Electron Spin Resonance Spectra of Irradiated Textiles: Applications to the Dosimetry of Ionising Radiations

In order to be able to evaluate the dose received by a person accidentally exposed to gamma radiation, a method based on observing changes induced in the intensity of the electon spin resonance (ESR) spectrum of irradiated fabrics has been developed. About ten different fabrics were studied: the fibers of three of these fabrics exhibited useful dosimetric properties (cotton, polypropylene, quartz based fibers). In order to minimize the effects of fiber anisotropy on the ESR spectra, a system was devised to rotate samples in the measurement cavity during the time in which the spectrum is recorded. The relation between the intensity of the ESR signal and the ionizing radiation dose is linear over a large dose range (up to a few kilograys). However, the existence of an intrinsic signal from the non irradiated fabric makes it difficult to determine low doses. The minimum dose threshold was raised by employing a special sample preparation technique. The effects of temperature on the ESR signal (thermal fading) from irradiated fabrics was also studied. These results should be considered in the general context of the dosimetry of ionizing radiations through the effects of such irradiations on organic materials. The main results obtained in this field and their usefulness are discussed.