Effect of high-energy Li-7(2+) ions on the TL behavior of LiF : Mg,Cu,P detectors

摘要

Thermoluminescence (TL) of LiF:Mg,Cu,P (TLD-700H) phosphor irradiated with 24 MeV Li-7 ions at different fluences in the range 5 x 10(9)-1 x 1012 ions/cm(2) (with corresponding doses in the range 620Gy to 123.96kGy) has been studied. The samples from the same batch were also exposed to gamma-rays from a Co-60 source for comparative studies. It has been found that at low fluences (5 x 10(9)-1 x 10(10) ions/cm(2)) the TL glow curves of the samples irradiated with Li-7 ions have similar structures to that of gamma-irradiated sample, while at higher fluences (5 x 10(10)-1 x 1012 ions/cm(2)) the relative intensities and fluence responses of the TL glow peaks were observed to vary with fluences increasing. The TL intensity of the dosimetric peak at 481 K saturates at the fluence 5 x 10(11) ions/cm(2), while that of the peak at 524 K increases till the maximum fluence 1 x 10(12) ions/cm(2), All the TL glow peaks show nearly sublinear behavior except the peak at 524 K, which exhibits supralinear. This has been attributed to the formation of more defects (trapping centers (TC)/luminescence centers (LC)) due to Li-7 ions implantation. during ion beam irradiation. The implantation has been confirmed from TRIM calculations. Moreover, on ion beam irradiation, a shift in the peak positions toward lower temperature side by around 10K was observed, comparing with those induced by Co-60 gamma-rays. The TL efficiency of LiF:Mg,Cu,P to 24 MeV 7Li ion beam has been measured relative to gamma-rays of Co-60. Further, theoretical analysis of the glow curves of the ion beam and gamma-irradiated samples was done by glow curve deconvolution (GCD) method to determine trapping parameters of various peaks. As LiF:Mg,Cu,P is highly sensitive and tissue equivalent TLD material and its peak at 524 K does not saturate even at high fluences. this peak may be used for the dosimetry of ion beams in medical and other applications. (c) 2007 Elsevier Ltd. All rights reserved.