A First Measurement of the Coherent Elastic Neutrino-Nucleus Scattering Cross Section

现在，对基本粒子性质进行精确的实验测试是一种成熟的方法，可以在我们目前的物理知识之外寻找新的自然规律。粒子相互作用的标准模型描述了已知的基本粒子及其相互作用。然而，标准模型最简单的形式并不包括中微子的非零质量，这一点现在已经有了实验证明。这需要继续努力改进标准模型，并进一步加深我们对中微子性质和相互作用的了解。中微子从原子核中散射，使原子核保持完整，这是大约40年前首次描述的，但仍然缺乏实验证明。按照这里的计划，对这种中微子相互作用模式的准确测量将提供几个仍然不受约束的中微子性质的句柄，有助于制定标准模型的改进。这项研究将使用钠掺杂的碘化铯闪烁体作为探测相干弹性中微子-核散射的有利目标，利用橡树岭国家实验室散裂中子源设施产生的强烈中微子产量。这种材料对低能核反冲的响应，就像这一过程预期的那样，已经得到了表征，并使用一个2公斤的低本底原型晶体在专用辐射屏蔽中进行了全面的可行性测试。在这些研究的基础上，计划中的14公斤探测器预计每年将测量这种中微子相互作用模式下的大约550次事件。在获奖期间，还将研究在核物理和超新星探测中感兴趣的铅-208上仍未测量的产生带电中微子与中微子的相互作用。

Precise experimental tests of fundamental particle properties are now a well-established way to search for new laws of nature beyond our current physical knowledge. The Standard Model of particle interactions describes known fundamental particles and their interactions. However, the Standard Model in its simplest form does not include a nonzero mass of the neutrino, for which there is now experimental proof. This calls for a continued effort to improve the Standard Model, and to further our knowledge of neutrino properties and interactions. Neutrino scattering from the nucleus, which leaves the nucleus intact, was first described some forty years ago, but still lacks an experimental demonstration. An accurate measurement of this mode of neutrino interaction, as planned here, will provide a handle on several still unconstrained neutrino properties, contributing information that helps to formulate refinements to the Standard Model.This research will use sodium-doped cesium iodide scintillators as an advantageous target for the detection of Coherent Elastic Neutrino-Nucleus Scattering, exploiting the intense neutrino yield from the Spallation Neutron Source facility at Oak Ridge National Laboratory. The response of this material to low-energy nuclear recoils, like those expected from this process, has been characterized and a full feasibility test has been performed using a 2 kg low-background prototype crystal in a dedicated radiation shield. Based on these studies, a planned 14 kg detector is expected to measure approximately 550 events per year from this mode of neutrino interaction. The still unmeasured neutron-generating charged-current neutrino interaction on Pb-208, of interest in nuclear physics and for supernova detection, will also be studied during the period of the award.