We have observed high-order quantum resonances in a realization of the quantum delta-kicked rotor, using Bose-condensed Na atoms subjected to a pulsed standing wave of laser light. These resonances occur for pulse intervals that are rational fractions of the Talbot time, and are characterized by ballistic momentum transfer to the atoms. The condensate's narrow momentum distribution not only permits the observation of the quantum resonances at 3/4 and 1/3 of the Talbot time, but also allows us to study scaling laws for the resonance width in quasimomentum and pulse interval.

We have measured the hyperfine structure of the 7P 1͞2 level for 2082212 Fr to a precision of 300 ppm. These measurements along with previous ground state hyperfine structure measurements reveal a hyperfine anomaly. The hyperfine anomaly exhibits a strong sensitivity to the radial distribution of the neutron magnetization, providing a good way to probe this quantity. We use neutron radial distributions from recent theories to qualitatively explain the measurements. PACS numbers: 21.10.Gv, 27.80. + w, 32.10.Fn One of the properties of nuclei that can be probed with precise measurements of hyperfine structure is the nuclear magnetization distribution. The Bohr-Weisskopf effect [1,2] has been known for many years, but experimental and theoretical advances have now allowed more broadly based and detailed investigations [3][4][5][6]. There is much interest in obtaining the structural details of heavy nuclei, as these nuclei are involved in understanding quantum electrodynamic (QED) effects in heavy atoms [7], atomic parity nonconservation (PNC), time reversal violation, and nuclear anapole moments [8]. We have measured five different Fr isotopes. Comparison of adjacent isotopes allows extraction of the nuclear magnetization distribution of the last neutron, a quantity that is, in general, very difficult to study [9].Bohr-Weisskopf effect measurements usually require detailed knowledge of both hyperfine structure constants and magnetic moments. We show in this Letter that precision measurements of the hyperfine structure in atomic states with different radial distributions can give information on the hyperfine anomaly [10] and be sensitive to the nuclear magnetization distribution. Laser trapped radioactive atoms, cooled to mK temperatures, are an ideal sample for high precision Doppler-free laser spectroscopy [8]. High precision allows searching for higher order effects in the hyperfine structure.Francium is an excellent element for understanding the atom-nucleus hyperfine interactions, and eventually weak interactions. First, because of the large Z, hyperfine effects proportional to Z 3 are larger than in lighter atoms. Second, the simple atomic structure allows ab initio calculations of its properties [11][12][13]] that have been experimentally tested [14]. Third, Fr has a large number of isotopes spanning almost 30 neutrons with lifetimes greater than 1 s that cover a wide range of nuclear structure. Fourth, because of its proximity to Pb, where the charge radii are known extremely well from many techniques [15], we can determine the charge radii of the light Fr isotopes with some confidence.Coc et al. [16,17] measured the 7S 1͞2 ground state hyperfine constants for 16 Fr isotopes, but only one magnetic moment has been measured [18]. We have focused on extracting hyperfine anomaly information using the available data in the literature and our new precision spectroscopy of the 7P 1͞2 hyperfine structure on five francium isotopes. Previous measurements of the 7P 1͞2 [17] were not of sufficient precision to observe...

We report optical double-resonance spectroscopy to locate and study the 7D 3/2 and 7D 5/2 levels of a sample of 210 Fr atoms confined and cooled in a magneto-optical trap. The upper state of the 7 P 3/2 trapping transition serves as the resonant intermediate level to reach the 7D states. The energy difference to the ground state is measured for the accessible levels. We measure the hyperfine splittings: ⌬(7D 3/2 ,Fϭ15/2↔13/2)ϭ167 Ϯ4 MHz, ⌬(7D 5/2 ,Fϭ17/2↔15/2)ϭϪ117.5Ϯ2.5 MHz, and ⌬(7D 5/2 ,Fϭ15/2↔13/2)ϭϪ121Ϯ4 MHz. Extrapolating the energies of the inaccessible hyperfine levels from the hyperfine constants and assuming B(7D 3/2 )ϭ0, the center-of-gravity energy difference to the ground state is E(7D 3/2 )ϭ24 244.831 Ϯ0.003 cm Ϫ1 and E(7D 5/2 )ϭ24 333.298Ϯ0.003 cm Ϫ1 .