Superconducting Gravimeter

Prior to the installation at SAGOS the Single Sphere Superconducting Gravimeter T018, which had been in operation at the GFZ Potsdam site from 1992 to 1998, was upgraded by the company "GWR instruments". The Gravity Sensing Unit (GSU) was replaced by a Dual Sphere Unit with two gravity sensors. The sensors have a distance of 19.63 cm. Additionally, the electronic measuring equipment and the data acquisition system with GPS time keeping were upgraded. For continuous gravity measurements the dewar which is housing the GSU was bottom-mounted on top of the pillar in the temperature-controlled measurement room. The coldhead was fastened to a frame fixed on the wall of the room. Compressor and coolpack were put in a separate room.

End of July / beginning of August 2008 the gravimeter was replaced by a new instrument, the SG 052. The exchange became necessary due to an instrument-related diminished data quality. The new gravimeter contains only one sensor unit, but has an integrated system for helium liquification. Thus regular liquid helium refills have become redundant which led to major disturbances in the gravity record in the past and were quite laborious.