3,758 research outputs found
Periodic-orbit approach to the nuclear shell structures with power-law potential models: Bridge orbits and prolate-oblate asymmetry
Deformed shell structures in nuclear mean-field potentials are systematically
investigated as functions of deformation and surface diffuseness. As the
mean-field model to investigate nuclear shell structures in a wide range of
mass numbers, we propose the radial power-law potential model, V \propto
r^\alpha, which enables a simple semiclassical analysis by the use of its
scaling property. We find that remarkable shell structures emerge at certain
combinations of deformation and diffuseness parameters, and they are closely
related to the periodic-orbit bifurcations. In particular, significant roles of
the "bridge orbit bifurcations" for normal and superdeformed shell structures
are pointed out. It is shown that the prolate-oblate asymmetry in deformed
shell structures is clearly understood from the contribution of the bridge
orbit to the semiclassical level density. The roles of bridge orbit
bifurcations in the emergence of superdeformed shell structures are also
discussed.Comment: 20 pages, 23 figures, revtex4-1, to appear in Phys. Rev.
Zero field spin splitting in AlSb/InAs/AlSb quantum wells induced by surface proximity effects
InAs quantum well heterostructures are of considerable interest for
mesoscopic device applications such as scanning probe and magnetic recording
sensors, which require the channel to be close to the surface. Here we report
on magnetotransport measurements of AlSb/InAs/AlSb Hall bars at a shallow depth
of 20 nm. Analysis of the observed Shubnikov-de Haas oscillations and modeling
show that spin splitting energies in excess of 2.3 meV occur at zero magnetic
field. We conclude that the spin-splitting results from the Rashba effect due
to the band bending in the quantum well. This is caused by substantial electron
transfer from the surface to the quantum well and becomes significant when the
quantum well is located near the surface.Comment: 14 pages, 2 figures. (To be published in APL
Method for detecting coliform organisms
A method and apparatus are disclosed for determining the concentration of coliform bacteria in a sample. The sample containing the coliform bacteria is cultured in a liquid growth medium. The cultured bacteria produce hydrogen and the hydrogen is vented to a second cell containing a buffer solution in which the hydrogen dissolves. By measuring the potential change in the buffer solution caused by the hydrogen, as a function of time, the initial concentration of bacteria in the sample is determined. Alternatively, the potential change in the buffer solution can be compared with the potential change in the liquid growth medium to verify that the potential change in the liquid growth medium is produced primarily by the hydrogen gas produced by the coliform bacteria
Feasibility of mining lunar resources for earth use: Circa 2000 AD. Volume 1: Summary
The feasibility of obtaining lunar minerals for terrestrial uses is examined. Preliminary results gave indications that it will not be economically feasible to mine, refine, and transport lunar materials to Earth for consumption. A broad systems approach was used to analyze the problem. It was determined that even though the procedure was not economically advisable, the concept for the operations is technically sound
Numerical determination of entanglement entropy for a sphere
We apply Srednicki's regularization to extract the logarithmic term in the
entanglement entropy produced by tracing out a real, massless, scalar field
inside a three dimensional sphere in 3+1 flat spacetime. We find numerically
that the coefficient of the logarithm is -1/90 to 0.2 percent accuracy, in
agreement with an existing analytical result
Transmission Phase of an Isolated Coulomb-Blockade Resonance
In two recent papers, O. Entin-Wohlman et al. studied the question: ``Which
physical information is carried by the transmission phase through a quantum
dot?'' In the present paper, this question is answered for an islolated
Coulomb-blockade resonance and within a theoretical model which is more closely
patterned after the geometry of the actual experiment by Schuster et al. than
is the model of O. Entin-Wohlman et al. We conclude that whenever the number of
leads coupled to the Aharanov-Bohm interferometer is larger than two, and the
total number of channels is sufficiently large, the transmission phase does
reflect the Breit-Wigner behavior of the resonance phase shift.Comment: 6 pages and one figur
Fast scintillation counter system and performance
An experimental study of the fast scintillation counter (FS) system to observe a shower disk structure at Mt. Norikura is described, especially the system performance and a pulse wave-form by a single charge particles. The photomultiplier tube (PT) pulse appears at the leading edge of the main pulse. To remove this PT-pulse from the main pulse, the frame of the scintillator vessel was changed. The fast triggering system was made to decrease the dead time which came from the use of the function of the self triggering of the storage oscilloscope (OSC). To provide a new field on the multi-parameter study of the cosmic ray showers, the system response of the FS system also improved as a result of many considerations
The structure of the shower disk observed at Mt. Norikura
The structure of the EAS shower disk, the arrival time distribution of charged particles at the core of the small or middle size shower, is measured at Mt. Norikura in Japan. Four fast scintillation counters with an area of 0.25 sq m and a fast trigger system are added to the Mt. Norikura EAS array for the study
A consideration of the effects of the slip displacement on fretting fatigue behaviour
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