Investigation of neutron flux by thermoluminescence dosimeters in the neutron-gamma mixed field

Introduction: Neutrons have many applications in various fields, such as medicine. The important application of neutron in medical science is in Boron Neutron Capture Therapy (BNCT). Because of this, determination of neutron dose and flux is critical for the health maintaining of workers and patients exposed to this beam. The neutron radioisotope sources produce gamma rays in addition to the neutrons, and the neutron fields around these sources are mixed-field neutron-gamma fields. Since the separation of the dose of each radiation component in the compound field is difficult, the gamma-neutron mixed field dosimetry is a major challenge. International Commission on Radiation and Units (ICRU) recommends the use of a dosimeter pair for mixed-field dosimetry that have different responses to each component of radiation. One of the effective methods of neutron dosimetry is the use of the TLD-۶۰۰/۷۰۰ dosimeter pair. TLD-۶۰۰ is ۶Li enriched and TLD-۷۰۰ is ۷Li enriched. These dosimeters have the same sensitivity to gamma radiations but TLD-۶۰۰ is sensitive to thermal neutrons because of high capture cross-section of ۶Li, while in low fluxes, TLD-۷۰۰ has no sensitivity to thermal neutrons.   Materials and Methods: In this paper, in order to measure the neutron flux of the Ra-Be source in the core laboratory of the Faculty of Science of the University of Guilan. Six TLD-۶۰۰/۷۰۰ dosimeters were used in three intervals of ۷, ۱۴ and ۲۰ cm from the source   Results: After ۲۴ hours of irradiation, the intensity of the thermoluminescence of TLDs was measured by TLD reader. Finally, by calculating the calibration coefficient, the measured flux values by the TLDs were determined and compared with the calculated fluxes Conclusion: Results show that the measured and calculated values are in good agreement.

کلیدواژه ها:

neutron source ، Thermoluminescence Dosimeter ، neutron dosimetry ، neutron- gamma mixed field