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 oil a SiN-Si substrate, with a superconducting transition temperature, T-c, near 39 K has been irradiated with gamma-rays from a Co-60 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/d T, pre- and post-irradiation was measured. At the mid-point of the transition, T = 38.24 K, a noise spectral density S-V = 0.34 nV Hz(-1/2) was measured at 10 Hz. The temperature noise, K-n, of the MgB2 film at different frequencies is compared to that of high temperature superconducting (HTS) thin films (YBaCuO and GdBaCuO with T-c similar to 90 K) used currently in HTS transit ion-edge bolometers. Even with the observed post-irradiation small increase in noise, its lower T-c and K-n values predict that high performance far IR bolometers call be developed using MgB2 as a thermistor. (c) 2006 Elsevier B.V. All rights reserved.