ELECTROCHEMICAL ETCHING OF CR-39 PLASTIC - APPLICATIONS TO RADIATION-DOSIMETRY

The homopolymer CR-39 has lately been shown to be the most sensitive detector of ionizing particles of any of the plastic track detectors yet investigated. The paper reports the development of track images in CR-39 by the electrochemical etching (ECE) technique. Optimum conditions of the applied electrical field and frequency as well as of etching and pre-etching are reported for the plastic. Changes in the diameters of etch-spots made by normally-incident fission fragments and α-particles are studied as a function of their fluence. In addition to fission-fragments, ECE spots have been obtained for high-energy (7-9 MeV) α-particles such as may be registered during radon dosimetry. A relatively high efficiency for the detection of fast neutrons is achieved, partly owing to the etchability of proton recoil tracks; this efficiency is a function of neutron fluence. By using a suitable pre-etching stage it is possible to use the ECE technique to discriminate between tracks due to different types of particle such as α's and fission fragments; or between short-range, high Vt (along-the-track etching velocity) as against long-range, low Vt particles. © 1980.