On the investigation of solution (etchant) parameters influencing the development of charged particle tracks by electrochemical etching (ECE)

Conductivity, viscosity and track-etch rate measurements were carried out for KOH solutions of various normalities and their mixtures with ethyl alcohol. The type of tracks studied were fast neutron induced recoil atom tracks and fission tracks in Lexan. It was observed that the presence of alcohol does not improve the EC track etch rates as significantly as it does for chemical track etch rates. This has been explained as follows: alcoholic solutions have lower conductivity. This suppresses to some extent the favourable effect of alcohol. EC track etch rates show a saturation at KOH concentrations of about 7 N, similar to chemical track etch rates which have a peak around 12 N. While the peak in chemical etching (CE) is due to viscosity alone, the same in ECE is due to both viscosity and conductivity. This shift of peak position in ECE towards lower concentrations is a result of lower conductivities at higher concentrations. It was also observed that very small volume of etchant is adequate for ECE of areas about 3 cm2 large. Because of this smaller requirement of etchant volume, it was possible to modify the ECE cell further to make it simpler. (author)