Experimental Correction for Thermal Neutron Sensitivity of Gamma-Ray TL Dosemeters Irradiated at BNCT Beams

Abstract

For gamma ray dosimetry of boron neutron capture therapy, an experimental method for correction of the thermal neutron sensitivity of TL dosemeters is required. For this purpose, a method using a thermal neutron filter was used in this study. TL detectors MCP-7s (7LiF:Mg,Cu,P) from TLD Niewiadomski & Co. (Krakow, Poland) and TLD-700 (7LiF:Mg,Ti) from Harshaw Chemical Co. were irradiated in a thermal neutron beam, bare as well as shielded from thermal neutrons using a 6Li filter container. MCP-7s detectors were found to be three times less sensitive to thermal neutrons than were TLD-700 detectors. Since the abundance of 6Li in 7LiF, causing the thermal neutron sensitivity, varies between different manufacturer batches of TL detectors, it is concluded that when determining the correction factors for the thermal neutron sensitivity, it is most convenient to use a figure of merit, the value of which may be derived using the method introduced in this study.