Mark Selwood

Development of Technologies for a Portable Monosphere Neutron Spectrometer

Lancaster University, Doctor of Philosophy, 2015

Supervisors: S.D. Monk and C.J. Taylor


This work centres upon the creation of a portable means of neutron spectrometry, after concern had been raised for the safety of both human beings and electrical components on-board aircraft, due to the increased levels of cosmic radiation exposure whilst at flight altitude. The work follows on from that previously reported, wherein a device was constructed, which had limited neutron characterisation capabilities and was hampered by reliability issues. The new, novel instrument presented in this work has employed new materials and construction techniques as a means of improving upon areas where the prior instrument fell short.

An initial task was to establish a suitable means of detecting thermal neutrons over large surface areas. In order to fulfil this requirement, a series of small scale, thin film surface barrier detectors were constructed and tested against a variety of characterised neutron sources. Dimensional information from the most favourable of the sample detectors was then used to inform a set of Monte Carlo based computer simulations. The purpose of these simulations was to deduce a set of potential geometries for a series of coherent moderators that could, once fabricated along with the recreation of surface barrier detectors upon their surfaces, offer the ability to resolve a spectrum of different neutron energies. Discussion is made with regards to the resultant data captured from each device in real world test environments and also looks at the merits of the prototype instrument created. A list of recommendations is made with respect to any future work in this area.