STATIC TEST FOR A GRAVITATIONAL FORCE COUPLED TO TYPE-II YBCO SUPERCONDUCTORS

As a Bose condensate, superconductors provide novel conditions for rev isiting previously proposed couplings between electromagnetism and gra vity. Strong variations in Cooper pair density, large conductivity and low magnetic permeability define superconductive and degenerate conde nsates without the traditional density limits imposed by the Fermi ene rgy (similar to 10(-6) g cm(3)). Recent experiments have reported anom alous weight loss for a test mass suspended above a rotating type II, YBCO superconductor, with the percentage change (0.05-2.1%) independen t of the test mass' chemical composition and diamagnetic properties. A variation of 5 parts per 10(4) was reported above a stationary (non-r otating) superconductor. In experiments using a sensitive gravimeter, bulk YBCO superconductors were stably levitated in a DC magnetic field . Changes in acceleration were measured to be less than 2 parts in 10( 8) of the normal gravitational acceleration. This result puts new limi ts on the strength and range of the proposed coupling between static s uperconductors and gravity. (C) 1997 Elsevier Science B.V.