Characterisation of new LiF based TL materials for use in neutron spectrometry with Bonner spheres

The neutron spectrometry for radiation protection still constitutes a difficult task: the wide energy range and the presence of mixed n-gamma fields, makes the selection of the detectors a critical issue. Among the available experimental techniques, active and passive Bonner spheres spectrometers (BSS) have been used more than any other, due to the possibility to obtain spectral information from thermal to GeV neutrons. As thermal neutron sensor, ⁶LiF and ⁷LiF TLD pairs can be employed, due to a combination of several advantages: the suitability for use in pulsed fields, the low cost, the absence of electric supply and the n-gamma discrimination capability. In order to characterize the on-field performance of new commercially available TL materials, an experimental collaboration was established between INFN Frascati National Laboratories (LNF) and ENEA - Frascati, Italy. Six new type of ⁶LiF(Mg,Cu,P) TLDs (from TLD Poland), with different sensitive thickness, were paired with standard ⁷LiF(Mg,Cu,P) TLDs. The pairs were irradiated, in a standard BSS, to quasi-monochromatic neutron fields at the fast neutron generator of ENEA Frascati. The results of the test are presented and the suitability of the studied materials for radiation protection spectrometry is discussed