General Relativity Accuracy Test (GReAT): new configuration for the differential accelerometer

We presents the results of an activity concerning the test of the Einstein Weak Equivalence Principle with an accuracy of about 5 x 10^-15. The experiment will be performed in an "Einstein elevator" using a differential accelerometer with a final sensitivity of about 10^-14 g/Hz^1/2. The differential accelerometer is spun about an horizontal axis at a frequency in the range 0.5-1 Hz in order to modulate, during the free fall, the signal from a possible violation of the Equivalence Principle. In the paper the perturbing effects with the same signature of the possible violation are analyzed and constrained. The experimental results obtained in the laboratory with a first prototype of the differential accelerometer are discussed, comparing this results with those obtained using a new prototype.