A COHERENT Next Step: Precision Measurement of CENNS Using PPC Germanium Detectors at the SNS

在所有已知的基本粒子中，中微子因其与其他形式物质相互作用的微小概率而难以检测。通常涉及大型（吨或多吨）探测器。相干中微子-原子核弹性散射（英语：Coherent Neutrino-Nucleus Elastic Scattering，CEnNS）是一种中微子相互作用的机制，早在四十多年前就被预测，直到最近才被COHERENT合作测量到。 通过CEnNS检测中微子的概率比任何其他已知的中微子与物质相互作用的模式都要大得多，但产生的信号很微妙，很难分离。只有通过辐射探测的最新进展，才有可能获得这些信号。CEnNS开辟了使用小型手持设备进行中微子探测的可能性，产生了一些有趣的技术应用。该奖项将促进在COHERENT内研究这种有前途的新型中微子相互作用的下一步工作，资助建造最先进的锗探测器，用于橡树岭国家实验室的Spectron中子源。这些设备将以前所未有的精度测量CEnNS，限制逃逸中微子的许多未知特性，并有助于完善粒子相互作用的基础理论。这些装置的发展的几个方面将适用于它们在核不扩散应用中的计划用途，在这些应用中，可以利用浓缩铀-恩同位素示踪剂来监测核反应堆，防止武器级材料的转移。计划中的CEnNS能谱测量将在信号与背景比、大统计量、对全范围反冲能量的灵敏度以及探测器对核反冲反应的详细了解的最佳条件下进行。后者将通过过去，正在进行的，和计划的测量的锗淬火因子的CEnNS引起的核反冲，下至亚千电子伏的能量。从这个新的CEnNS测量中预期的适度不确定性将允许与标准模型（SM）预测进行非常精确的比较。在粒子物理学的一些活跃的研究领域中，目前的实验灵敏度的显著提高将来自于这种比较：例如，中微子电磁特性的研究，粒子物理学标准模型扩展预测的非标准耦合，暗物质模型的测试，以及对第四个无菌中微子的改进灵敏度，仅举几例。该奖项反映了NSF的法定使命，并且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。

Of all known elementary particles, neutrinos stand out for the difficulty involved in their detection, a result of their tiny probability of interaction with other forms of matter. Large (ton or multi-ton) detectors are typically involved. Coherent Neutrino-Nucleus Elastic Scattering (CEnNS) is a mechanism of neutrino interaction predicted more than four decades ago, and only recently measured by the COHERENT collaboration. The probability of neutrino detection via CEnNS is much larger than for any other known mode of neutrino interaction with matter, but the signals generated are subtle and hard to isolate. It is only through recent advances in radiation detection that it has become possible to access these signals. CEnNS opens up the possibility of employing small, handheld devices for neutrino detection, generating some interesting technological applications. This award will facilitate a next step in the investigation of this promising new type of neutrino interaction within COHERENT, funding the construction of state-of-the-art germanium detectors to be used at the Spallation Neutron Source at the Oak Ridge National Laboratory. The devices will measure CEnNS with an unprecedented precision, constraining the many still unknown properties of the evasive neutrino, and contributing to a refinement of the underlaying theories of particle interactions. Several aspects of the development of these devices will apply to their planned use in nuclear non-proliferation applications, where CEnNS can be exploited to monitor nuclear reactors against diversion of weapons-grade material. The planned measurement of the CEnNS energy spectrum will be performed in optimal conditions of signal-to-background ratio, large statistics, sensitivity to the full range of recoil energies, and detailed knowledge of detector response to nuclear recoils. The latter will be achieved through past, ongoing, and planned measurements of the germanium quenching factor for CEnNS-induced nuclear recoils, down to sub-keV energies. The modest uncertainties expected from this new CEnNS measurement will allow a very precise comparison to Standard Model (SM) predictions. A significant improvement of the present experimental sensitivity in a number of active areas of research in particle physics will result from this comparison: for instance, the study of electromagnetic properties of neutrinos, their non-standard couplings predicted by extensions of the Standard Model of particle physics, tests of dark matter models, and an improved sensitivity to a fourth sterile neutrino, to name a few.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.