An optical method for fast neutron dosimetry using CR-39

Abstract

Measurements of the neutron doses in and around its sources are important for the purpose of personal and environmental neutron dosimetry. In the present work, we investigate a method for the measurement of neutron dose using the ultraviolet–visible (UV–VIS) spectra of an irradiated CR-39 plastic track detector. Therefore, a set of CR-39 plastic detectors was exposed to a source of fast neutrons, which has a yield of 0.68×108 s−1, and the neutron equivalent dose rate 1 m apart from the source is equal to 0.038 mSv/h. The samples were etched for 10 h in 6.25 N NaOH at 70±0.1 °C. Using the UV method, changes in the UV–VIS spectra of CR-39 with different neutron doses were obtained and the absorbance of the etched samples was measured using a UV–VIS spectrophotometer as a function of neutron dose. Further, it is observed that there is a linear relationship between the optical absorption of these detectors and neutron doses. Hence, the linear graph can be used as a calibration to measure the unknown dose of neutrons by knowing the optical absorption of the sample. These results are compared with previous work, and in principle, there is a good agreement with their investigations.