Effect of high-energy 7Li2+7Li2+ ions on the TL behavior of LiF:Mg,Cu,P detectors

Thermoluminescence (TL) of LiF:Mg,Cu,P (TLD-700H) phosphor irradiated with 24 MeV 7Li7Li ions at different fluences in the range 5×109–1×1012ions/cm2 (with corresponding doses in the range 620 Gy to 123.96 kGy) has been studied. The samples from the same batch were also exposed to γγ-rays from a Co60Co60 source for comparative studies. It has been found that at low fluences (5×109–1×1010ions/cm2) the TL glow curves of the samples irradiated with 7Li7Li ions have similar structures to that of γγ-irradiated sample, while at higher fluences (5×1010–1×1012ions/cm2) 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 5×1011ions/cm2, while that of the peak at 524 K increases till the maximum fluence 1×1012ions/cm2. 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 7Li7Li 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 10 K was observed, comparing with those induced by Co60Co60γγ-rays. The TL efficiency of LiF:Mg,Cu,P to 24 MeV 7Li7Li ion beam has been measured relative to γγ-rays of Co60Co60. Further, theoretical analysis of the glow curves of the ion beam and γγ-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.