MRI: Development of a High Resolution Neutron Detector for Decay and Reaction Studies with Exotic Nuclei

该奖项的科学重点是通过研究通过特定过程产生并发射中子的核状态来解释宇宙中元素的形成。该研究将使用一种新的多探测器阵列n5D来完成，该阵列将由该奖项开发。这个新的探测器将使科学家能够回答与快中子捕获过程有关的问题，这是造成近一半比铁重的元素的原因，并研究富含中子的同位素的性质。准确有效地测量中子能量是核光谱学中最困难的任务之一。随着新的探测器阵列的高精度和检测效率，科学家们将能够研究外来核上的β -延迟中子发射，其中β -强度分布的知识对于预测远离稳定的核的核寿命是必要的。这个核磁共振项目将培养未来的科学家，他们将负责该阵列的大部分测试和操作。该项目将利用电子和探测器材料的最新发展，提供一种中子探测器，不仅用于基础科学，还用于国家安全、医疗、工业应用和空间探索。该项目将开发一种具有独特跟踪能力的新型中子探测器阵列。该n5D探测器阵列将服务于衰变和反应实验，这些实验需要在100 keV到10 MeV的能量范围内检测中子。在n5D中，将使用飞行时间（TOF）技术检测中子。该项目的新颖之处在于高中子能量分辨率，这将通过跟踪中子在探测器材料中的相互作用来实现。与伽马射线探测不同，TOF技术不需要对探测器中沉积的全部能量进行登记；标记/跟踪交互点就足够了。因此，跟踪将克服典型TOF中子探测器的主要限制，即最大化效率所需的探测器厚度会降低中子能量分辨率。将使用明亮的中子-伽玛鉴别塑料闪烁体。它们将使实验能够在限制伽马射线背景水平的情况下进行，并将提高信噪比。闪烁读数将使用紧凑的分段光电倍增管来实现，这有助于跟踪所需的高探测器粒度，这是该领域的关键进步。数字电子器件将用于信号处理，提供定时和中子-伽马辨别，以及未来实现新型闪烁体或光读出传感器所需的灵活性。一个由40-50个模块组成的阵列将用于衰变和反应实验。田纳西大学诺克斯维尔分校/田纳西理工大学团队将利用其在中子探测器开发和数字信号处理方面的专业知识。该项目的关键要素是优化单探测器模块的性能和有效的生产成本，使该阵列易于扩展，可以与世界各地主要研究中心的大型系统一起工作。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 scientific focus of this award is to explain the formation of elements in the Universe by studying nuclear states that are produced through specific processes and emit neutrons. That study will be done with a new multi-detector array, n5D, which will be developed with this award. This new detector will allow scientists to answer questions related to the rapid neutron capture process, which is responsible for nearly half the elements heavier than iron, and to study the properties of very neutron rich isotopes. Measuring neutron energies precisely and efficiently is one of the most difficult tasks in nuclear spectroscopy. With the high accuracy and detection efficiency of the new detector array, scientists will be able to study beta-delayed neutron emission on exotic nuclei, where knowledge of the beta strength distribution is necessary to predict nuclear lifetimes for nuclei far from stability. This MRI project will train future scientists who will conduct the bulk of the testing and operation of the array. The project will leverage recent developments in electronics and detector materials to provide a neutron detector for use not only in fundamental science but also in national security, medical, and industrial applications, and space exploration.This project will develop a new neutron detector array with unique tracking capabilities. This n5D detector array will serve decay and reaction experiments, which require neutron detection in the 100 keV to 10 MeV range of energies. In n5D, neutrons will be detected using the time-of-flight (TOF) technique. The novelty of the project is the high neutron energy resolution, which will be achieved by through tracking the interactions of the neutron as it travels through the detector material. Unlike in the case of gamma ray detection, the TOF technique does not require registration of the full energy deposited in the detector; tagging/tracking the interaction points is sufficient. The tracking will thus overcome the main limitation of a typical TOF neutron detector, where the detector thickness required to maximize efficiency degrades the neutron energy resolution. Bright neutron-gamma-discriminating plastic scintillators will be used. They will enable experiments with otherwise limiting levels of gamma-ray background and will improve the signal to noise ratio. Scintillation readouts will be achieved using compact segmented photomultipliers facilitating the high detector granularity required for tracking, a key advancement in this field. Digital electronics will be implemented for signal processing providing the timing and neutron-gamma discrimination as well as the flexibility needed to implement new scintillators or light readout sensors in the future. An array of about 40-50 modules will be constructed for decay and reactions experiments. The University of Tennessee, Knoxville/Tennessee Tech University team will build upon its expertise in neutron detector development and digital signal processing. Key elements of the project are optimization of single-detector module performance and an efficient production cost, such that the array is easily scalable to work with large systems at major research centers throughout the world.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.