Alpha track registration and revelation in CR-39 using new etching method for ultratrace alpha radioactivity quantification in solution media

摘要

A CR-39 based method was developed for measuring the ultra-trace alpha radio activities in aqueous samples having curie levels of gamma/beta-radio activities. The chemical etching method was optimized to reveal the alpha tracks in CR-39. This newchemical etching method involved the use of a phase transfer catalyst tetraethylammonium bromide which reduced the track revelation induction time without deteriorating the track-etch parameters. The alpha track-etch parameters such as bulk-etch rate, track-etch rate, induction time, and the critical angle of alpha track registration were measured at 60 and 70 degrees C, with and without using a phase transfer catalyst in the chemical etching for the comparison and optimization. The track registration efficiency of CR-39 in the solution medium was measured using the samples having known alpha activity of Pu-mix, and value obtained was found to be (4.42 +/- 0.12) x 10(-4) cm. The registration efficiency value thus obtained was corroborated with the expected efficiency expected from the calculated range of alpha particles in the solution. This CR-39 based method was employed to quantify the alpha activity, as low as 0.2 BqmL(-1), in the aqueous radiopharmaceutical samples having the curie levels of gamma/beta-radio activities.