18 research outputs found
Coulomb effects in high-energy electroproduction by a heavy charged particles in an atomic field
The cross section of high-energy pair production by a heavy charged
particle in the atomic field is investigated in detail. We take into account
the interaction with the atomic field of pair and a heavy particle as
well. The calculation is performed exactly in the parameters of the atomic
field. It is shown that, in contrast to the commonly accepted point of view,
the cross section differential with respect to the final momentum of a heavy
particle is strongly affected by the interaction of a heavy particle with the
atomic field. However, the cross section integrated over the final momentum of
a heavy particle is independent of this interaction.Comment: 10 pages, 4 figure
Small-angle scattering and quasiclassical approximation beyond leading order
In the present paper we examine the accuracy of the quasiclassical approach
on the example of small-angle electron elastic scattering. Using the
quasiclassical approach, we derive the differential cross section and the
Sherman function for arbitrary localized potential at high energy. These
results are exact in the atomic charge number and correspond to the leading and
the next-to-leading high-energy small-angle asymptotics for the scattering
amplitude. Using the small-angle expansion of the exact amplitude of electron
elastic scattering in the Coulomb field, we derive the cross section and the
Sherman function with a relative accuracy and ,
respectively ( is the scattering angle). We show that the correction of
relative order to the cross section, as well as that of relative
order to the Sherman function, originates not only from the
contribution of large angular momenta , but also from that of . This means that, in general, it is not possible to go beyond the accuracy
of the next-to-leading quasiclassical approximation without taking into account
the non-quasiclassical terms.Comment: 12 pages, 3 figure
Atomic screening and pair photoproduction at low energies
The effect of screening by atomic electrons on the behavior of electron and
positron wave functions in the continuous spectrum at small distances is
studied. It is shown that these asymptotics are affected not only by the static
potential of atomic electrons, but also by the polarization potential, as well
as by the exchange interaction, which is essential for nonrelativistic
electrons. A simple analytical expression is obtained for the photoproduction
cross section of pair in an atomic field near the threshold. The
spectrum and angular distribution of the produced particles are considered. It
is shown that screening significantly affects the cross section in the
near-threshold region.Comment: 8 pages, 10 figure
High-energy bremsstrahlung on atoms in a laser field
The impact of a laser field on the process of photon radiation by an ultra-relativistic electron in an atomic field is investigated. The angular distribution and the spectrum of the radiated photon are derived. By means of the quasiclassical approximation, the obtained results are exact in the parameters of the laser field and the atomic field. It is shown that the impact of the laser field is significant even for fairly average values of the laser field parameters routinely achievable nowadays. Therefore, an experimental observation of the influence of the laser field on bremsstrahlung in the atomic field is a very feasible task