LOW-NOISE LTS SQUIDS FOR APPLICATION IN GRAVITATIONAL EXPERIMENTS

The Weak Principle of Equivalence (WEP) is proved up to now with an ac curacy of 1 x 10(-12). Short range free fall experiments attained an a ccuracy of 5 x 10(-10) only, Microgravity facilities such as the ''Dro p Tower Bremen'' enables long range free fall experiments which may im prove the accuracy of free fall tests to < 10(-12) using high performa nce SQUID measuring technique, In this review the application of LTS D C SQUIDs with Nb-NbOx-Pb/In/Au window-type Josephson junctions for gra vitational experiments is described, Under optimal conditions a noise limited sensitivity of 1.4 x 10(-12) m/root Hz for the position detect or was achieved corresponding to a flux noise of the SQUID system of 2 x 10(-6) Phi(0)/root Hz. The contribution gives the design of the DC SQUID position detector and summarizes recent results of its applicati on in gravitational experiments.