%V 322 %K DEER, EPR, HYSCORE, Preamplifier, Probehead, SNR enhancement %T A sensitivity leap for X-band EPR using a probehead with a cryogenic preamplifier %C United States %D 2021 %X Inspired by the considerable success of cryogenically cooled NMR cryoprobes, we present an upgraded X-band EPR probehead, equipped with a cryogenic low-noise preamplifier. Our setup suppresses source noise, can handle the high microwave powers typical in X-band pulsed EPR, and is compatible with the convenient resonator coupling and sample access found on commercially available spectrometers. Our approach allows standard pulsed and continuous-wave EPR experiments to be performed at X-band frequency with significantly increased sensitivity compared to the unmodified setup. The probehead demonstrates a voltage signal-to-noise ratio (SNR) enhancement by a factor close to 8× at a temperature of 6 K, and remains close to 2× at room temperature. By further suppressing room-temperature noise at the expense of reduced microwave power (and thus minimum -pulse length), the factor of SNR improvement approaches 15 at 6 K, corresponding to an impressive 200-fold reduction in EPR measurement time. We reveal the full potential of this probehead by demonstrating such SNR improvements using a suite of typical hyperfine and dipolar spectroscopy experiments on exemplary samples. %L discovery10117477 %O This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. %A M Šimėnas %A J O'Sullivan %A CW Zollitsch %A O Kennedy %A M Seif-Eddine %A I Ritsch %A M Hülsmann %A M Qi %A A Godt %A MM Roessler %A G Jeschke %A JJL Morton %J Journal of Magnetic Resonance