Low noise LTS SQUIDs for application in gravitational experiments

The Weak Principle of Equivalence (WEP) is proved up to now with an accuracy of 1 x 10(-12). Short range free fall experiments attained an accuracy of 5 x 10(-10) only, Microgravity facilities such as the ''Drop Tower Bremen'' enables long range free fall experiments which may improve the accuracy of free fall tests to < 10(-12) using high performance SQUID measuring technique, In this review the application of LTS DC SQUIDs with Nb-NbOx-Pb/In/Au window-type Josephson junctions for gravitational experiments is described, Under optimal conditions a noise limited sensitivity of 1.4 x 10(-12) m/root Hz for the position detector 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 application in gravitational experiments.