Search for a permanent EDM in 199Hg
M.V. Romalis, W.C. Griffith, D. Harber, B.R. Heckel, E.N. Fortson (University of Washington), J.P. Jacobs (University of Montana)
The most stringent limit on CP-violating nuclear interactions comes from the search for an Electric Dipole Moment of 199Hg [J.P. Jacobs, et al. Phys. Rev. A 52, 3521, (1995)]. We are working on the next generation of this experiment. The experiment uses a tunable UV laser for optical pumping of Hg at 254 nm. Significant improvements have been made to the detector efficiency and 199Hg vapor cells. Systematic effects are reduced by using the rotation of linearly polarized off-resonant light to detect the spin precession of the Hg atoms. Recently we performed a detailed study of the electric field in the cells using the Stark shift of the 61S0 --> 63P1 Hg transition. We measured, for the first time, the scalar Stark shift of this transition. It is equal to 3.34(6) kHz/(kV/cm2). The accuracy of the Hg atomic theory is presently one of the limiting factors in the interpretation of the EDM limit. If the theory is improved, the Stark shift can be used as a check of the calculations. We are presently accumulating EDM data and checking for systematic errors. A preliminary result on the 199Hg EDM will be reported.
Spontaneous Polarization in Cesium Vapor: Theoretical Modelling and Comparison with Experimental Data
A. Andalkar, R. B. Warrington, M. V. Romalis, B. R. Heckel, E. N. Fortson
Spontaneous atomic spin polarization (SP) is a method for spin polarizing alkali-like atoms using linearly polarized light. Under appropriate conditions, only two stable states of polarization are possible (parallel/antiparallel to an applied magnetic field), and either state can arise spontaneously from any small initial bias. Previous work has demonstrated this effect in a Cs vapor in N2 buffer gas pumped on either the 3 --> 4 or 3 --> 3 hyperfine components of the D1 transition (in the latter case, angular momentum is gained not from the pump light but from the buffer gas during quenching). We have developed a detailed theoretical model of SP, with a density matrix treatment of the buildup of polarization including the effects of excited state coherence and relaxation, diffusion, and ground state relaxation due to Cs-Cs and Cs-N2 collisions. This provides good quantitative agreement with experimental data over a wide range of parameters, such as Cs vapor density, buffer gas pressure, pump light polarization and detuning, and magnetic field magnitude and orientation. The model could be used to explore the feasibility of new experimental situations, such as SP using unpolarized light, which might have applications in the search for a permanent atomic EDM. Further information can be found at http://www.phys.washington.edu/~andalkar/.
| Previous Conference Abstracts: | APS Centennial Meeting, Atlanta, March 1999 |
| ICAP XVI, Windsor, ON, August 1998 | |
| DAMOP Meeting, Santa Fe, May 1998 | |
| APS Meeting, Washington DC, April 1997 |