Recording unit of squid-based magnetometer

The electronic recording unit of a squid-based magnetometer is described. The unit consists of an rf head, mounted tightly on a cyrogenic insert, and a control module. The input stage of a wide-band rf amplifier with a tunable resonant filter is built on a KF910 low-noise MOS transistor and has spectral densities of the noise voltage and current, adjusted to the input, of 1.7 nVHz/sup 1/2 and 0.95 pAHz/sup 1/2. The noise corresponds to a flux resolution of 5 x 10/sup -4/ Phi/sub 0/ Hz/sup -1/2 or a magnetic-moment resolution of 2.5 x 10/sup -13/ A x m/sup 2/Hz/sup 1/2/.