Ionizing radiation dosimetry in the absorbed dose range 0.01–50 MGy based on resistance and ESR linewidth measurements of organic conducting crystals

Abstract

The materials studied in the present work as high-dose dosimeters are members of a large class of molecular crystals which are organic conductors of electricity. Very different from each other in the details of their molecular and crystal structures, they all behave in the same way when subjected to increasing high doses of radiation, at least from the point of view of their electronic transport properties, because of the quasi-one-dimensional character of the conduction process. Their resistivities increase exponentially with the absorbed dose while their electron spin resonance (ESR) linewidths decrease exponentially. Very small single crystals less than 10 μm thick can be used as dosimeters in the dose range 0.01–50 MGy for γ rays as well as for electron irradiations, by applying four probe resistance measurements. Only a few compounds over a large number of candidates have been irradiated in the present work with γ-rays, low energy x-rays and electrons. In some favourable cases the energy and temperature dependences of the dosimeters have been checked experimentally. Their mass energy absorption coefficients and electron stopping powers have been also calculated. It is hoped to extend this kind of dosimetry to lower and higher doses by trying new compounds from the large family of organic conductors or by improving the resistivity and ESR measurement techniques.