Effect of ionizing radiation on noise in MgB2 thin film - a candidate material for detector development for post-Cassini planetary missions

A thin film of MgB2, grown on a SiN-Si substrate, with a superconducting transition temperature, Tc, near 39 K has been irradiated with γ-rays from a 60Co source. The total dose was 100 Krads (Si). Its pre- and post-irradiation noise has been measured and noise spectral density plots made. No change in dR/dT, pre- and post-irradiation was measured. At the mid-point of the transition, T = 38.24 K, a noise spectral density SV = 0.34 nV Hz−1/2 was measured at 10 Hz. The temperature noise, Kn, of the MgB2 film at different frequencies is compared to that of high temperature superconducting (HTS) thin films (YBaCuO and GdBaCuO with Tc ∼ 90 K) used currently in HTS transition-edge bolometers. Even with the observed post-irradiation small increase in noise, its lower Tc and Kn values predict that high performance far IR bolometers can be developed using MgB2 as a thermistor.