with the field of quantum computing. Here, our approach could be used to develop new packaging solutions for the quantum-to-classical interface in a cryogenic environment with multiple temperature stages. For instance, this could benefit quantum computers based on superconducting qubits.