The experiment presented in this thesis has been designed to test Newton’s law of gravitation in the limit of small accelerations caused by weak gravitational forces. It is located at DESY, Hamburg, and is a modification of an experiment that was carried out in Wuppertal, Germany, until 2002 in order to measure the gravitational constant G. The idea of testing Newton’s law in the case of small acclerations emerged from the question whether the flat rotation curves of spiral galaxies can be traced back to Dark Matter or to a law of gravitation that deviates from Newton on cosmic scales like e.g. MOND (Modified Newtonian Dynamics).
The core of this experiment is a microwave resonator which is formed by two spherical concave mirrors that are suspended as pendulums. Masses between 1 and 9 kg symmetrically change their distance to the mirrors from far to near positions. Due to the increased gravitational force the mirrors are pulled apart and the length of the resonator increases. This causes a shift of the resonance frequency which can be translated into a shift of the mirror distance. The small masses are sources of weak gravitational forces and cause accelerations on the mirrors of about 10−10 m/s2. These forces are comparable to those between stars on cosmic scales and the accelerations are in the vicinity of the characteristic acceleration of MOND a0 ≈ 1.2·10−10 m/s2, where deviations from Newton’s law are expected. Thus Newton’s law could be directly checked for correctness under these conditions.
First measurements show that due to the sensitivity of this experiment many systematic influences have to be accounted for in order to get consistent results. Newton’s law has been confirmed with an accuracy of 3%. MOND has also been checked. The interpolation function presented in [Bek05] respectively [Cap09] can be excluded. In order to be able to distinguish Newton from MOND with other interpolation functions the accuracy of the experiment has to be improved.