The role of preannealing etching in the revelation of fission fragment damage trails in Makrofol-E polycarbonate plastic detectors

Abstract

Abstract The process of chemical etching and thermal fading of the tracks is currently an object of extensive studies. In the present work, annealing out of the 252Cf fission fragment tracks in Makrofol-E detectors has been investigated in the temperature range 32–180°C. The tracks disappear (except some background) after annealing the detectors at 180°C for ten minutes, followed by etching in 6N KOH at 50°C for three hours. A preannealing etching step of 15 minutes duration makes the subsequent annealing ineffective and the tracks are revealed on further etching. Activation energy for the erasure of the latent damage trails is 0.84 ± 0.04 eV (19.4±1.0 k cal/mole). On annealing, average time required by the hole to jump and recombine with the molecular chain segment is 1.94x10-3 sec. It has been speculated that the hole undergoes 6 jumps prior to the nearest segment interaction with a diffusion coefficient of 1.32±0.1x10-13 cm2 /sec. The glass transition temperature (Tg = 411.5 °K) and the average molecular weight M relationship yields M = (3.7 ± 1.9)x103. Distance between the two nearest monomers (chain length) has been estimated to be 4.7A°.