DEVELOPMENT OF PASSIVE DETECTOR BASED SINGLE MODERATOR NEUTRON SPECTROMETER

• Main Author: Rasito
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/82951
• Institution: Institut Teknologi Bandung

A single-cylindrical neutron spectrometer (SCNS) has been developed with three passive neutron detectors, namely Au, In, and LiF. Au activation foils are used for high neutron flux fields, In foils for medium flux measurements, and LiF TLDs for low neutron flux measurements. The response of each detector as a function of neutron energy was determined by simulation using the Monte Carlo MCNPX 2.7 program in the energy range 10-9 – 100 MeV with 24 energy groups. Validation of the spectrometer was carried out by measuring the AmBe neutron spectrum and comparing it with the AmBe reference neutron spectrum in ISO-8529. The validation results obtained for SCNS-Au were 3%, SCNS-In 10%, and SCNS-LiF 7%. Neutron spectrum measurement tests were carried out for six types of neutron sources, namely AmBe in containers, nuclear reactor cores, neutron radiography, medical linacs, cyclotrons and cosmic rays. The neutron spectrum from measurements at each neutron source was also compared with the neutron spectrum from the simulation results. The results of measuring the AmBe neutron spectrum in the container and comparing the PHITS simulation show the same neutron spectrum with a difference in total neutron flux value of 2% for SCNS-Au and 1% for SCNS-In. The results of measuring the neutron spectrum in the Triga Mark II reactor core showed a difference with the simulation results of 2.2%. The results of neutron spectrum measurements at the RSG-GAS neutron radiography facility using SCNS-Au showed a difference with simulation of 30%. The results of neutron spectrum measurements in the 11 MeV cyclotron showed a difference with the simulation of 8% for SCNS-Au and 7% for SCNS-In. The results of cosmic neutron spectrum measurements using SCNS-LiF obtained results that were 27% smaller than the EXPACS estimate. Based on validation and measurement tests, it shows that the results of the development of a single cylinder moderated neutron spectrometer with a passive detector have the ability to measure the neutron spectrum for various sources with quite good results.