Effect of dopants on TL characteristics of LiF:Mg,Cu,P detectors
Abstract LiF:Mg,Cu,P detectors produced at the Institute of Nuclear Physics in Krakow have shown very good dosimetric characteristics. Understanding of the effect of the concentration and type of dopants is important in the characterization of TL materials. The aim of work was to investigate the influence of the type and concentration of the dopants on the photon energy response of these detectors by irradiations “in air” and on the ISO water phantom in the range of mean photon energies between 33 and 164 keV. The influence of dopants on the glow curves, sensitivity and reproducibility was also examined. Results showed that measured energy dependence values are lower compared to the theoretical values both “in air” and on phantom. The type and concentration of the dopants influence the shape of the glow curves and sensitivity while for energy dependence is more important the presence of certain activators, namely copper.
Thermoluminescence Properties of LiF(Mg,Cu,P) with Different Cu Concentrations
TL emission characteristics have been studied from LiF(Mg,Cu,P) samples prepared at the Institute of Nuclear Physics in Krakow, Poland in which the Cu concentration has been varied from 0.002 mol% to 0.5 mol% while the Mg content (0.2 mol%) and P content (1.25 mol%) were kept constant. Thermoluminescence has been recorded both as function of temperature and wavelength and absorption spectra were derived from diffuse reflectance measurements. The TL response of main dosimetry peak 4 increases with increasing Cu concentration up to 0.02 mol% and decreases for higher Cu content. With increasing Cu concentration the high temperature TL decreases. The emission spectra can be described with two overlapping emission bands peaking at 352 nm and 387 nm. The ratio of the intensities of both emission bands alters with temperature and Cu concentration. The high temperature thermoluminescence shows more 352 nm emission. No unique role of copper as trapping or as luminescent centre could be derived. Copper appears to play an indirect role in the trapping of charge carriers, possibly reducing the occurrence of higher order Mg defects and/or the improvement of the efficiency of the luminescent centre.
Anomalous Annealing Behavior of Arsenic Implanted Silicon as a Function of Dose and Energy
Anomalous annealing behavior of damage in As implanted Si has been investigated by channeling effect measurements. Room temperature As implants with doses from 1014 to 2 × 1016cm-2 at energies ranging from 50 to 250 keV into Si were annealed over the range of 600°C to 1100°C. Anneal temperatures ≥ 950°C reduce the disorder for ion doses of 0.5 to 1 × 1016 cm-2 at energies between 50 and 250 keV. Anomalously high residual disorder was found for the intermediate doses of 2 × 1014 to 2 × 10/cm2 implanted above 100 keV. For this intermediate dose, annealing of implants performed at liquid nitrogen temperatures did not show significant reduction in this damage. However implants at 200° to 300°C indicate a lower amount of damage compared to the room temperature implants.