189 research outputs found
Depinning and dynamics of vortices confined in mesoscopic flow channels
We study the behavior of vortex matter in artificial flow channels confined
by pinned vortices in the channel edges (CE's). The critical current is
governed by the interaction with static vortices in the CE's. We study
structural changes associated with (in)commensurability between the channel
width and the natural row spacing , and their effect on . The
behavior depends crucially on the presence of disorder in the CE arrays. For
ordered CE's, maxima in occur at matching ( integer), while
for defects along the CE's cause a vanishing . For weak CE
disorder, the sharp peaks in at become smeared via nucleation
and pinning of defects. The corresponding quasi-1D row configurations can
be described by a (disordered)sine-Gordon model. For larger disorder and
, levels at of the ideal lattice strength
. Around 'half filling' (), disorder causes new
features, namely {\it misaligned} defects and coexistence of and
rows in the channel. This causes a {\it maximum} in around mismatch,
while smoothly decreases towards matching due to annealing of the
misaligned regions. We study the evolution of static and dynamic structures on
changing , the relation between modulations of and transverse
fluctuations and dynamic ordering of the arrays. The numerical results at
strong disorder show good qualitative agreement with recent mode-locking
experiments.Comment: 29 pages, 32 figure
Probing the nuclide 180W for neutrinoless double-electron capture exploration
The mass difference of the nuclides 180W and 180Hf has been measured with the
Penning-trap mass spectrometer SHIPTRAP to investigate 180W as a possible
candidate for the search for neutrinoless doubleelectron capture. The Q-value
was measured to 143.20(27)keV. This value in combination with the calculations
of the atomic electron wave functions and other parameters results in a
half-life of the 0+ \rightarrow 0+ ground-state to ground-state double-electron
capture transition of approximately 5\cdot10E27 years/^2
Precision Measurement of the First Ionization Potential of Nobelium
One of the most important atomic properties governing an element’s chemical behavior is the energy required to remove its least-bound electron, referred to as the first ionization potential. For the heaviest elements, this fundamental quantity is strongly influenced by relativistic effects which lead to unique chemical properties. Laser spectroscopy on an atom-at-a-time scale was developed and applied to probe the optical spectrum of neutral nobelium near the ionization threshold. The first ionization potential of nobelium is determined here with a very high precision from the convergence of measured Rydberg series to be 6.626 21 ± 0.000 05 eV . This work provides a stringent benchmark for state-of-the-art many-body atomic modeling that considers relativistic and quantum electrodynamic effects and paves the way for high-precision measurements of atomic properties of elements only available from heavy-ion accelerator facilities
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