4,076 research outputs found
Pair Photoproduction in Constant and Homogeneous Electromagnetic Fields
The process of pair creation by a photon in a constant and homogeneous
electromagnetic field of an arbitrary configuration is investigating. At high
energy the correction to the standard quasiclassical approximation (SQA) has
been calculated. In the region of intermediate photon energies where SQA is
inapplicable the new approximation, developed recently by authors, is used. The
influence of weak electric field on the process in a magnetic field is
considered. In particular, in the presence of electric field the root
divergence in the probability of pair creation on the Landau energy levels is
vanished. For smaller photon energies the low energy approximation is used. The
found probability describes the absorption of soft photon by particles created
by field. At low photon energy the electric field action dominates and the
influence of magnetic field on the process is connected with the interaction of
it and the magnetic moment of creating particles.Comment: 11 page
Beam-size effect in Bremsstrahlung
The smallness of the transverse dimensions of the colliding beams leads to
suppression of bremsstrahlung cross section. This beam-size effect was
discovered and investigated at INP, Novosibirsk. Different mechanisms of
radiation are discussed. Separation of coherent and incoherent radiation is
analyzed in detail. For linear collider this suppression affects the whole
radiation spectrum. It is shown that objections to the subtraction procedure in
\cite{BK2} are groundless.Comment: Plenary talk at the Workshop "Quantum Aspects of Beam Physics",
Hiroshima, Japan, January 7-11, 2003. To be pulished in the Proceedings
(World Scientific, Singapore
Coherent and incoherent radiation from high-energy electron and the LPM effect in oriented single crystal
The process of radiation from high-energy electron in oriented single crystal
is considered using the method which permits inseparable consideration of both
coherent and incoherent mechanisms of photon emission. The total intensity of
radiation is calculated. The theory, where the energy loss of projectile has to
be taken into account, agrees quite satisfactory with available CERN data. It
is shown that the influence of multiple scattering on radiation process is
suppressed due to action of crystal field.Comment: 15 pages, 3 figure
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