Design of collimator of neutron diffractometer system at low power reactor TRIGA PUSPATI

Abstract

The objective of this research was to develop a neutron diffractometer system at a low power reactor TRIGA PUSPATI in Malaysia. Neutron diffractometer system consists of a number of vital instrumentations, namely collimator, monochromatic device and detector. However, this study only focus on the design and fabrication of the collimator. The value of neutron and gamma fluxes measured on beam-port 1 of reactor without collimator was 2.12x108 ncm-2s-1 and 1.97x107 ?cm-2s-1, respectively which are suitable for development of the system. Design of the collimators were done using the Monte Carlo N-Particle simulation software. The collimator is an aluminium tube containing suitable shielding components to filter and shape the neutron beam. Characterization of the shielding materials for the collimator were performed using thermo-luminescence detector devices and the Monte Carlo N-Particle software to investigate the materials with high attenuation coefficient on ionising radiations. The length of collimator was then optimized to obtain high value of thermal neutron flux for neutron diffractometer system. The beam was optimized by using the shortest length of collimator as it produced 6.24x106 ncm-2s-1 which is 20 % higher compare to the ideal flux required of 1.40x105 ncm-2s-1. The selected design of the collimator for neutron diffractometer system was installed inside beam-port 1 of reactor TRIGA PUSPATI. The research was useful to obtain measured fluxes from radial beam-port 1, to identify the ideal design of collimator, and to optimize neutron beams for development of neutron diffractometer system at reactor TRIGA PUSPATI in Malaysia.