202 research outputs found
A transportable strontium optical lattice clock
We report on a transportable optical clock, based on laser-cooled strontium
atoms trapped in an optical lattice. The experimental apparatus is composed of
a compact source of ultra-cold strontium atoms including a compact cooling
laser set-up and a transportable ultra-stable laser for interrogating the
optical clock transition. The whole setup (excluding electronics) fits within a
volume of less than 2 m. The high degree of operation reliability of both
systems allowed the spectroscopy of the clock transition to be performed with
10 Hz resolution. We estimate an uncertainty of the clock of .Comment: 12 pages, 9 figures, to be published in Appl. Phys.
A compact and efficient strontium oven for laser-cooling experiments
Here we describe a compact and efficient strontium oven well suited for
laser-cooling experiments. Novel design solutions allowed us to produce a
collimated strontium atomic beam with a flux of 1.0\times10^13 s^-1 cm^-2 at
the oven temperature of 450 {\deg}C, reached with an electrical power
consumption of 36 W. The oven is based on a stainless-steel reservoir, filled
with 6 g of metallic strontium, electrically heated in a vacuum environment by
a tantalum wire threaded through an alumina multi-bore tube. The oven can be
hosted in a standard DN40CF cube and has an estimated continuous operation
lifetime of 10 years. This oven can be used for other alkali and alkaline earth
metals with essentially no modifications.Comment: 6 pages, 6 figures, Review of Scientific Instruments, in pres
Study of coupled states for the (4s^{2})^{1}S + (4s4p)^{3}P asymptote of Ca_{2}
The coupled states A^{1}\Sigma_{u}^{+} (^{1}D +}1}S), c^{3}\Pi_{u} (^{3}P +
^{1}S) and a^{3}\Sigma_{u}^{+} (^{3}P +}1}S) of the calcium dimer are
investigated in a laser induced fluorescence experiment combined with
high-resolution Fourier-transform spectroscopy. A global deperturbation
analysis of the observed levels, considering a model, which is complete within
the subspace of relevant neighboring states, is performed using the Fourier
Grid Hamiltonian method. We determine the potential energy curve of the
A^{1}\Sigma_{u}^{+} and c^{3}\Pi_{u} states and the strengths of the couplings
between them. The c^{3}\Pi_{u} and \as states are of particular importance for
the description of collisional processes between calcium atoms in the ground
state ^{1}S_{0} and excited state ^{3}P_{1} applied in studies for establishing
an optical frequency standard with Ca.Comment: 15 pages, 12 figure
Long range transport of ultra cold atoms in a far-detuned 1D optical lattice
We present a novel method to transport ultra cold atoms in a focused optical
lattice over macroscopic distances of many Rayleigh ranges. With this method
ultra cold atoms were transported over 5 cm in 250 ms without significant atom
loss or heating. By translating the interference pattern together with the beam
geometry the trap parameters are maintained over the full transport range.
Thus, the presented method is well suited for tightly focused optical lattices
that have sufficient trap depth only close to the focus. Tight focusing is
usually required for far-detuned optical traps or traps that require high laser
intensity for other reasons. The transport time is short and thus compatible
with the operation of an optical lattice clock in which atoms are probed in a
well designed environment spatially separated from the preparation and
detection region.Comment: 14 pages, 6 figure
Transport of a quantum degenerate heteronuclear Bose-Fermi mixture in a harmonic trap
We report on the transport of mixed quantum degenerate gases of bosonic 87Rb
and fermionic 40K in a harmonic potential provided by a modified QUIC trap. The
samples are transported over a distance of 6 mm to the geometric center of the
anti-Helmholtz coils of the QUIC trap. This transport mechanism was implemented
by a small modification of the QUIC trap and is free of losses and heating. It
allows all experiments using QUIC traps to use the highly homogeneous magnetic
fields that can be created in the center of a QUIC trap and improves the
optical access to the atoms, e.g., for experiments with optical lattices. This
mechanism may be cascaded to cover even larger distances for applications with
quantum degenerate samples.Comment: 7 pages, 8 figure
Plant mechanosensitive ion channels: an ocean of possibilities
Mechanosensitive ion channels, transmembrane proteins that directly couple mechanical stimuli to ion flux, serve to sense and respond to changes in membrane tension in all branches of life. In plants, mechanosensitive channels have been implicated in the perception of important mechanical stimuli such as osmotic pressure, touch, gravity, and pathogenic invasion. Indeed, three established families of plant mechanosensitive ion channels play roles in cell and organelle osmoregulation and root mechanosensing - and it is likely that many other channels and functions await discovery. Inspired by recent discoveries in bacterial and animal systems, we are beginning to establish the conserved and the unique ways in which mechanosensitive channels function in plants
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente
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