Isothermal Decay of Glow Peaks in LiF:Mg,Cu,P

Abstract

Isothermal decay (ID) experimental data for peaks 2, 3 and 4 of LiF:Mg,Cu,P (China) are presented. For every peak the ID has been measured at different temperatures, so that the evolution of life-time with temperature has also been determined. Peaks 2 and 4 present a very simple exponential decay typical of first order kinetic processes. Peak 3 decay is more complex due to the unavoidable contribution of the intense peak 4. After the subtraction of this contribution, peak 3 decay is exponential indicating first order kinetics for this peak too. From the good linear dependence of lnt on l/T, values for the activation energy and the frequency factor for all the peaks studied have been obtained. Peak 4 parameters have shown to be very critically dependent on the cooling rate in the annealing procedure. The LiF:Mg,Cu,P decay features are discussed with regard to those of LiF:Ti,Mg (TLD-100).

Low-temperature (80 - C) annealing characteristics of LiF:Mg, Cu, P

“…We cannot offer a conclusive explanation for the disagreement between the E and s values of Yossian et al (1993) and Mahajna et al (1993) and those of the present work (as well as those of Delgado et al (1990Delgado et al ( , 1993), although our experimental procedure follows the line of Yossian et al (1993). However, we can note the particular experimental conditions and analysis of the present work, and the differences from those of Yossian et al (1993).…”

“…For glow-peak 5 of LiF:Mg, Ti, activation energies of the order of 2.2 eV and frequency factors of the order of 10 21 s −1 have been found. In the case of the main glowpeak 4 of LiF:Mg, Cu, P even higher values of trapping parameters have been observed by Srivastava and Supe (1988) and Delgado et al (1993) and in the present work. These values were considered extremely high and outside acceptable physical limits, according to which the frequency factor cannot exceed the Debye lattice vibration frequency (10 12 -10 14 s −1 ).…”

“…Srivastava and Supe (1988) found an activation energy of 2.38 eV by applying the fractional glow technique. Delgado et al (1990Delgado et al ( , 1993, by applying the isothermal decay method, found an activation energy up to 2.1 eV and frequency factors of the order of 10 21 s −1 . On the other hand, Mahajna et al (1993), by applying the 'prompt' and the 'residual' isothermal decay methods, obtained much lower trapping parameters (1.34 and 1.48 eV for prompt and residual decay respectively).…”