Three different methods have been used to determine the trap depth E and frequency factor S associated with glow peaks 2 to 5 in single crystals of LiF (TLD-100). The methods used were (i) the total glow peak method, (ii) the variable heating rate method and (iii) the isothermal decay method. Good agreement is found for the values of the trap parameters determined by the three methods. The peaks obey simple first-order kinetics for the thermal untrapping of electrons, following the model of Randall and Wilkins (1945). The average E values determined for peaks 2 to 5 are 1.10, 1.22, 1.60 and 2.06 eV with S values of 2*1013, 4*1013, 3*1016 and 5*1020 s-1 respectively. The results are compared with the widely differing values reported by other authors.

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Comments on the result given by Kathuria and Sunta (ibid., vol.12, p.1573, 1979) for the order of kinetics of peak V of the TLD-100 thermoluminescence. Further results are presented to support the view that peak V has constant first-order kinetics.

Improvements have been made to the Monte Carlo modelling used to calculate the response of the neutron survey instruments most commonly used in the UK, for neutron energies up to 20 MeV. The improved modelling of the devices includes the electronics and battery pack, allowing better calculations of both the energy and angle dependence of response. These data are used to calculate the response of the instruments in rotationally and fully isotropic, as well as unidirectional fields. Experimental measurements with radionuclide sources and monoenergetic neutron fields have been, and continue to be made, to test the calculated response characteristics. The enhancements to the calculations have involved simulation of the sensitivity of the response to variations in instrument manufacture, and will include the influence of the user and floor during measurements. The practical implications of the energy and angle dependence of response, variations in manufacture, and the influence of the user are assessed by folding the response characteristics with workplace energy and direction distributions.

The heating rate is an important, though often neglected experimental variable in TL measurements. Lithium fluoride (TLD-100) samples have been heated at rates up to 100 degrees C s-1 during TL readout. The change in TL glow peak intensities and (Mg2+-V-) dipole concentration during readout have been investigated for varying heating rates and initial (Mg2+-V-) dipole concentrations. To avoid significant dipole clustering during TL readout, samples must be heated at rates greater than 10 degrees C s-1. However, TL glow peak intensities alter dramatically with increasing heating rates even up to 100 degrees C s-1 where dipole clustering is negligible. It is concluded that because of defect clustering during readout, TL measurements are unlikely to reflect the defect state that existed in the sample just prior to measurement. In particular it is proposed that, for rapidly quenched samples, glow peak 5 would not exist if the sample would be heated sufficiently rapidly.