Radiation safety in accelerators: neutron dosimetry and spectrometry using prompt gamma measurements

In an accelerator radiation environment neutron dosimetry and spectrometry face several challenges while carrying out radiological safety analysis. One of the major challenges, specifically in high energy particle accelerators, is the large dynamic range of neutrons that are emitted because of the interactions of energetic projectiles with different target materials. The neutron energies span a wide range from about thermal to about 1 GeV or more. There are many techniques that are adapted to solve this problem leaving scope for further improvement in this area. The present paper describes a newly developed technique based on prompt gamma photo-peak area measurement using a gamma-ray spectrometer. The present work demonstrates utilization of the energy dependent five prompt gamma responses of the Pb-covered BHDPE-HDPE system and the corresponding prompt gamma intensities (areas under the photo peaks) to estimate the incident neutron energy distribution as an under-determined de-convolution problem. Such an under-determined set of equations are solved using the genetic algorithm based Monte Carlo de-convolution code GAMCD