Detection of alpha-particles utilizing polycarbonate foils processed by the electrochemical etching technique.

Abstract

Electrochemical etching of 250-micro m-thick polycarbonate foils was performed to determine if this system can be utilized to register alfa-particles. Experiments to examine the detection efficiency for alfa-particles, track diameter as a function of etching time, sensitivity as a function of waiting time, sensitivity as a function of etching time, and reproducibility were undertaken once the ability to detect alfa-particles was recognized. The efficiency of detection was somewhat low, namely I × 10−3% at the Bragg peak for monoenergetic alfa-particles without employing waiting time, up to 0.6% for particles from a thick source utilizing waiting time. Studies of track diameter as a function of etching time led to the discovery of two track size categories after alfa-particle irradiation and electrochemical etching. Sensitivity increased by 25 fold as etching time increased from 2 to 4 hr and by 100 fold for a waiting period of 15 days. Background was approx. 1 track/cm2. The results of these experiments and the inherent characteristics of the electrochemical etching system (thin, flat durable foils along with simple foil development procedures) indicate that the system could be utilized in personnel monitoring and internal dosimetry applications involving a-particle detection. Furthermore, this technique is cheaper and easier to use than photographic emulsions and fading is essentially non-existent with polycarbonate foils.