Low-Threshold Modular Detectors for Coherent Elastic Neutrino-Nucleus Scattering

该研发奖的目标是开发用于相干弹性中微子核散射（CEvNS）测量优化的过渡边缘传感器（TES）探测器，其低能量阈值比用于初始CEvNS测量的CsI探测器低两个数量级。这些探测器将在低反冲能量下打开一个新的窗口，以研究中微子物理学中尚未被充分探索的相对较新的通道。通过测量来自反应堆的中微子光谱，并将其与标准模型预测进行比较，我们获得了对超出标准模型的物理敏感性，包括1)异常中微子磁矩，2)中微子的非标准相互作用（NSI），以及3)中微子与超出标准模型的新粒子耦合。与此同时，他们将研究反应堆反中微子通量的低能端，这是反β衰变探测器无法到达的，并寻找可能存在的无菌中微子，这种中微子被假设存在，但从未被发现。为了实现这一目标，有四个目标：(1)对基于低阈值tes的CEvNS实验进行详细的建模和优化，重点关注探测器的性能、背景和科学范围；(2)基于(1)的结果制作几个原型探测器；(3)测试这些探测器并将其性能与模型进行比较；(4)培养新一代中微子实验物理学家。这项工作具有广泛的影响，超出了中微子物理学。TES探测器在宇宙学、天文学、工业和国防领域都有应用。这项活动将有助于本科生、研究生和博士后研究人员的培训，通过参加西北大学的夏季研究机会计划（SROP），继续该组织对代表性不足群体的本科生进行指导的承诺。该小组将评估TES设计，以优化核反应堆CEvNS实验的科学输出。给定探测器上的中微子通量，他们将考虑TES设备的物理特性、目标材料和每个探测器的质量、读出复用架构和这些参数的可实现质量、探测器封装和在低温系统中的安装、背景、屏蔽和校准。他们将根据优化研究的结果在标准硅片上制造多个TES传感器。费米实验室的西北实验地下基地（NEXUS）将用于测试这些原型探测器，并将其性能与模型进行比较。校准将使用光学和x射线源以及专用中子束和后备探测器阵列进行，以准确报告对低能核反冲的响应。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The goal of this R&D award is to develop Transition-Edge Sensor (TES) detectors optimized for measurements of Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) with low-energy thresholds two orders of magnitude lower than the CsI detectors used for the initial CEvNS measurement. These detectors will open a new window at low-recoil energies to study this relatively new channel in neutrino physics that has yet to be fully explored. By measuring the neutrino spectrum from a reactor, and comparing it to the standard model predictions, we gain sensitivity to physics beyond the Standard Model in scenarios including 1) an anomalous neutrino magnetic moment, 2) Non-Standard Interactions (NSI) of neutrinos, and 3) neutrinos coupling to new particles beyond the Standard Model. At the same time, they will enable a study of the low energy end of the reactor antineutrino flux that is inaccessible to inverse-beta-decay detectors and a search for possible sterile neutrinos, which have been postulated to exist but have never been seen. In pursuit of this goal, there are four objectives: (1) perform a detailed study to model and optimize a low-threshold TES-based CEvNS experiment focusing on detector performance, backgrounds, and science reach, (2) fabricate several prototype detectors based on the outcome of (1), (3) test these detectors and compare their performance to the models, and (4) train a new generation of neutrino experimental physicists. The work has a broad impact that extends beyond neutrino physics. TES detectors have applications in cosmology, astronomy, industry, and defense. This activity will contribute to the training of undergraduate and graduate students and postdoctoral researchers, continuing the group’s commitment to mentoring undergraduates from underrepresented groups by participating in the Summer Research Opportunities Program (SROP) at Northwestern.The group will evaluate TES designs for optimizing the science output of a CEvNS experiment at a nuclear reactor. Given a neutrino flux at the detector, they will consider the TES device physics, target materials and mass per detector, readout multiplexing architectures and achievable mass with these parameters, detector packaging and installation in a cryogenic system, backgrounds, shielding, and calibration. They will fabricate several TES sensors on standard silicon wafers based on the outcomes of the optimization study. The Northwestern EXperimental Underground Site (NEXUS) at Fermilab will be used to test these prototype detectors and compare their performance to their models. Calibrations will be performed with optical and X-ray sources and a dedicated neutron beam and backing detector array to accurately report the response to low-energy nuclear recoils.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.