Prospects of laser cooling in atomic thallium

Abstract

One of the most precisely determined upper limits for the electron electric dipole moment (EDM) is set by the thallium (Tl) atomic beam experiment. One way to enhance the sensitivity of the atomic beam setup is to laser cool the Tl atoms to reduce the EDM-like phase caused by the E$\ifmmode\times\else\texttimes\fi{}$v effect. In this report, a cooling scheme based on the $6{P}_{3/2}(F=2)\ensuremath{\leftrightarrow}6{D}_{5/2}({F}^{\ensuremath{'}}=3)$ transition in Tl is proposed. The absolute frequency measurement of this nearly closed-cycle transition was performed in an atomic beam apparatus. Two Ti:sapphire lasers were frequency-doubled using enhancement cavities in X-type configurations to provide the needed 377- and 352-nm light sources for the optical pumping and cooling transitions, respectively. The absolute frequency of this cooling transition is determined to be 851 634 646(56) MHz.