共查询到20条相似文献,搜索用时 875 毫秒
1.
The resonant photoproduction of an electron-positron pair on a nucleus in the field of a pulsed light wave is studied theoretically.
The approximation where the electromagnetic pulse duration is much longer than the characteristic time of wave oscillations
is considered. The interaction of the electron and positron with the Coulomb potential of the nucleus is considered in the
Born approximation. An analytical expression for the resonant differential cross section is derived for the range of moderately
strong external fields. This cross section contains a resonant peak whose height and width are determined by the external
pulsed wave characteristics. The resonant cross section for pair photoproduction on a nucleus in a pulsed laser field can
exceed the corresponding cross section for pair photoproduction on a nucleus in the absence of an external field by an order
of magnitude. 相似文献
2.
This review contains theoretical study of nonresonant quantum electrodynamics processes of the first and second orders in the fine-structure constant in a pulsed laser field. The approximation is examined when the pulse width is considerably greater than the characteristic time of wave oscillations. It was demonstrated that for nonrelativistic particle energy the differential cross section of a process in a pulsed light fields may considerably difference from the corresponding cross section in an absence of a laser field. Results obtained may be experimentally verified by the scientific facilities at the SLAC National Accelerator Laboratory and FAIR (Facility for Antiproton and Ion Research, Darmstadt, Germany) project. 相似文献
3.
A. A. Lebed’ S. P. Roshchupkin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(1):113-122
This paper presents theoretical study of nonresonant spontaneous bremsstrahlung by an electron scattered by a nucleus in the
field of the pulsed light wave. The electron interaction with a Coulomb potential of a nucleus is considered in the first
order of perturbation theory (the Born approximation), and the interaction with an external pulsed field is taken into account
accurately. The approximation is examined when pulsewidth is considerably greater than the characteristic time of wave oscillations.
The obtained differential cross-section of the process has form of a sum over partial differential cross-sections. Each of
them corresponds to processes with emission (absorption) of certain number of wave photons. It is shown, that for spontaneous
bremsstrahlung by an electron scattered by a nucleus in the field of a pulsed light wave the distribution of a stimulated
emission-absorption probability is determined by the average value of corresponding probabilities in the case monochromatic
wave. 相似文献
4.
This review contains theoretical study of resonant quantum electrodynamics processes in a pulsed laser field. The approximation is examined when the pulse width is considerably greater than the characteristic time of wave oscillations. The lepton??s interaction with the Coulomb potential of a nucleus and each other is considered in the Born approximation. It is demonstrated that the resonant differential cross section of a process in a pulsed light fields may considerably exceed the corresponding cross section in an absence of a laser field. Results obtained may be experimentally verified by the scientific facilities at the SLAC National Accelerator Laboratory and FAIR (Facility for Antiproton and Ion Research, Darmstadt, Germany) project. 相似文献
5.
E. Haug 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(3):297-303
Using the partial-wave formalism the cross section of bremsstrahlung for
a pure Coulomb field is calculated for various atomic numbers of the
target nucleus and various incident electron energies. The results are
compared to those of previous theories. For intermediate and large atomic
numbers the latter cross sections undervalue significantly the present ones.
Except for low atomic numbers the cross sections in Born approximation with
the Coulomb correction by Elwert yield more accurate results than the cross
sections obtained by using the approximate Sommerfeld-Maue wave function.
The effect of screening is small for low atomic numbers. At nonrelativistic
energies the number of required partial waves is rather large for target
nuclei with high atomic numbers, contrary to the expectations. The pertinent
results exceed the numerical values including screening by factors of up to
five. They verify the assumption that the nonrelativistic cross section of
Sommerfeld is fairly accurate even for high atomic numbers. 相似文献
6.
Vitaly N. Nedoreshta Sergei P. Roshchupkin Alexey I. Voroshilo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2013,67(3):1-11
The theory of nonresonant scattering of a photon by an electron in the field of an intense pulsed light wave is developed. The approximation when a pulse width is considerably greater than the characteristic time of wave oscillation is considered. The nonresonant kinematic region is determined. The general relativistic expression for the nonresonant cross-section is derived for the range of the external field intensities if η 0 ? 1, η0 2 ? 1 (see Eq. (12)) is valid. The obtained differential cross-section of the process has form of a sum over partial differential cross-sections. Each of them corresponds to the process with emission (absorption) of a certain number of wave photons. It is shown, that for nonrelativistic energy the cross-section summed over all possible partial processes differs considerably from the cross-section of Compton scattering if the external field is absent and may exceed the latter over than 200%. 相似文献
7.
A. I. Smirnov 《Russian Physics Journal》1979,22(4):425-428
The density of the bremsstrahlung differential cross section of a vector particle in the Coulomb field of an atomic nucleus is calculated in the Born approximation of perturbation theory. The spectral distribution of photons in nonrelativistic and highly relativistic particle-energy regions is obtained by integration.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 98–101, April, 1979. 相似文献
8.
The low-energy electron scattering cross section in a strong Coulomb field is analyzed theoretically. It is shown that the exact cross section in a wide energy range significantly differs from the results obtained in the first Born approximation and in the nonrelativistic approximation. 相似文献
9.
H. Meier Z. Halabuka K. Hencken D. Trautmann G. Baur 《The European Physical Journal C - Particles and Fields》1998,5(2):287-291
Antihydrogen has recently been produced in collisions of antiprotons with ions. While passing through the Coulomb field of
a nucleus an antiproton will create an electron-positron pair. In rare cases the positron is bound by the antiproton and an
antihydrogen atom produced. We calculate the production of relativistic antihydrogen atoms by bound-free pair production.
The cross section is calculated in the semiclassical approximation (SCA), or equivalently in the plane wave Born approximation
(PWBA) using exact Dirac-Coulomb wave functions. We compare our calculations to the equivalent photon approximation (EPA).
Received: 19 December 1997 / Published online: 10 March 1998 相似文献
10.
In the frame of the Born approximation it was theoretically investigated nonresonant muon pair production in e
+
e
− collision in the field of elliptically polarized electromagnetic wave in the general relativistic case. It was analyzed in
detail the reaction kinematics. It was derived the expressions for the amplitude and the cross section of the nonresonant
muon pair production in e
+
e
− annihilation in the moderately strong field. It was demonstrated that the partial cross-section is factorized as a product
of the cross section of the muon pair production from e
+
e
− pair in the absence of the external field and the probability of emission and absorption of photons from the wave.
Original Text ? Astro, Ltd., 2009.
The article is published in the original. 相似文献
11.
A process of pair production by a circularly polarized photon in the field of an unpolarized atomic electron was considered in the Weizaecker-Williams approximation. The degree of longitudinal polarization of a positron and an electron was calculated. An exclusive cross section, as well as a spectral distribution, were obtained. We estimate the accuracy of our calculations at the level of a few percent. We show the identity of the positron polarization for the considered process and for the process of pair production in the screened Coulomb field of a nucleus. 相似文献
12.
A simple method for calculating the amplitude and the cross section for the Coulomb breakup of a light nucleus into two fragments in the field of a heavy ion at relativistic collision energies is proposed on the basis of time-dependent perturbation theory. It is shown that the resulting amplitude for the process in question has a correct nonrelativistic limit. The contribution of the longitudinal component of the Coulomb field of a heavy ion tends to zero in the ultrarelativistic limit. A specific implementation of the method is demonstrated by taking the example of the Coulomb breakup reaction 208Pb(8B, 7Bep)208Pb at various collision energies. The results are found to be in agreement with experimental data. 相似文献
13.
E. Borie 《Zeitschrift für Physik A Hadrons and Nuclei》1981,302(3):219-222
The analytic expression for the differential pair production cross section, obtained using full Furry-Sommerfeld-Maue wave functions for the electron and positron, is integrated numerically over angles without further approximation. The resulting Coulomb corrections to the total pair production cross section are compared with existing interpolations in the energy range 10 MeV to 50 MeV, and their experimental relevance is discussed. 相似文献
14.
O. I. Denisenko 《Laser Physics》2008,18(7):920-924
The electron-positron pair production in a two-photon collision in the field of a moderately strong circularly polarized laser wave was theoretically investigated. The nonresonant kinematics of the pair production has been studied and the cross section for the Breit-Wheeler process was obtained. 相似文献
15.
A. I. Smirnov 《Russian Physics Journal》1978,21(10):1325-1329
A general expression is calculated for the differential cross section of the formation of an electron-positron pair and a photon by a photon in the Coulomb field of an atomic nucleus. Particular kinematic cases of the process which have not previously been investigated are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 91–96, October, 1978. 相似文献
16.
The equivalent photon approximation is used to calculate the nuclear pair production cross section in the field of an electromagnetic wave of arbitrary intensity. The cases of low and high wave intensities are considered, as is the limiting approach to a constant field.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 15–20, May, 1977. 相似文献
17.
A study is made of the influence of the Coulomb field of a nucleus on a process that also occurs in the absence of interaction with the nucleus. It is shown that the approximation of equivalent photons applies to the interference between the diagram without interaction with the nucleus and the diagram of two-photon exchange with the nucleus, which contributes to the cross section of the process to the same order in the fine structure constant as the square of the diagram of single-photon exchange. As an example, the method of equivalent photons is used to calculate the cross section of the decay π → μ +ν on a nucleus. 相似文献
18.
The process of resonant scattering of a lepton by a lepton in the field of pulsed light wave in general relativistic case
is studied theoretically. The approximation when a pulsewidth is considerably greater than the characteristic time of wave
oscillation is considered. The analytical expression for the resonant differential cross-section of concerned process is derived
within the framework of the first order of the perturbation theory with respect to external laser field; it contains the resonant
peak, the altitude and the width of which are defined by the external pulsed wave characteristics. It is demonstrated, that
the resonant differential cross-section of scattering of an electron by an electron (an electron by a positron, an electron
by a muon) in the pulsed light field may be several orders of magnitude greater than the corresponding one in the external
field absence. The derived results may be verified experimentally for example by scientific facility at SLAC National Accelerator
Laboratory. 相似文献
19.
M. M. Mirabutalybov 《Russian Physics Journal》2010,53(3):276-295
In the context of nonrelativistic theory in the distorted wave approximation, a three-dimensional form of analytical expression
for the differential cross section of scattering of nucleons with intermediate energies on atomic nuclei is derived. In the
context of this theory, the main parameters of elastic scattering of protons with incident energy of 1 GeV on the 208Pb nucleus are determined. For inelastic scattering of protons with nuclear surface vibrations, giant multipole resonances
in the excited nucleus are investigated for the collective nucleus model. The energy losses of the scattered proton are calculated
together with the energies of giant dipole and quadrupole resonances and nuclear surface vibration energy. This allows the
deformation parameter of the excited nucleus to be calculated. 相似文献
20.
S. P. Roshchupkin 《Physics of Atomic Nuclei》2001,64(2):243-252
In the general relativistic case, the nonresonance photoproduction of electron-positron pairs on a nucleus in the field of two circularly polarized light waves propagating in one direction is theoretically investigated. It is shown that there are two essentially different kinematical regions: the noninterference region, where the Bunkin-Fedorov quantum parameters play the role of multiphoton parameters, and the interference region, where interference effects are important and where quantum interference parameters are treated as multiphoton parameters. The interference effect is found in the photoproduction of an electron-positron pair on a nucleus in the field of two light waves. This effect occurs in the interference region and is due to the production of an electron-positron pair in the plane spanned by the light wave vector and the incident-photon momentum and to stimulated correlated emission and absorption of photons of the two waves. The cross sections for pair photoproduction on a nucleus in the above kinematical regions are determined for moderately strong fields. It is shown that, in the interference region, the partial cross sections for the case where there is a correlated emission (absorption) of the same number of photons of the two waves can significantly exceed the corresponding cross sections in any other geometry. 相似文献