  It is well known that a rotating superconductor produces a magnetic field
proportional to its angular velocity. The authors conjectured earlier, that in
addition to this so-called London moment, also a large gravitomagnetic field
should appear to explain an apparent mass increase of Niobium Cooper-pairs. A
similar field is predicted from Einstein's general relativity theory and the
presently observed amount of dark energy in the universe. An experimental
facility was designed and built to measure small acceleration fields as well as
gravitomagnetic fields in the vicinity of a fast rotating and accelerating
superconductor in order to detect this so-called gravitomagnetic London moment.
This paper summarizes the efforts and results that have been obtained so far.
Measurements with Niobium superconductors indeed show first signs which appear
to be within a factor of 2 of our theoretical prediction. Possible error
sources as well as the experimental difficulties are reviewed and discussed. If
the gravitomagnetic London moment indeed exists, acceleration fields could be
produced in a laboratory environment.
