Development of a compact electron spin resonance system for measuring ESR signals of irradiated fingernails.

The aims of this study were to develop and improve the sensitivity of an electron spin resonance (ESR) spectrometer and to demonstrate its functionality for dosimetry in measuring ESR signals from radiation-exposed fingernails. The newly-developed spectrometer was a lightweight (22 kg) one-box ESR device with a resonator showing a Q-factor higher than that of a previous Keycom model, which is quieter, without influence from magnetic modulation, and contains a fingernail positioner. The authors obtained the best measurement result after the cavity Q-factor was increased to more than 7,200 by continuous polishing of the inner surface of the cavity using deerskin.