Imaging and location of fast neutron emissions by real-time time-of-flight

拟议的研究包括研究一种不同的方式，利用中子来消除核环境。拟议的项目是由兰开斯特大学工程系领导的一项合作，并获得了卡勒姆聚变能中心的专业知识。中子约占构成我们周围物质核的亚原子粒子的一半。它们不带电，因此与其他常见形式的辐射（如伽马射线、质子、电子等）相比，不会与环境发生强烈的相互作用。然而，它们是反应堆和粒子加速器中核反应的结果，因此存在于与核技术真正的全球应用（如核能、推进、防止核扩散和核医学。幸运的是，由于快中子不像伽马射线那样以光速传播，因此根据它们传播一段距离所需的时间，它们很容易与伽马射线分离。这种方法被广泛地称为“飞行时间”（ToF）。基于它们的飞行时间来利用快中子和伽马射线的速度之间的差异目前仅限于相当深奥的应用，例如分别在NPL和nTOF（CERN）的标准实验室和粒子加速器设施中找到中子的能量。虽然这种应用在辐射计量学的特定领域中非常重要，但该技术在推断放射性物质的位置以及工业和医学中辐射发射的分布方面的更广泛应用尚未实现。该提案的重点是颠倒上面提到的广泛接受的ToF方法（通常的目标是估计中子的能量），看看我们是否可以在它们产生的环境中定位和成像快中子的起源。该提案的重点假设是，根据我们对典型感兴趣环境（如动力反应堆和医疗设施）中中子能量分布的先验知识，确定是否有可能获得从检测地点到中子发射地点的距离估计。然后，这些信息可能被用来定位和潜在的中子发射系统或物质的图像;以前没有探索过的飞行时间方法的工程使用。因此，这项研究将确定是否可以使用数字和实时执行的飞行时间来指示位置并可能对中子辐射源进行成像。本研究的主要目标是确定ToF方法是否可以作为一种工程能力应用，在工业和医学中具有一系列潜在的应用。这些措施包括：防止核材料被盗（核保障）、核反应堆特性鉴定、核安全和癌症治疗中使用质子产生的中子场特性鉴定。

The proposed research comprises a study into a different way in which to use neutrons to characterise nuclear environments. The proposed project is a collaboration led by the Department of Engineering at Lancaster University with expertise from the Culham Centre for Fusion Energy. Neutrons make up approximately half of the subatomic particles that constitute the nuclei of matter around us. They are uncharged and therefore do not interact strongly with the environment in comparison with other common forms of radiation such as gamma rays, protons electrons etc. However, they are emitted as a result of nuclear reactions in reactors and particle accelerators and are thus present in many environments associated with truly global applications of nuclear technology such as nuclear power, propulsion, the prevention of nuclear proliferation and nuclear medicine. Fortunately, because fast neutrons do not travel at the speed of light in the same way that gamma rays do, they are readily separated from gamma rays on the basis of how long they take to travel a set distance. This approach is widely referred to as 'time-of-flight' (ToF).Exploiting the difference between the speed of fast neutrons and gamma rays on the basis of their time-of-flight is currently limited to rather esoteric applications such as finding the energy of neutrons at standards laboratories and particle accelerator facilities, for example at NPL and nTOF (CERN), respectively. Whilst this application is very important in the specific field of radiation metrology, wider application of the technique to infer the location of radioactive substances and the distribution of radiation emissions in industry and medicine has not yet been achieved. The focus of this proposal is to invert the widely-accepted ToF approach referred to above (by which the usual objective is to estimate the energy of neutrons) to see if we can locate and image the origin of fast neutrons in environments where they arise. The hypothesis at the focus of this proposal is that, based on our prior knowledge of the energy distribution of neutrons in typical environments of interest (such as power reactors and medical facilities), is to determine whether it is possible to obtain an estimate of the distance from the site of detection to the site of neutron emission. This information might then be used to locate and potentially image a neutron-emitting system or substance; an Engineering use of the time-of-flight method that has not been explored before. This research will thus determine whether time-of-flight, performed digitally and in real-time, can be used to indicate the location and to potentially image a source of neutron radiation. The key objective of this research is to determine whether the ToF approach can be applied as an Engineering capability that will have a range of potential applications in industry and medicine. These include for example: preventing the theft of nuclear materials (nuclear safeguards), nuclear reactor characterisation, nuclear security and the characterisation of neutron fields that result from the use of protons in cancer therapy.