Comparison among two fast neutron CR-39 ® materials: preliminary experimental studies

Abstract

The ENEA fast neutron dosemeter is based on a planar PADC (Poly Allyl Diglicol Carbonate) placed in a polyethylene holder. The present paper reports the results of a preliminary experimental comparison of a CR-39 ® material with the addition of 0.1% of DOP (Dioctylphthalate), produced by the Italian company Intercast Europe S.p.A., and TASTRAK material produced by the British company TASL (UK). The etching procedure is for both materials: pre-etching with 40% KOH water solution 6.25 N and 60% ethyl alcohol at 70 °C followed by 12 h of etching in 6.25 N KOH water solution. Dosemeters have been irradiated with neutron sources ( 241Am-Be) at the ENEA Calibration Service for Ionizing Radiations. For each kind of set of detectors, 10 have been irradiated free-in-air at 1 mSv of H*(10) with an 241Am–Be source at ENEA Calibration Service for Ionizing Radiations, whilst the other 40 detectors have been used as background samples. The dosimetric performance of the material for fast neutrons is expressed in terms of sensitivity, background value and lowest detectable dose. For each batch the value of the average background signal, the average neutron sensitivity and minimum detectable dose equivalent have been determined. Two identical tests have been completed and separated with a time of 6 months in order to evaluate the aging effect on the material stored in the same conditions. The results are compared with our acceptance test. A comparison of criteria the performance of the two CR-39 ® materials is reported.