Norval Fortson

Progress on indium and barium single ion optical frequency standards

We report progress on /sup 115/In/sup +/ and /sup 137/Ba/sup +/ single ion optical frequency standards using all solid-state sources. Both are free from quadrupole field shifts and together enable a search for drift in fundamental constants.

SEARCH FOR A PERMANENT ELECTRIC DIPOLE MOMENT ON ATOMS

A number of new experiments searching for a permanent electric dipole moment on atoms and molecules have begun in recent years. We discuss two of these experiments, and present recent results setting upper limits to the dipole moments on Hg and Rb atoms. We also discuss the implications of these results for various theories of T violation, some of which attempt to account for the known CP violation in K o decay. We also present some results from the Hg experiment that establish the most exacting test yet of spatial isotropy.

Parity and time reversal experiments in atoms

There has been exciting progress in recent years in measuring parity nonconservation in atoms as a probe of the fundamental electroweak force, and in searching for a permanent electric dipole moment of atoms and molecules as a test of time reversal symmetry. We are carrying out experiments of each type: a measurement of parity nonconserving optical rotation in atomic lead vapor, and a search for an electric dipole on mercury atoms. We describe both experiments and report our most recent results, including the smallest upper limit to date on an electric dipole moment, ‖ d(199Hg) ‖<2×10−27 ecm, which sets new constraints on possible T‐violating interactions among elementary particles.

Recent experimental T tests

There has been exciting progress in recent years in the search for a permanent electric dipole moment of atoms, molecules, and the neutron. Such a dipole can exist only if time reversal symmetry is violated. We present a brief survey of the current experiments and results, and summarize what they imply about the size of possible T violating interactions among elementary particles. We conclude with a short description of the latest EDM experiment on mercury atoms at the University of Washington, which sets a new upper bound on the dipole moment, d(199Hg)<3×10−27 ecm.

An Optical Rotation Experiment to Search for Neutral Current Effects in Atomic Bismuth

We discuss here the current status of an experiment1,2 at the University of Washington in which we are searching for a small parity non-conserving (PNC) effect in atoms. As first pointed out by Bouchiat and Bouchiat3, effects of measurable size are expected in heavy atoms if the neutral weak current interaction4–6 between electrons and nucleons has a PNC component. In our experiment, the effect of interest is an optical rotation associated with the 8755A magnetic-dipole absorption line in atomic bismuth vapor. Similar experiments have been proposed by Sandars7 and Khriplovich8, and one using the 6476A line in Bi is underway and is being reported at this conference.9