AN IMPROVED CR-39 DETECTOR MATERIAL WITH LOW BACKGROUND FOR ALPHA AND NEUTRON MEASUREMENTS

In collaboration between the competent authority and the industry, detector material based on polydiethylene-glycol-bis (allyl carbonate) with the trade name PATRAS has been developed. The detector material is produced under strictly controlled conditions, e.g. a special bi-distillation of the monomer and a noble gas bubbling of the casting solution until saturation and, to ensure a very low background track density, subjected to an additional pretreatment of unirradiated detector plates. The resulting detector material is characterised by a very low background track density and a high sensitivity. Optimal chemical and electrochemical etching parameters for alpha particles and neutrons are represented in detail. The variation of background track density and the alpha sensitivity under defined irradiation conditions of a total of ten production batches of PATRAS detector material are reported and show a good reproducibility. Pre-irradiation annealing of the detector material and stirring of the etching solution during chemical etching increases the alpha sensitivity of the detector material. Results of investigating dosimetric properties, e.g. the alpha sensitivity at various energies, are reported.