NEW EXPERIMENTAL LIMITS TO THE TIME VARIATIONS OF G(P)(M(E) M(P)) ANDALPHA

A new experimental limit to the possible time variation of the proton gyromagnetic ratio times the electron-to-proton mass ratio has been ob tained from the frequency comparison data between Cs and Mg atomic bea m standards. The measurements, made over a period of one year, lead to an upper limit for the rate of change of g(p)(m(e)/m(p)) of 5.4 x 10( -13)/yr. This result, based only on the validity of the quantum mechan ical theory of the atomic spectra, together with astrophysical data re garding analogous products of atomic fundamental constants, leads also to a new limit for the time stability of the fine structure constant a (2.7 x 10(-13)/yr).