New Experimental Data on the Sensitivity to Fast Neutrons of a Number of Sintered Commercial TL Phosphors

Abstract

Abstract The paper reports the results of an experimental investigation carried out during the last 3 years, on the neutron sensitivity of TL phosphors. 13 different types of solid TL detectors (chips, ribbons and discs) of commercial grade were included in the experiment. The irradiations were performed using narrow spectra of fast neutrons in the range 0.6-15 MeV, and wide spectra from a thick beryllium target (mean energy 7.5 MeV) and from a 252Cf source, with accurately known neutron and gamma components. The results in free air are in fairly good agreement with the data available in the literature. The sensitivity coefficient, kU, of 6LiF and of boron based dosemeters at the surface and inside a water phantom are much higher than in free air, as expected from thermalising properties of water. A further increase was obtained when the detectors were exposed in a tissue-equivalent container. The results indicate that the neutron-gamma discrimination by the classical twin-detectors technique could be based upon the use of 6LiF, lithium borate or, perhaps, magnesium tetraborate, as neutron-sensitive phosphors, and of 7LiF or calcium based TLDs as neutron insensitive dosemeters.