110 research outputs found
Soft Photons in Hadron-Hadron Collisions: Synchrotron Radiation from the QCD Vacuum?
We discuss the production of soft photons in high energy hadron-hadron
collisions. We present a model where quarks and antiquarks in the hadrons emit
``synchrotron light'' when being deflected by the chromomagnetic fields of the
QCD vacuum, which we assume to have a nonperturbative structure. This gives a
source of prompt soft photons with frequencies in the c.m.
system of the collision in addition to hadronic bremsstrahlung. In comparing
the frequency spectrum and rate of ``synchrotron'' photons to experimental
results we find some supporting evidence for their existence. We make an
exclusive--inclusive connection argument to deduce from the ``synchrotron''
effect a behaviour of the neutron electric formfactor proportional
to for . We find this to be consistent with
available data. In our view, soft photon production in high energy
hadron-hadron and lepton-hadron collisions as well as the behaviour of
electromagnetic hadron formfactors for low are thus sensitive probes of
the nonperturbative structure of the QCD vacuum.Comment: Heidelberg preprint HD-THEP-94-36, 31 pages, LaTeX + ZJCITE.sty
(included), 12 figures appended as uuencoded compressed ps-fil
Elastic Mid-Infrared Light Scattering: a Basis for Microscopy of Large-Scale Electrically Active Defects in Semiconducting Materials
A method of the mid-IR-laser microscopy has been proposed for the
investigation of the large-scale electrically and recombination active defects
in semiconductors and non-destructive inspection of semiconductor materials and
structures in the industries of microelectronics and photovoltaics. The basis
for this development was laid with a wide cycle of the investigations on the
low-angle mid-IR-light scattering in semiconductors. The essence of the
technical idea was to apply the dark-field method for spatial filtering of the
scattered light in the scanning mid-IR-laser microscope. This approach enabled
the visualization of large-scale electrically active defects which are the
regions enriched with ionized electrically active centers. The photoexcitation
of excess carriers within a small volume located in the probe mid-IR-laser beam
enabled the visualization of the large-scale recombination-active defects like
those revealed in the optical or electron beam induced current methods. Both
these methods of the scanning mid-IR-laser microscopy are now introduced in
detail in the present paper as well as a summary of techniques used in the
standard method of the lowangle mid-IR-light scattering itself. Besides the
techniques for direct observations, methods for analyses of the defect
composition associated with the mid-IR-laser microscopy are also discussed in
the paper.Comment: 44 pages, 13 figures. A good oldi
Attenuated and Protease-Profile Modified Sendai Virus Vectors as a New Tool for Virotherapy of Solid Tumors
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