Some aspects and results of the electrochemical etching of a thin-foil track detector

Abstract

Some recent papers describe the ‘resonance’ effect for the field strength and frequency in the electrochemical etching (ECE) of solid state nuclear track detectors. In this paper we report the effects for the commercially available cellulose nitrate foil, namely Kodak LR-115 type 2. This foil was irradiated with alpha particles (from a 239Pu source) and then treated electrochemically. We find that the maximums of the frequency resonance curves are located between 0.5 – 1.5 kHz and depend on the electric field strength, applied on the Kodak foil; whereas the field-strength — curves have their maximums between 0.5 – 1.2 kV and also depend on the frequency. The ‘appearance’ (or emergence) effect of the latent tracks was used as a criterion of track-enhancement in the electrochemical etching. The results obtained, especially the shapes of frequency resonance curves, are in very good agreement with those curves that can be predicted from a theoretical consideration of the mechanisms of the electrochemical etching phenomenon. In the theory presented below we consider the foil as a dielectric between two plates of a capacitor. It vibrates mechanically in the alternating electric field. This vibration increase the probability of the interaction between ions and the material to be etched. Also, the effect of an additional lux of the ions of electrolite, due to the action of the alternating field in the etchant, is considered. Both the assumptions permit one to predict the shape of resonance curves and to find some of the characteristic parameters of track detector material.