177 research outputs found
Collective Atomic Motion in an Optical Lattice formed inside a High Finesse Cavity
We report on collective non-linear dynamics in an optical lattice formed
inside a high finesse ring cavity in a so far unexplored regime, where the
light shift per photon times the number of trapped atoms exceeds the cavity
resonance linewidth. We observe bistability and self-induced squeezing
oscillations resulting from the retro-action of the atoms upon the optical
potential wells. We can well understand most of our observations within a
simplified model assuming adiabaticity of the atomic motion. Non-adiabatic
aspects of the atomic motion are reproduced by solving the complete system of
coupled non-linear equations of motion for hundred atoms.Comment: 4 pages, 5 figure
Collective Sideband Cooling in an Optical Ring Cavity
We propose a cavity based laser cooling and trapping scheme, providing tight
confinement and cooling to very low temperatures, without degradation at high
particle densities. A bidirectionally pumped ring cavity builds up a resonantly
enhanced optical standing wave which acts to confine polarizable particles in
deep potential wells. The particle localization yields a coupling of the
degenerate travelling wave modes via coherent photon redistribution. This
induces a splitting of the cavity resonances with a high frequency component,
that is tuned to the anti-Stokes Raman sideband of the particles oscillating in
the potential wells, yielding cooling due to excess anti-Stokes scattering.
Tight confinement in the optical lattice together with the prediction, that
more than 50% of the trapped particles can be cooled into the motional ground
state, promise high phase space densities.Comment: 4 pages, 1 figur
First limits on double beta decays in Th
As one of the primordial radioactive isotopes, Th mainly undergoes
-decay with a half-life of yr. However, it is
also one of 35 double beta decay candidates in which the single -decay
is forbidden or strongly suppressed. 181 mg of thorium contained in a gas
mantle was measured in an HPGe well-detector at the Gran Sasso Underground
Laboratory (LNGS) with a total exposure of 3.25 g d. We obtain
half-life limits on all double beta decay modes of Th to excited states
of U on the order of yr. For the most likely transition
into the state we find a lower half-life limit of
yr (90% credibility). These are the first constraints on double beta decay
excited state transition in Th
On the possibility to search for double beta decay of initially unstable (alpha/beta radioactive) nuclei
Possibilities to search for double beta decay of alpha/beta unstable nuclei,
many of which have higher energy release than "conventional" (beta stable)
double beta decay candidates, are discussed. First experimental half-life
limits on double beta decay of radioactive nuclides from U and Th families
(trace contaminants of the CaWO_4, CdWO_4 and Gd_2SiO_5 scintillators) were
established by reanalyzing the data of low-background measurements in the
Solotvina Underground Laboratory with these detectors (1734 h with CaWO_4,
13316 h with CdWO_4, and 13949 h with Gd_2SiO_5 crystals).Comment: 15 pages, 6 figure
A new investigation of half-lives for the decay modes of V
A new search for the decay modes of the 4-fold forbidden non-unique decay of
V has been performed at the Gran Sasso Underground Laboratory (LNGS). In
total an exposure of 197 kg d has been accumulated. The half-life for
the electron capture into the first excited state of Ti has been
measured with the highest precision to date as yr (68% C.I.) in which systematics uncertainties dominate. The search
for the -decay into the first excited state of Cr resulted in a
lower limit of yr (90% C.I.), which is an improvement of
almost one order of magnitude compared to existing results. The sensitivity of
the new measurement is now in the region of theoretical predictions
Updated and novel limits on double beta decay and dark matter-induced processes in platinum
A 510 day long-term measurement of a 45.3 g platinum foil acting as the
sample and high voltage contact in an ultra-low-background high purity
germanium detector was performed at Laboratori Nazionali del Gran Sasso
(Italy). The data was used for a detailed study of double beta decay modes in
natural platinum isotopes. Limits are produced in the range
a for double beta decay to excited states (90%
C.L.) confirming, and partially extending existing limits. The highest
sensitivity, greater than a, was achieved for the and resonant
modes of double electron capture involving KL shell electrons.
Additionally, novel limits for inelastic dark matter scattering on Pt
are placed up to mass splittings of approximately 500 keV. We analyze several
techniques to extend the sensitivity and propose a few approaches for future
medium-scale experiments with platinum-group elements.Comment: 15 pages, 3 figure
Cold atoms in a high-Q ring-cavity
We report the confinement of large clouds of ultra-cold 85-Rb atoms in a
standing-wave dipole trap formed by the two counter-propagating modes of a
high-Q ring-cavity. Studying the properties of this trap we demonstrate loading
of higher-order transverse cavity modes and excite recoil-induced resonances.Comment: 4 pages, 4 figure
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