EPR Imaging at a Few Megahertz Using SQUID Detectors

An apparatus being developed for electron paramagnetic resonance (EPR) imaging operates in the resonance- frequency range of about 1 to 2 MHz — well below the microwave frequencies used in conventional EPR. Until now, in order to obtain sufficient signal-to-noise radios (SNRs) in conventional EPR, it has been necessary to place both detectors and objects to be imaged inside resonant microwave cavities.