221 research outputs found
A battery-operated, stabilized, high-energy pulsed electron gun for the production of rare gas excimers
We report on the design of a new type of electron gun to be used for
experiments of infrared emission spectroscopy of rare gas excimers. It is based
on a filament heated by means of a pack of rechargeable batteries floated atop
the high-voltage power supply. The filament current is controlled by a feedback
circuit including a superluminescent diode decoupled from the high voltage by
means of an optical fiber. Our experiment requires that the charge injection is
pulsed and constant and stable in time. This electron gun can deliver several
tens of nC per pulse of electrons of energy up to keV into the sample
cell. This new design eliminates ripples in the emission current and ensures up
to 12 hrs of stable performance.Comment: 1o pages, 8 figures, to be submitted to Review of Scientific
Instrument
Schroedinger Wheeler-DeWitt Equation In Multidimensional Cosmology
We study multidimensional cosmology to obtain the wavefunction of the
universe using wormhole dominance proposal. Using a prescription for time we
obtain the Schroedinger-Wheeler-DeWitt equation without any reference to WD
equation and WKB ansatz for WD wavefunction. It is found that the
Hartle-Hawking or wormhole-dominated boundary conditions serve as a seed for
inflation as well as for Gaussian type ansatz to Schroedinger-Wheeler-DeWitt
equation.Comment: 10 Pages, LaTeX, no figur
Ultra high level liquid argon purification using electron emission from a tip array
Abstract An array of 148 sharp tips was used to inject large quantities of free electrons in liquid argon and to purify it at a level · 0.09 ppb in few hours. We also evaluated the gettering capability of the stainless steel surface and measured the I–V characteristic of the array
An experimental apparatus for measuring the Casimir effect at large distances
An experimental set-up for the measurement of the Casimir effect at
separations larger than a few microns is presented. The apparatus is based on a
mechanical resonator and uses a homodyne detection technique to sense the
Casimir force in the plane-parallel configuration. First measurements in the
3-10 micrometer range show an unexpected large force probably due to patch
effects.Comment: Proceedings of the workshop On the 60 Years on Casimir Effec
Measurement of the Casimir force between parallel metallic surfaces
We report on the measurement of the Casimir force between conducting surfaces
in a parallel configuration. The force is exerted between a silicon cantilever
coated with chromium and a similar rigid surface and is detected looking at the
shifts induced in the cantilever frequency when the latter is approached. The
scaling of the force with the distance between the surfaces was tested in the
0.5 - 3.0 m range, and the related force coefficient was determined at the
15% precision level.Comment: 4 Figure
Inflation in Multidimensional Quantum Cosmology
We extend to multidimensional cosmology Vilenkin's prescription of tunnelling
from nothing for the quantum origin of the observable Universe. Our model
consists of a -dimensional spacetime of topology , with a scalar field (``chaotic inflaton'') for the
matter component. Einstein gravity and Casimir compactification are assumed.
The resulting minisuperspace is 3--dimensional. Patchwise we find an
approximate analytic solution of the Wheeler--DeWitt equation through which we
discuss the tunnelling picture and the probability of nucleation of the
classical Universe with compactifying extra dimensions. Our conclusion is that
the most likely initial conditions, although they do not lead to the
compactification of the internal space, still yield (power-law) inflation for
the outer space. The scenario is physically acceptable because the inner space
growth is limited to in 100 e-foldings of inflation, starting
from the Planck scale.Comment: RevTeX, 30 pages, 4 figures available via fax on request to
[email protected], submitted to Phys. Rev.
Infrared emission spectrum and potentials of and states of Xe excimers produced by electron impact
We present an investigation of the Xe excimer emission spectrum
observed in the near infrared range about 7800 cm in pure Xe gas and in
an Ar (90%) --Xe (10%) mixture and obtained by exciting the gas with energetic
electrons. The Franck--Condon simulation of the spectrum shape suggests that
emission stems from a bound--free molecular transition never studied before.
The states involved are assigned as the bound state with atomic limit and the dissociative state with limit. Comparison with the spectrum simulated by using theoretical
potentials shows that the dissociative one does not reproduce correctly the
spectrum features.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
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