Non-ionizing Backgrounds to Light Dark Matter Searches

暗物质是我们目前物理宇宙模型中的一个基本问题。有压倒性的证据表明，宇宙中85%的物质具有未知的性质。我们只能通过它在星系和星系团等大型结构上的引力印记看到它。因为这个自然界的奥秘是如此基础，研究物质和能量的粒子物理学家优先考虑暗物质的研究。有许多令人兴奋的关于暗物质的新理论，其质量与质子的质量相似，甚至低于质子的质量。质量接近质子质量的暗物质很有趣，因为暗物质和正常物质的数量密度可以通过各种机制联系起来，解释物理学中其他悬而未决的问题。这些低质量的暗物质候选者不会沉积大量的能量，因此需要新的探测器技术来取得重大进展。扰乱脆弱的超导状态所需的微小能量引起了极大的兴趣，因为它使我们能够在这些微小能量下探测自然界的能量，电离探测器能量的千分之一。超导体中的这种低能量跃迁能够在高能量和较低的能量阈值下实现更好的能量分辨率，这正是测试暗物质粒子可能与质子质量相似的假设所需要的特征。对暗物质的研究已经系统地探测、了解并减轻了大多数电离辐射的自然来源，这些辐射的能量接近或高于原子尺度。然而，为了充分利用超导探测器，我们现在需要用非电离辐射来完成对自然的同样理解，特别是理解任何相当于0.001伏或更高的电子能量的自然来源，它可以破坏超导体中的铜对，从而产生准粒子。这是一项雄心勃勃的事业，需要将物理学和材料科学的不同学科结合起来。我建议从CUTE低温恒温器开始，在SuperCDMS计划中用于早期科学，并对低温恒温器内的红外环境进行建模。我将与NIST和加州理工学院在光子探测技术上合作，这将允许在CUTE低温恒温器内对红外光子背景进行建模和基准测试。新型超导电子学与自然辐射源之间的这种关系是应用研究和基础研究的自然融合，随着我们探索暗物质的本质，以及在低温下开发更敏感的量子计算和传感设备，这种关系将不断发展。

Dark matter is one of the fundamental problems in our current model of the physical Universe. There is overwhelming evidence that 85% of the matter in the Universe has an unknown nature. We only see it through its gravitational imprint on large structures such as galaxies and clusters of galaxies. Because this mystery of nature is so fundamental, particle physicists, who study matter and energy, have prioritized dark matter research. There are a number of exciting new theories about dark matter with masses similar to, or even lower than, the mass of the proton. Dark matter with masses near the proton mass are interesting because the number density of dark matter and normal matter could be connected through various mechanisms that explain other outstanding questions in physics. These low-mass dark matter candidates do not deposit a significant amount of energy, so new detector technologies are required to make significant progress. The minute energy required to disturb the fragile superconducting state is of great interest because it allows us to probe for energy in nature at those minute energies, a thousandth of the energy of ionization based detectors. This low energy transition in superconductors enables better energy resolution at high energies and a lower energy threshold, exactly the characteristics required to test the hypothesis that dark matter particles may be similar in mass to the proton. Dark matter searches have systematically detected, understood, and mitigated most of the natural sources of ionizing radiation, with energies near or above the atomic scale. However, to fully exploit superconducting detectors, we now need to accomplish the same understanding of nature with non-ionizing radiation, specifically understanding any natural source of energy equivalent to an electron at 0.001 volts or above which can break cooper pairs in superconductors resulting in quasiparticles. This is an ambitious undertaking and involves bringing together different disciplines of physics and material science. I propose starting with the CUTE cryostat, being used for early science in the SuperCDMS program, and modelling the infrared environment within the cryostat. I will collaborate with NIST and Caltech on photon detection technologies that will allow both modelling and benchmarking of the infrared photon background within the CUTE cryostat. This relationship between new superconducting electronics and natural sources of radiation is a natural convergence in applied and fundamental research, which will grow as we both explore the nature of dark matter, and develop more sensitive quantum computing and sensing devices at low temperature.