Visit to GEO600 - Report

By Kris Schroven, PhD candidate RTG "Models of Gravity"

Located in the countryside in Ruthe, close to Hanover, is the gravitational wave detector GEO600. On one of the first spring like days this year we (the RTG fellows) had the chance to pay a visit. Here is what we saw and learned from it. 

Supernovae or coalescing massive binaries, may it be neutron stars or black holes, are astronomical mega events, which create such strong gravitational waves, that they are still measurable on earth as extremely small, periodic distorions in spacetime. Exactly for this purpose GEO600 was built. Gravitational waves were predicted by Albert Einstein 1916 as solutions to his field equations. It was only last year, almost 100 years later, that these distortions were directly detected for the very first time by two LIGO gravitational wave detectors located in the USA. This fact made it particularly exciting for our group of PhD candidates to visit such a detector in Germany which is a Michelson interferometer with 600 m long arms.                                                                           Although being a much smaller colleague than his American relatives, who sport arms with 4 kilometers lengths, the GEO600 has made up for this disadvantage with a more sophisticated technology, e.g. its laser system and mirror suspension.
However, it should be noted here that eventually, both developments have been playing a leading role in last year's findings of the gravitational waves. The reason for this is that while reconstructing the LIGO detectors in the USA, by this becoming the Advanced LIGO, the GEO600 developments have been implemented. 

From the exterior GEO600 looks rather low-key as we drove on a small road along one of the interferometer arms and a small tree nursery for apple trees to the main part of the facility. The interferometer arm was at first not recognized by us as what it was, since it looked more like some kind of cable channel of pipeline. At heart of the facility are just three container huts, which contain the control room, the workplaces for the scientists on site and the central building of GEO600. But during our two hours visitors' tour we were able to look behind the unobtrusive outside walls of GEO600 and gained interesting insights into the construction and function of the wave detector. While talking and waiting in the sun for our taxis back to Sarstedt station some more nice little facts about GEO600 were revealed, e.g.: Every earthquake on earth with a magnitude of seven or higher shuts down the detector for hours.                                                                          

At around 6 pm our excursion led us back to Hanover main station where we spent the night in order to attend our RTG colloquium at the University of Hanover the following morning.
We enjoyed our visit the GEO600 and their friendly staff a lot and would like to thank them - especially Benjamin Knispel - to make this trip possible for us.