Dosimetry of a radioisotope source of neutron by thermoluminescence dosimeters (TLD-600/700)

Neutrons have many applications in various fields, such as industry and medicine. In nuclear facilities, and especially in electricity production, we are faced with such radiation. Because of this, determination of neutron dose is critical for the health of workers and patients exposed to this beam. The neutron radioisotope sources produce gamma rays in addition to the neutron, and the neutron fields around these sources are mixed-field neutron-gamma fields. Different methods of dosimetry of the neutron field include the method of gold foil activation and the method of using a thermoluminescence dosimeter pair. One of the effective ways of neutron dosimetry is the use of the TLD-600/700 thermoluminescence dosimeter pair. The TLD-600 is sensitive to thermal neutrons due to the richness of 6Li (which has a high thermal neutron absorption cross section) but the TLD-700 does not have thermal neutron sensitivity in low fluxes. In this paper, to measure the neutron dose from the Ra-Be neutron source in the core laboratory of the Faculty of Science of the University of Guilan, six TLD-600/700 dosimeters were used in three intervals of 7, 14 and 20 cm from the source. Finally, by calculating the neutron dose through the source flux and estimating the calibration coefficient, the dose rate measured by the TLDs was determined and compared with the calculated dose rate.