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Search for the permanent electric dipole moment of the electron using cesium
Abstract
The electric dipole moment (edm) of the ground state of cesium has been measured using optical pumping and precision polarization analyzing techniques. The measured value of $d\sb{Cs}$ = ($-$1.8 $\pm$ 6.7 $\pm$ 1.8) $\times$ 10$\sp{-24}e \ cm$ implies that the electron edm $d\sb{e}$ = ($-$1.5 $\pm$ 5.5 $\pm$ 1.5) $\times$ 10$\sp{-26}e \ cm$. This result represents more than an order of magnitude improvement over all previous limits. The basic principle of the experiment is to spin polarize cesium atoms in a cell by optical pumping (along $\vec x$) using a laser tuned to the 6$S\sb{1/2}F$ = 3 $\to$ 6$P\sb{1/2}$ transition (8944 A) in the presence of an electric field $\vec E$ along $\vec z$. The edms oriented along $\vec x$ experience a torque due to the electric field along $\vec z$ and this results in a precession of the initial polarization in the plane perpendicular to $\vec E$. The precessed polarization is detected along $\vec y$ using another laser tuned to the 6$S\sb{1/2}F$ = 4 $\to$ 6$P\sb{1/2}$(8944 A). When the electric field is reversed, the precession is in the opposite sense. The magnetic field is maintained at zero at all times except for calibration. For small angles of precession, the change in the component of the polarization along $\vec y$, denoted by $\Delta P\sb{y}$, when the electric field is reversed is given by$$\Delta P\sb{y} = 2P\sb{x}\omega\sb{E}\tau = 2P\sb{x}\left\lbrack{2d\sb{Cs}E\over (2I + 1)\hbar}\right\rbrack \tau$$ $P\sb{x}$ is the initial polarization along $\vec x$, $\omega\sb{E}$ is the precession frequency due to the electric field, $\tau$ is the characteristic decay time of the polarization and $I$ = $7\over2$ the nuclear spin of the cesium atom. A measurement of such a polarization is thus a measurement of the edm of the cesium atom and the electron edm is derived from $d\sb{Cs} = Rd\sb{e},$ where $R$ the enhancement factor is theoretically calculated to be 120.0 $\pm$ 10.0.
Subject Area
Atomic physics
Recommended Citation
Murthy, Sudha A, "Search for the permanent electric dipole moment of the electron using cesium" (1990). Doctoral Dissertations Available from Proquest. AAI9101650.
https://scholarworks.umass.edu/dissertations/AAI9101650