Influence of concentration of magnesium on the dose response and LET-dependence of TL efficiency in LiF:Mg,Cu,P (MCP-N) detectors
1998; Elsevier BV; Volume: 29; Issue: 3-4 Linguagem: Inglês
10.1016/s1350-4487(98)00026-2
ISSN1879-0925
AutoresP. Bilski, M. Budzanowski, P. Olko, M.P.R. Waligórski,
Tópico(s)Nuclear Physics and Applications
ResumoThe highly-sensitive LiF:Mg,Cu,P phosphor, unlike the supralinear LiF:Mg,Ti, exhibits a linear–sublinear dose response after high doses of photon radiation. Also, LiF:Mg,Cu,P shows a much stronger decrease of relative efficiency with increasing ionisation density, especially for heavy charged-particle irradiation. The magnesium dopant most likely governs the trap structure in both phosphors. Dose-response and LET-dependence were therefore studied in LiF:Mg,Cu,P with different concentrations of Mg. Samples of LiF:Mg,Cu,P detectors with eight different values of magnesium concentration CMg ranging from 0.05 to 0.8 mol%, were produced in which the concentration of P and Cu was fixed at 1.25 and 0.05 mol%, respectively. Detectors were irradiated with 5.3 MeV alpha-particles and 137Cs gamma-rays and relative efficiency evaluated for all groups of samples. Relative efficiency ηαγ appears to decrease with increasing magnesium content: from ηαγ≈0.13 at CMg=0.05 mol% to ηαγ≈0.06 at CMg=0.20 mol%, and is less dependent on CMg at higher concentration of Mg. In the study of LiF:Mg,Cu,P response after 137Cs photon doses (1–1000 Gy) in samples with CMg=0.1 and 0.2 mol%, typical sublinear response was observed, the sublinearity of 0.1 mol% detectors commencing at higher doses. In contrast, in the least Mg-doped sample (0.05 mol%) strong supralinearity in the dose response was found, resulting from the growth of a new peak at about 200°C which at 1000 Gy and at 500 Gy dominates the TL glow-curve over the usual main peak at 240°C.
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