1,031 research outputs found
Lifetime determination of the 5d~F state in barium using trapped atoms
Magneto-optically trapped atoms enable the determination of lifetimes of
metastable states and higher lying excited states like the
state in barium. The state is efficiently populated by
driving strong transitions from metastable states within the cooling cycle of
the barium MOT. The lifetime is inferred from the increase of MOT fluorescence
after the transfer of up to of the trapped atoms to this state. The
radiative decay of the state cascades to the cooling
cycle of the MOT with a probability of corresponding to a trap
loss of and its lifetime is determined to .
This is in good agreement with the theoretically calculated lifetime of
[J. Phys. B, {\bf 40}, 227 (2007)]. The determined loss of
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 multi-electron systems.Comment: 5 pages, accepted for publication in Physical Review
Scattering lengths of calcium and barium isotopes
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.Comment: 4 page
Isotope shifts of 6s5d D-states in neutral Barium
Laser spectroscopy of the low lying P and D states in atomic barium
has been performed. This work contributes substantially to the development of
an effective laser cooling and trapping for heavy alkaline earth elements and
aims in particular for a better understanding of the atomic wave function of
these systems. Isotope shifts and hyperfine structures are ideal probes for the
wave functions at the position of the nucleus. This is essential input for a
theoretical evaluation of the sensitivity to fundamental symmetry breaking
properties like permanent electric dipole moments. We report the first isotope
shift measurements of the D-P transitions. A deviation of
the King plot from its expected behavior has been observed. Further we have
optically resolved the hyperfine structure of the D states.Comment: 7 pages, 7 figure
Magneto optical trapping of Barium
First laser cooling and trapping of the heavy alkaline earth element barium
has been achieved based on the strong 6s S - 6s6p P
transition for the main cooling. Due to the large branching into metastable
D-states several additional laser driven transitions are required to provide a
closed cooling cycle. A total efficiency of for slowing
a thermal atomic beam and capturing atoms into a magneto optical trap was
obtained. Trapping lifetimes of more than 1.5 s were observed. This lifetime is
shortened at high laser intensities by photo ionization losses. The developed
techniques will allow to extend significantly the number of elements that can
be optically cooled and trapped.Comment: 4 pages, 5 figure
Absolute frequency measurement of the 7s S 7s7p P transition in Ra
Transition frequencies were determined for transitions in Ra in an atomic
beam and for reference lines in Te molecules in a vapor cell. The absolute
frequencies were calibrated against a GPS stabilized Rb-clock by means of an
optical frequency comb. The 7s^2\,^1S(F = 1/2)-7s7p\,^1P(F = 3/2)
transition in Ra was determined to be 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.Comment: Accepted for publication in the rapid communication of Physical
review
Radium single-ion optical clock
We explore the potential of the electric quadrupole transitions
7s\,^2S_{1/2} - 6d\,^2D_{3/2}, 6d\,^2D_{5/2} in radium isotopes as
single-ion optical frequency standards. The frequency shifts of the clock
transitions due to external fields and the corresponding uncertainties are
calculated. Several competitive Ra candidates with 223 - 229 are
identified. In particular, we show that the transition
7s\,^2S_{1/2}\,(F=2,m_F=0) - 6d\,^2D_{3/2}\,(F=0,m_F=0) at 828 nm in
Ra, with no linear Zeeman and electric quadrupole shifts, stands
out as a relatively simple case, which could be exploited as a compact, robust,
and low-cost atomic clock operating at a fractional frequency uncertainty of
. With more experimental effort, the Ra clocks
could be pushed to a projected performance reaching the level.Comment: 20 pages, 1 figur
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