Determining Albedo Neutron Dose Using LiF: MCP and a Dose Calculation Algorithm

Abstract

Thermoluminescent dosimetry (TLD) techniques employing lithium fluoride doped with magnesium and titanium (LiF:Mg,Ti) (commonly known as TLD 100) has been widely used in many laboratories for occupational dose monitoring, including the dosimetry laboratories in Botswana. Typically, TLD 100 is not used for measuring doses from neutron exposure. It has been shown, however, that LiF doped with magnesium, copper, and phosphorus (LiF:MCP) can measure doses from albedo neutrons. The objective of this work was to demonstrate that both 6Li and 7Li can be used to measure neutron doses with LiF:MCP. A TLD system comprised of a Harshaw TLD reader 8800 Plus with an onboard 90Sr irradiator, Harshaw TLD cards, and a holder was used to carry out the demonstration. The TLD system was calibrated in parts. The TLD cards were calibrated to ensure the sensitivity of the cards was uniform. The reader was calibrated to ensure quantify its sensitivity. The system was calibrated using National Institute of Standards and Technology (NIST) traceable 137Cs for photons. An algorithm was used to be able to measure doses from a 241Am:Be neutron field. Results showed that using LiF:MCP together with a dose calculation algorithm, measurement of albedo neutron doses is possible.