Development of SiPM-based spectrometers for the UCNtau and UCNA+ experiments

自由中子辐射衰变成质子、电子和反中微子。这一过程发生的速度和抛射粒子的方向，由弱核力的参数决定。对这些参数的精确研究为了解支配我们宇宙的基本物理学提供了一个窗口，并可以识别新的物理学。未来实验的目标是足够灵敏地探测到目前不属于力和粒子标准模型的新物理。为了提高这些实验的灵敏度，必须将新的现代技术和技术融入到实验方法中。该奖项将支持基于硅光电倍增管的中子和电子探测器的研究，这些探测器将减少以前迭代的中子衰变实验中的系统不确定性。该项目将为本科生研究人员提供基本的动手技能培训，使他们为国家STEM劳动力做好准备。与洛斯阿拉莫斯国家实验室的超冷中子物理小组合作，这项研究将能够更精确地测量中子寿命，β不对称参数‘A’，并对中子的电偶极矩进行新的搜索。在这个项目中概述了三个实验目标。首先，为UCNA+实验提供一个基于硅光电倍增管的闪烁探测器，用于测量0.2%的A。该探测器将消除UCNA中使用的多线正比计数器，该计数器是后向散射和能量损失系统学的来源。这项技术将使UCNtau实验中用于高速率计数的类似探测器方案成为可能。第二，提供中子飞行时间能谱仪，用于在线评估超冷中子速度谱，这是理解LANL所有实验中的系统效应所必需的。最后，为LANL超冷中子源提供一种低浓缩铀插件的设计，能够将产量提高四倍。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The free neutron radioactively decays into a proton, electron, and anti-neutrino. The rate at which this process occurs, and the direction of the ejected particles, is determined by parameters of the weak nuclear force. Precision studies of these parameters provide a window into the fundamental physics governing our universe and can identify new physics. The goal of future experiments is to be sufficiently sensitive to detect new physics that is not currently part of the Standard Model of Forces and Particles. To increase the sensitivity of these experiments new modern technologies and techniques must be integrated into the experimental methods. This award will support the investigation of Silicon Photomultiplier based neutron and electron detectors that will mitigate systematic uncertainties in previous iterations of neutron decay experiments. The project will provide undergraduate researchers with essential hands-on training in skills that will prepare them for the national STEM workforce. In collaboration with the ultracold neutron physics group at Los Alamos National Laboratory this research will enable higher precision measurements of the neutron lifetime, the beta-asymmetry parameter ‘A’, and a new search for the neutron’s electric dipole moment. Three experimental goals are outlined in this project. First, provide a silicon photomultiplier-based scintillation detector for a 0.2% measurements of ‘A’ for the UCNA+ experiment. The detector will eliminate the multi-wire proportional counter used in UCNA that was the source of backscattering and energy loss systematics. This technology will enable a similar detector scheme for high rate counting in the UCNtau experiment. Second, provide neutron time of flight spectrometers for online assess of the ultracold neutron velocity spectrum which is essential for understanding systematic effects in all the experiments hosted by LANL. Finally, provide a design of a lightly enriched uranium insert for the LANL ultracold neutron source capable increasing the production by a factor of four.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.