The cesium 6 2 S 1/2 scalar dipole polarizability α 0 has been determined from the time-of-flight of laser cooled and launched cesium atoms traveling through an electric field. We find α 0 = 6.611 ± 0.009 × 10 −39 Cm 2 /V = 59.42 ± 0.08 × 10 −24 cm 3 = 401.0 ± 0.6 a 3 0 . The 0.14% uncertainty is a factor of fourteen improvement over the previous measurement. Values for the 6 2 P 1/2 and 6 2 P 3/2 lifetimes and the 6 2 S 1/2 cesium-cesium dispersion coefficient C 6 are determined from α 0 using the procedure of Derevianko and Porsev [Phys. Rev. A 65, 053403 (2002)].PACS numbers: 32.10. Dk,32.60.+i,32.70.Cs The static polarizability quantifies the effect of one of the simplest perturbations to an atom: the application of a static electric field inducing a dipole moment [1,2]. With increasing atomic number, relativistic effects [3,4] and core electron contributions [5,6] to the alkali polarizabilities become increasingly significant. In cesium, the heaviest stable alkali, the relativistic effects reduce the polarizability by 16% and the core contributes 4%. However, experimental uncertainties have made the measurements of the alkali polarizabilities relatively insensitive to the smaller core contribution, as shown in Fig 1. With the largest relativistic correction and core contribution of the stable alkali atoms, the cesium polarizability is an ideal benchmark for testing the theoretical treatment of both relativistic effects and core contributions. Our measurement advances the accuracy of the cesium polarizability by a factor of fourteen over the previous measurement [7] and places the uncertainty at 4% of the core contribution. [8] and [7], respectively, and (c) is this work. The contribution to the polarizability from the core electrons is expected to be smaller in Li than in Na. * Electronic address: JAMaddi@lbl.gov; Also at Physics Department, University California at Berkeley, Berkeley, CA 94720. † Electronic address: Gould@lbl.gov To our measurement's level of accuracy, the hyperfine levels of the cesium ground state have a common polarizability α 0 . From angular momentum relations [9], the dependencies of the polarizability on the hyperfine level F and on the magnetic sublevel M F are greatly suppressed in the cesium ground state. The small remaining dependencies, generated by the hyperfine interaction, have been measured in Refs. [10,11,12].For a static electric field E of moderate strength, the potential energy W of a neutral cesium atom in that field may be written in terms of α 0 as W = −(1/2)α 0 E 2 . All odd terms in E are disallowed by parity conservation and the linear term, also forbidden by time-reversal invariance, is experimentally known to be less than 1.6 × 10 −44 C-m in cesium [13]. The hyperpolarizability contribution, which scales as E 4 , has been calculated [14,15] and is negligible at the fields used for our measurement.Prior to the interferometric measurement of Ekstrom et. al. [8], the most accurate determinations of the alkali polarizabilities [7,16] had been made by measuring t...
