Sensitization effects on the tracks of neutron irradiated CR-39 detectors treated with CO2 under pressures greater than 0.6 MPa

ESR dosimetric properties of gamma irradiated different origin eyeglass samples

In the present research, mineral and organic origin eyeglasses (CR-39) were examined with respect to their potential application in the dosimetry of ionizing radiation by using electron spin resonance (ESR) technique. Before irradiation, organic and mineral origin eyeglasses did not exhibit any ESR signal. But they do produce radiation-induced ESR spectra after gamma irradiation. The variations of the radiation-induced resonance signals of organic and mineral origin eyeglasses with microwave power and modulation amplitude were investigated and the optimum spectrometer operating conditions were determined. The dose-response curves of the organic and mineral origin eyeglasses exposed to gamma radiations were found to be described well by a linear and single exponential saturation functions in the dose ranges of 0.1-10 and 0.05-10 kGy, respectively. For mineral eyeglasses this behavior was linear at lower doses (0.05-1 kGy). Despite the observed fading with time in the signal intensity, measurable ESR signals were obtained even 54 days after irradiation for organic origin eyeglass, while the corresponding value for the mineral eyeglass was 154 days. The study also showed that the thermal stability of the radiation-induced ESR signal of mineral eyeglass sample was higher than the signal of organic origin eyeglass.

Effects of Storage Time and Pre-Etching Treatment of CR-39 Detectors on Their Response to Alpha Radiation Exposure

Radon passive monitors based on solid state nuclear track detectors (SSNTD), especially CR-39, are widely used in radon and thoron studies. They may be subjected to the influence of external factors, like changing of temperature, humidity, and pressure, both before and during the measurement. Evaluation of the exposed detectors involves chemical processing, whose conditions also influence the measurement results. The aim of this study was to check several factors, as to whether they may modify the response of CR-39 detector: concerning the phase before evaluation, storage time, and temperature during storage; and concerning the evaluation procedure, etching time, and pre-etching treatment using hot water and carbon dioxide atmosphere. Two experiments were conducted by irradiation of CR-39 detectors using alpha particles emitted from a mono-energetic ²⁴¹Am source and exposed in radon atmosphere. Track density dependence of the age of production was found to be statistically not significant. On the other hand, pre-etching treatment using hot water and carbon dioxide with different etching times showed statistically significant effects on track area, track sensitivity, and roundness. It was concluded that there are simple methods to increase performance of nuclear track detectors, and that storage time is not a factor of concern.