Improving the Understanding of Gadolinium for use in Neutron Detectors

钆具有非常高的中子俘获截面，特别是同位素Gd-155和Gd-157，并且在发射伽马级联时产生非常高的能量（~8MeV）。然而，这个衰变模型还没有被很好地理解，所以我们希望通过计算和实验方法来改进这个模型。我们希望为热中子捕获的钆机制建立一个良好的模型；这种改进的理解将通过事件识别和背景辨别导致更好的中子探测。采用钆（Gd）作为中子捕获剂的中子探测器可以通过提高对Gd上中子捕获的后续伽马级联的理解来增强。这将开辟一个新的发展领域，其中中子有可能被（部分）标记，从而产生更好的背景辨别。这在大面积探测器中特别有用，其中闪烁体或光传感器本身的固有辐射是一个大的背景源，可以实现新的部署场景。Gd具有极大的热中子俘获截面，仅次于氙的俘获截面。Gd上的中子捕获具有8兆电子伏的q值，导致相关的伽马射线级联。Gd（n, γ）相互作用已经被研究过，并且积分谱是已知的，但是单个的衰变模式还没有被测量。4- γ模式占主导地位，尽管它们没有被测量为离散能量，并且不知道4- γ的能量是否等于衰变的q值（8兆电子伏）。考虑到可用的能量，可能会有多个亚兆电子伏级联。博士将计算和测量伽马谱，从而确定每个检测到的事件中缺少什么，并允许对事件进行标记。

Gadolinium has a very high neutron capture cross section, particularly isotopes Gd-155 and Gd-157 and produces a very high energy upon emission of a gamma cascade (~8MeV). However, this model for decay is not well understood, so we hope to improve this model via both computational and experimental methods. We hope to achieve a good model for the gadolinium mechanism of thermal neutron capture; this improved understanding will lead to better neutron detection via event identification and background discrimination. Neutron detectors that employ Gadolinium (Gd) as the neutron capture agent can be enhanced by improving the understanding of the subsequent gamma cascade of the neutron capture on Gd. This would open up a new area of development where the neutron has the potential to be (partially) tagged, resulting in better background discrimination. This is particularly useful in large area detectors where intrinsic radiation in the scintillator or the photo-sensor itself is a large source of background, enabling new deployment scenarios. Gd has an extremely large thermal neutron capture cross-section, second only to the capture cross-section of Xenon. The neutron capture on Gd has a Q-value of 8-MeV resulting in an associated gamma-ray cascade.Gd(n, gamma) interactions have been studied and the integrated spectrum is known, but the individual decay modes have not been measured. The 4-gamma mode is dominant, although these are not measured to be discrete energies and it is not known if the energy of the four gammas is equal to the Q-value of the decay (8 MeV). Given the available energy there is likely to be multiple sub-MeV cascades. The PhD will calculate and measure the gamma spectrum, hence determining what is missing in each detected event and allowing the events to be tagged.