4,304 research outputs found
Waveguide-based single-pixel up-conversion infrared spectrometer
A periodically poled lithium niobate (PPLN) waveguide-based single-pixel
up-conversion infrared spectrometer was demonstrated. Sum-frequency generation
between a 1.5 micrometer band scanning pump laser and a 1.3 micrometer band
signal generated visible radiation which was detected by a silicon
single-photon detector. The noise equivalent power of the upconversion
spectrometer was two-orders-of-magnitude lower than that of a commercial
optical spectrum analyzer.Comment: 5 pages, 3 figure
The Bose-Einstein distribution functions and the multiparticle production at high energies
The evolution properties of propagating particles produced at high energies
in a randomly distributed environment are studied. The finite size of the phase
space of the multiparticle production region as well as the chaoticity can be
derived.Comment: 18 pages, LaTeX, no figures, no table
X-ray analog pixel array detector for single synchrotron bunch time-resolved imaging
Dynamic x-ray studies may reach temporal resolutions limited by only the
x-ray pulse duration if the detector is fast enough to segregate synchrotron
pulses. An analog integrating pixel array detector with in-pixel storage and
temporal resolution of around 150 ns, sufficient to isolate pulses, is
presented. Analog integration minimizes count-rate limitations and in-pixel
storage captures successive pulses. Fundamental tests of noise and linearity as
well as high-speed laser measurements are shown. The detector resolved
individual bunch trains at the Cornell High Energy Synchrotron Source (CHESS)
at levels of up to 3.7x10^3 x-rays/pixel/train. When applied to turn-by-turn
x-ray beam characterization single-shot intensity measurements were made with a
repeatability of 0.4% and horizontal oscillations of the positron cloud were
detected. This device is appropriate for time-resolved Bragg spot single
crystal experiments.Comment: 9 pages, 11 figure
Simulations of Time-Resolved X-Ray Diffraction in Laue Geometry
A method of computer simulation of Time-Resolved X-ray Diffraction (TRXD) in
asymmetric Laue (transmission) geometry with an arbitrary propagating strain
perpendicular to the crystal surface is presented. We present two case studies
for possible strain generation by short-pulse laser irradiation: (i) a
thermoelastic-like analytic model; (ii) a numerical model including effects of
electron-hole diffusion, Auger recombination, deformation potential and thermal
diffusion. A comparison with recent experimental results is also presented.Comment: 9 pages, 11 figure
Method for Flavor Tagging in Neutral B Meson Decays
A method is proposed for tagging the flavor of neutral mesons in the
study of CP-violating decay asymmetries. The method makes use of a possible
difference in interactions in or systems with isospins 1/2
and 3/2, and would be particularly clean if the systems can be
detected as ``'' resonances.Comment: Submitted to Phys. Rev. D. 11 pages, LaTeX, Technion-PH-92-40 / PITHA
92/39 / EFI 92-5
Like Sign Dilepton Signature for R-Parity Violating SUSY Search at the Tevatron Collider
The like sign dileptons provide the most promising signature for
superparticle search in a large category of -parity violating SUSY models.
We estimate the like sign dilepton signals at the Tevatron collider, predicted
by these models, over a wide region of the MSSM parameter space. One expects an
unambiguous signal upto a gluino mass of GeV ( GeV) with
the present (proposed) accumulated luminosity of .Comment: 12 page LaTeX file; 5 figures available upon request from the autho
Collider discovery limits for supersymmetric Higgs bosons
The prospects for discovery of the five Higgs bosons of the minimal
supersymmetric standard model are assessed for existing and planned future
colliders, including LEP\,I, LEP\,II, LHC and SSC. As a benchmark for
comparisons, we take a top-quark mass GeV and squark mass parameter
TeV in evaluating one-loop radiative corrections; some results
for other values are also given. Searches based on the most promising
production and decay channels are taken into account. For large regions in
parameter space, detectable signals are predicted for one or more of the Higgs
bosons, but there remains a region for which no signals would be visible at the
above colliders.Comment: 24 pages, 23 postscript figures available on request. MAD/PH/69
Picosecond laser-pump, x-ray probe spectroscopy of GaAs
A laser-pump, x-ray probe spectroscopic experiment is described, and the results are shown. The Ga KαKα x-ray fluorescence following x-ray absorption, at the Ga K absorption edge was measured, and its increase due to excitation with subpicosecond pulses of laser light at 4.6 eV photon energy was determined. The x-ray absorption, and thus the fluorescence, is increased for about 200 ps after the laser pulse because additional final states for the x-ray absorption are cleared in the valence band by the laser excitation. The technique could eventually lead to a femtosecond pump-probe spectroscopy with an absolute reference energy level and also to a femtosecond x-ray detector. This is of particular importance to future short-pulse x-ray sources, such as free-electron lasers. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69690/2/RSINAK-73-12-4150-1.pd
Radiative Corrections to Neutralino and Chargino Masses in the Minimal Supersymmetric Model
We determine the neutralino and chargino masses in the MSSM at one-loop. We
perform a Feynman diagram calculation in the on-shell renormalization scheme,
including quark/squark and lepton/slepton loops. We find generically the
corrections are of order 6%. For a 20 GeV neutralino the corrections can be
larger than 20%. The corrections change the region of
parameter space which is ruled out by LEP data. We demonstrate that, e.g., for
a given and the lower limit on the parameter can shift
by 20 GeV.Comment: 11 pages, JHU-TIPAC-930030, PURD-TH-93-13, uses epsf.sty, 6 uuencoded
postscript figures, added one sentence and a referenc
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