Application of high performance DC SQUIDs in precision measurement technique

In this review the performance of a DC SQUID system with Nb-NbO/sub x/-Pb/In/Au window-type Josephson junctions is described. The SQUIDs and the SQUID control units were developed for universal applications in precision measurement technique. Under optimum conditions a flux noise level of 2/spl times/10/sup -6/ /spl Phi//sub 0///spl radic/Hz was achieved corresponding to an energy resolution of 3/spl times/10/sup -31/ J/Hz. The contribution gives the design of the DC SQUID device and summarizes recent results of its application in precision measurement technique. The applications include a cryogenic current comparator for non-destructive measurement of the beam intensity produced in a particle accelerator, a high-sensitive SQUID voltmeter for investigations of the low-field Hall coefficient of high purity metals, the upgrade of a multichannel RF SQUID neuromagnetometer for biomagnetic research, and a planned high-precision experiment in fundamental physics.<>