Collaborative Research: Equipment: MRI Consortium: Track 2 Development of a Next Generation Fast Neutron Detector

对富含中子的原子核的研究可以揭示质子和中子如何在原子核内相互作用的效应。它们在宇宙中元素的形成中起着重要作用，并帮助科学家了解原子的核心是如何形成的。研究这些处于稳定边缘的原子核的方法之一是测量它们的分裂产物，其中包括不需要将较小的原子核聚集在一起的中子。中子的探测是具有挑战性的，因为它们不带电，只与原子的核核心相互作用。该合同将支持基于塑料闪烁体的模块化阵列的开发、建造和调试，用于检测快速中子（在光速的三分之一到二分之一之间）。与现有的中子探测器相比，新的探测器阵列将大大提高我们确定中子位置的精确度，因为它将利用最先进的光电传感器，从而使核结构测量具有更高的精度。探测器模块将在很大程度上在七个参与的本科院校建造和测试，使本科生能够学习关键的技术技能，并以有意义的方式为核物理研究作出贡献。闪烁探测器，即测量由亚原子粒子在探测器内相互作用产生的闪烁光的探测器，广泛应用于研究，工业和医学成像，因此这些技能可以应用于许多关键领域。当代快中子探测器使用传统的探测器配置，即由一对光倍增管（pmt）读出的长塑料闪烁体条。中子相互作用的位置由探测器杆两端各PMT测得的信号的时间差和探测器杆被击中的位置推断出来。这种新型探测器采用硅光倍增器（SiPMs）阵列，采用不同的方法收集闪烁光，克服了当前设计的局限性，提高了快中子探测的位置分辨率。这也允许平铺设计，提供更大的灵活性来调整阵列的活动区域，以满足特定的实验需要。除氧以外元素中中子非束缚态的恒定质谱需要这样一个分辨率更高的实验装置。当你移动到更重的非束缚系统时，你将面对更高的密度水平。要在重建的衰变能谱中解决这些问题，需要更高的动量（因此也是位置）分辨率。高位置分辨率还提高了对双散射事件的识别，并允许使用在稀有同位素光束设施（如稀有同位素光束设施（FRIB））中可用的更高的光束能量。完成后的仪器将服务于广泛的FRIB用户群体，并能够以FRIB光束提供的更重和更奇特的同位素所需的分辨率进行不变质量测量。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 study of neutron-rich atomic nuclei can reveal effects about how protons and neutrons interact inside nuclei. These play an important role in the formation of the elements in the universe and help scientists understand how the nuclear core of atoms form. One of the ways to investigate these nuclei at the edge of stability is to measure their breakup products, which includes the neutrons that are not needed to hold the smaller nuclei together. The detection of neutrons is challenging because they have no charge and only interact with the nuclear core of atoms. This award will support the development, building, and commissioning of a modular array based on plastic scintillator for the detection of fast (between one third and one half the speed of light) neutrons. The new detector array will significantly improve how precisely we can determine the neutrons’ position compared to current neutron detectors because it will make use of state-of-the-art photo-sensors, and as a result enable nuclear structure measurements with superior precision. The detector modules will be built and tested to a large extent at the seven participating undergraduate institutions, allowing undergraduate students to learn key technical skills and to contribute to nuclear physics research in a meaningful way. Scintillation detectors, i.e. detectors that measure the scintillation light that stems from subatomic particles interacting within the detector, are widely employed in research, industry, and medical imaging, so these skills can be applied in many crucial fields.Contemporary fast neutron detectors use conventional detector configurations of long plastic scintillator bars read out by pairs of photo-multiplier tubes (PMTs). The position of the neutron interaction is deduced from the time difference of the signals measured by each PMT at opposite ends of the detector bar, and from which detector bar has been hit. A different approach to scintillation-light collection is pursued in this new detector using arrays of Silicon Photo-Multipliers (SiPMs), overcoming the limitations of current designs and resulting in improved position resolution for fast neutron detection. This also allows a tiled design that offers much more flexibility in adjusting the active area of the array to specific experiment needs. Invariant-mass spectroscopy of neutron-unbound states in elements beyond oxygen requires such an experimental setup with improved resolution. As one moves to heavier unbound systems one faces higher level densities. To resolve these in the reconstructed decay energy spectrum requires higher momentum (and thus position) resolution. A high position resolution also improves the discrimination of double-scattered events and allows the use of higher beam energies that are available at the rare-isotope beam facilities such as the Facility for Rare Isotope Beams (FRIB). The completed instrument will serve the broad FRIB user community and enable invariant mass measurements at the resolution that is required for heavier and more exotic isotopes that are available with FRIB beams.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.