Dosimetry of d(14)+Be neutrons with the two-peak method of LiF TLD-700

The fact that for in-phantom irradiations the 2000C peak of TLD-700 (0.007% 6LiF, 99.993% 7LiF) has a much lower sensitivity to neutrons than to gamma rays and the higher temperature peak has comparable sensitivities to both radiations is of relevance the use of the two-peak method for the dosimetry of therapeutically used fast-neutron beams. The difference in the neutron sensitivities of the two peaks of TLD-700 is greater than that of the peaks of any other TLD including CaF:Tm. Since the gamma ray absorbed dose content in cyclotron-produced neutron beams is small, the supralinearity of the high-temperature glow peak does not pose a serious problem. Also by using thin ribbons, slow heating rates (about 3.50C s-1) during the TL readout and by applying predetermined individual calibration factors for each peak of each detector, the intensities of the glow peaks could be measured with a reasonable precision. To make the two-peak method of TLD-700 more versatile, efforts should be made to standardise a technique of sensitisation which could enhance the intensity and enlarge the absorbed dose range of linearity of the higher temperature glow peak. (author)