Estimation of the Optimum Etching Time and Etching Parameters for CR-39 Nuclear Tracks Detector by Applying Plasma and Chemical Etching Techniques

Abstract

Background: CR-39 nuclear track detectors are widely used in various fields, including science, technology, astronomy, and environmental preservation, to detect and register heavy ions, neutrons, and alpha particles. Objective: This study aims to determine the optimal etching duration for CR-39 nuclear track detectors by comparing etching methods: The wet etching (using a water bath) and the dry etching technique (using dielectric barrier discharge (DBD) plasma). Methods: The traditional etching method involved immersing CR-39 detectors in a sodium hydroxide (NaOH) solution at 70 °C for varying durations. The dry etching method employed employs a non-thermal DBD plasma system to etch solid-state nuclear track detectors (SSNTDs) without the use of chemical solutions. Results: Photomicrographs revealed that tracks from chemical etching became clearly visible after 1 hour and developed at 5 hours. In contrast, the dry etching technique was significantly faster; tracks began to appear after just 1 minute of DBD plasma etching and were fully developed at 5 minutes. The optimum track density for DBD plasma was 20340±56 tracks/mm² at 3 minutes, whereas the traditional water bath method achieved an optimum track density of 5238.0±5.7 tracks/mm² at 2 hours. The shorter etching duration in the dry method likely facilitates the emergence of latent tracks without overlap. Conclusions: The bulk etch rate (V_B) for CR-39 detectors using the dry DBD plasma etching technique was faster compared to the traditional chemical etching method. This demonstrates the efficacy of the dry etching process in significantly reducing etching time required for etching SSNDs.