17,717 research outputs found
Reentrant Melting of Soliton Lattice Phase in Bilayer Quantum Hall System
At large parallel magnetic field , the ground state of bilayer
quantum Hall system forms uniform soliton lattice phase. The soliton lattice
will melt due to the proliferation of unbound dislocations at certain finite
temperature leading to the Kosterlitz-Thouless (KT) melting. We calculate the
KT phase boundary by numerically solving the newly developed set of Bethe
ansatz equations, which fully take into account the thermal fluctuations of
soliton walls. We predict that within certain ranges of , the
soliton lattice will melt at . Interestingly enough, as temperature
decreases, it melts at certain temperature lower than exhibiting
the reentrant behaviour of the soliton liquid phase.Comment: 11 pages, 2 figure
Improved TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems
Scintillation light produced in liquid argon (LAr) must be shifted from 128
nm to visible wavelengths in light detection systems used for liquid argon
time-projection chambers (LArTPCs). To date, LArTPC light collection systems
have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes
(PMTs) or plates placed in front of the PMTs. Recently, a new approach using
TPB-coated light guides was proposed. In this paper, we report on light guides
with improved attenuation lengths above 100 cm when measured in air. This is an
important step in the development of meter-scale light guides for future
LArTPCs. Improvements come from using a new acrylic-based coating,
diamond-polished cast UV transmitting acrylic bars, and a hand-dipping
technique to coat the bars. We discuss a model for connecting bar response in
air to response in liquid argon and compare this to data taken in liquid argon.
The good agreement between the prediction of the model and the measured
response in liquid argon demonstrates that characterization in air is
sufficient for quality control of bar production. This model can be used in
simulations of light guides for future experiments.Comment: 25 pages, 20 figure
Kink-induced transport and segregation in oscillated granular layers
We use experiments and molecular dynamics simulations of vertically
oscillated granular layers to study horizontal particle segregation induced by
a kink (a boundary between domains oscillating out of phase). Counter-rotating
convection rolls carry the larger particles in a bidisperse layer along the
granular surface to a kink, where they become trapped. The convection
originates from avalanches that occur inside the layer, along the interface
between solidified and fluidized grains. The position of a kink can be
controlled by modulation of the container frequency, making possible systematic
harvesting of the larger particles.Comment: 4 pages, 5 figures. to appear in Phys. Rev. Let
Interlayer tunneling in double-layer quantum Hall pseudo-ferromagnets
We show that the interlayer tunneling I--V in double-layer quantum Hall
states displays a rich behavior which depends on the relative magnitude of
sample size, voltage length scale, current screening, disorder and thermal
lengths. For weak tunneling, we predict a negative differential conductance of
a power-law shape crossing over to a sharp zero-bias peak. An in-plane magnetic
field splits this zero-bias peak, leading instead to a ``derivative'' feature
at , which gives a direct measure of
the dispersion of the Goldstone mode corresponding to the spontaneous symmetry
breaking of the double-layer Hall state.Comment: 4 pgs. RevTex, submitted to Phys. Rev. Let
- …