Abstract
The alpha particle track diameter dependence of the free volume holes size (V-f) in DAM-ADC and CR-39 nuclear track detectors was investigated using positron annihilation lifetime technique. The effect of temperature on the alpha particle track diameter and free volume were also investigated in the T-range (RT-130 degrees C). The obtained results revealed that the values of ortho-positronium lifetime tau(3) and V-f increases while I-3 slightly increases as T increases for the two detectors. The values of tau(3), V-f and I-3 are higher in CR-39 than DAM-ADC. The interpretation of obtained results is based on the fact that increasing T leads to significant enhancement of thermal expansion of the polymer matrix and consequently V-f increases. The track diameter increases as T increases. This can be explained by the fact that the increase in T increases the crystal size and V-f in the polymer. A relationship between V-f and the alpha particle track diameter was obtained. Moreover results of detector irradiation, along with free volume evaluation are addressed and thoroughly discussed. (C) 2015 Elsevier B.V. All rights reserved.