NEW TL DETECTORS FOR PERSONAL NEUTRON DOSIMETRY

One of the main objectives in the application of TL detectors to neutr on dosimetry is to obtain a high ratio of neutron to gamma response fo r a better separation of the neutron component. In the case of (LiF)-L i-6, one may reduce the effective thickness of the detector in order t o exploit the difference between neutron and gamma absorption, either by making the sensitive layer of TL chip thinner or by reducing its tr ansparency to TL light. Two new types of sintered (LiF)-Li-6:Mg,Ti det ectors have been developed: a sandwich detector with a non-thermolumin escent LiF base, and a detector in which the phosphor is mixed with gr aphite. Three thicknesses of the sensitive layer (45, 60, 80 Mg.cm2) a nd two carbon concentrations (1%, 4%) were tested. The detectors were irradiated by moderated neutrons from Pu-Be and Cf-252 sources and by thermal neutrons from a nuclear research reactor. Results of measureme nts indicate that for the detector of thickness 45 mg.cm-2 the ratio o f neutron to gamma response increases 2-4 times, compared with the Har shaw TLD-600 while the neutron sensitivity is maintained. Other dosime tric characteristics of the detector remain unchanged, making it possi ble to use standard annealing and readout procedures. The new detector s will be applied in a personal neutron albedo dosemeter with a detect ion limit better than 100 muSv in a gamma background of the range of s everal mSv.