Response of various types of lithium fluoride MCP detectors to high and ultra-high thermal neutron doses

Abstract

Abstract Based on the newly discovered feature of LiF:Mg,Cu,P (MCP) detectors’ glow-curves at high and ultra-high doses, a new method of thermoluminescent (TL) measurement of radiation doses ranging from micrograys up to a megagray, has been recently developed at the Institute of Nuclear Physics (IFJ). The occurrence of a new, well separated TL peak has been observed in their glow-curves resulting from many specific radiation qualities, among them gamma, electron and proton beams, for doses of about 50 kGy and higher. The occurrence of the peak B follows significant growth of previously observed high temperature peaks of the glow-curve following smaller doses. This allows MCPs to be used for dosimetry of specific radiation types in the ultra-high dose range. In order to verify the response of MCP detectors to very high doses of high-LET radiation, the glow-curve behaviour of different types of these detectors, resulting from high and ultra-high thermal neutron fluences, was studied in this work. TLDs were exposed to the neutron spectrum of the TRIGA Mark II reactor at the Reactor Research Centre at the Jožef Stefan Institute in Ljubljana. The occurrence of the high dose peak B in the MCP detectors’ glow-curve resulting from high-LET neutrons was confirmed. Results of this experiment are presented in this paper. Thus the method of ultra-high dose TL measurements was proved to be useful in interpreting the glow-curves following thermal and epithermal neutron irradiation.