Further studies on the non-universality of the TL-LET response in thermoluminescent LiF and Li₂B₄O₇: The effect of high temperature TL

Three batches of thermoluminescent bulb dosimeters of LiF (TLD-100, 600, 700 - Harshaw) and two batches of Li₂B₄O₇ (TLD-800 - Harshaw) were irradiated with ⁶⁰Co γ rays, 13.54 meV monoenergetic neutrons and 3.8 MeV alphas. The relative population of high temperature TL peaks (peaks 6 and 7 in LiF) was found to be both batch and ionization density dependent with ε{lunate}_T>¹ⁿ=0.206±0.02, ε{lunate}_T>2n=0.288±0.02, ε{lunate}_T>^1α=0.205±0.02, ε{lunate}_{T >}^2α=0.316±0.02, ε{lunate}_T>^3α=0.355±0.02, and ε{lunate}_T>1γ=0.035±0.01ε{lunate}_T>^2γ=0.102±0.015, ε{lunate}_T>^3γ=0.123±0.015. In li₂B₄O₇, no variationa was observed in the glow structure as a function of batch or type of radiation. It follows immediately, therefore, that the batch variations previously reported by Horowitz et al. in the relative total TL production efficiency, η, remain unchanged at η₁ = 0.775 ± 0.007 and η₂ = 1.105 ± 0.017 in Li₂B ₄O₇. We calculate batch values of the relative partial TL production efficiency for LiF, η₄₊₅, to be 0.288 ± 0.008 and 0.333 ± 0.008 for batches 1 and 2 respectively following neutron irradiation and 0.14 ± 0.02, 0.16 ± 0.01 and 0.213 ± 0.015 for batches 1, 2, 3 respectively following alpha irradiation. The batch variations in η₄₊₅ (i.e. the major dosimetric peaks in LiF) remain, therefore, 14.5% and 41.4% following neutron and alpha irradiation respectively. The batch variations in η and ε{lunate}_T> are apparently associated with large variations in the concentrations of Ba, Al and Cr in LiF and Al, Si in Li₂B₄O₇. The previous conclusions arrived at by Horowitz et al., regarding the non-universality of the TL-LET dependence in LiF and Li₂B₄O₇ cannot be explained by batch variations of high temperature TL and remain, therefore, unmodified.