Study of the response of phenol compounds exposed to thermal neutrons beams for Electron Paramagnetic Resonance dosimetry

This paper reports the results regarding a new organic compound (IRGANOX® 1076 phenols) with and without low content (5% by weight) of gadolinium oxide (Gd2O3) for Electron Paramagnetic Resonance (EPR) dosimetry of neutron beams. The dependence of EPR signal as function of neutron dose was investigated in the fluence range studied between 1011 cm-2 to 1014 cm-2. We evaluated also the effect of gadolinium on 60Co gamma photon sensitivity of this organic compound. Our analysis showed that a low concentration of gadolinium oxide (of the order of 5% of the total mass of the dosimeter) can enhance the thermal neutron sensitivity more than 10 times with a small reduction of photon tissue equivalence. The free radicals produced after irradiation of photons and neutrons are stable for more than first 300 h after irradiation. The presence of additives does not substantially modify the fading of the EPR signal induced by photons and neutrons in the first 15 days after exposure.