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Magneto-optically trapped atoms enable the determination of lifetimes of metastable states and higher lying excited states like the 5d² ³F2 state in barium. The state is efficiently populated by driving strong transitions from metastable states within the cooling cycle of the barium magneto-optical trap (MOT). The lifetime is inferred from the increase of MOT fluorescence after the transfer of up to 30% of the trapped atoms to this state. The radiative decay of the 5d² ³F2 state cascades to the cooling cycle of the MOT with a probability of 96.0(7)% corresponding to a trap loss of 4.0(7)% and its lifetime is determined to 160(10) µs. This is in good agreement with the theoretically calculated lifetime of 190 µs [V. A. Dzuba and V. V. Flambaum, J. Phys. B 40, 227 (2007)]. The determined loss of 4.0(7)% from the cooling cycle is compared with the theoretically calculated branching ratios. This measurement extends the efficacy of trapped atoms to measure lifetimes of higher, long-lived states and validate the atomic structure calculations of heavy multielectron systems. [ABSTRACT FROM AUTHOR]

Transition frequencies were determined for transitions in Ra in an atomic beam and for reference lines in Te2 molecules in a vapor cell. The absolute frequencies were calibrated against a GPS stabilized Rb clock by means of an optical frequency comb. The 7s² ¹S0(F = 1/2)-7s7p ¹P1(F = 3/2) transition in 225Ra was determined to be 621042124(2)MHz. The measurements provide input for designing efficient and robust laser cooling of Ra atoms in preparation of a search for a permanent electric dipole moment in Ra isotopes. [ABSTRACT FROM AUTHOR]

We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba) in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca does not provide other isotopes alternative to the recently Bose condensed 40Ca that suffers strong losses because of a very large scattering length. For Ba we show by using a model potential that the even isotopes cover a broad range of scattering lengths, opening the possibility of BEC for at least one of the isotopes. [ABSTRACT FROM AUTHOR]

Laser excitation of the 4s4p 3P2 - 4s3d 1D2 transition in atomic calcium has been observed and the wavelength determined to 1530.5298(6) nm. The metastable 4s4p 3P2 atoms were magnetically trapped in the quadrupole magnetic field of a magneto-optical trap. This state represents the only "loss" channel for the calcium atoms when laser cooled on the 4s2 1S0 - 4s4p 1P1 transition. A rate equation model shows that an order of magnitude more atoms are trapped in this state compared with those taking part in the main cooling cycle. Excitation of the 3P2 atoms back up to the 4s3d 1D2 state provides a means of accessing these atoms. Efficient repumping is achieved if the 1530-nm laser is used in conjunction with a 672-nm laser driving the 4s3d 1D2 - 4s5p 1P1 transition. In the present experiment, we detected about 4.5 × 104 trapped 3P2 atoms, a relatively low atom density, and measured a lifetime of approximately 1 s, which is limited by background collisions. [ABSTRACT FROM AUTHOR]

The frequency dependent polarizabilities of the francium atom are calculated from the available data of energy levels and transition rates. Magic wavelengths for the state insensitive optical dipole trapping are identified from the calculated light shifts of the 7s ²S1/2, 7p ²P1/2,3/2, and 8s ²S1/2 levels of the 7s ²S1/2-7p ²P1/2,3/2 and 7s ²S1/2-8s ²S1/2 transitions, respectively. Wavelengths in the ultraviolet, visible, and near infrared region are identified that are suitable for cooling and trapping. Magic wavelengths between the 600-700 nm and 700-1000 nm regions, which are blue and red detuned with the 7s-7p and 7s-8s transitions, are feasible to implement as lasers with sufficient power are available. In addition, we calculated the tune-out wavelengths where the ac polarizability of the ground 7s ²S1/2 state in francium is zero. These results are beneficial as laser cooled and trapped francium has been in use for fundamental symmetry investigations like searches for an electron permanent electric dipole moment in an atom and for atomic parity nonconservation. [ABSTRACT FROM AUTHOR]

Laser spectroscopy of short-lived radium isotopes in a linear Paul trap has been performed. The isotope shifts of the 6d 2D3/2 -7p 2P1/2 transition in 209-214Ra+, which are sensitive to the short-range part of the atomic wave functions, were measured. The results are essential experimental input for improving the precision of atomic structure calculations. This is indispensable for parity violation in Ra+ aiming at the determination of the weak mixing angle. [ABSTRACT FROM AUTHOR]