A new EPR dosimeter based on 2:1 mixture of Li2C2O4:Na2C2O4 for gamma and neutron dosimetry

Electron paramagnetic resonance (EPR) investigations of Li2C2O4, Na2C2O4 mixed in proportion 1:0, 0:1, 1:1, 2:1 and 3:1 were carried out to measure the absorbed dose from photons and thermal neutrons in a mixed radiation field. A single line spectrum of CO2− radical anion centered around g=2.0045±0.0005 was obtained in the respective cases on gamma and neutron irradiation. Except Na2C2O4, other mixtures had shown increase in line width on neutron irradiation possibly due to relaxation effects. Of all combinations, the 2:1 mixture is the more sensitive material for gamma and thermal neutrons. Intensity of CO2− radical signal in 2:1 Li2C2O4:Na2C2O4 mixture was found to be linear from 0.006 to 11 kGy for gamma and 40-1530 kGy for thermal neutron doses. Radical signal was found to be stable over a period of 300 days with marginal fading of less than 1 percent. Experimental results thus obtained suggest 2:1 Li2C2O4:Na2C2O4 mixture as the potential neutron dosimeter for medium and high dose range.