arXiv subjects

B. Manaut

Publications and source records attributed to B. Manaut.

50 records · Page 3Linked to original sources

arXiv2012

Muon's anomalous magnetic moment effects on laser assisted Coulomb scattering process

Laser assisted Coulomb scattering by relativistic electron and heavy electron (muon) is studied by using Salamin waves (Salamin 1993) in the Weak Field Approximation (WFA). Both electron and muon are described by the Dirac equation, with the anomalous magnetic moment effects fully included. The generalization of this paper to heavy electron (muon) gives interesting insights as to how the mass affects the magnitude of the differential cross sections. No significant difference in the muon's DCS with and without AMM effects was detected.

physics.atom-ph↗

arXiv2012

Spin effects in laser-assisted semirelativistic excitation of atomic hydrogen by electronic impact

New insights into our understanding of the semirelativistic excitation of atomic hydrogen by electronic impact have been made possible by combining the use of polarized electron beams and intense laser field. The paper reviews relativistic theoretical treatment in laser-assisted electron scattering with particular emphasis upon spin effects. Different spin configurations for inelastic electron-atom collisions is also discussed. The role of laser field in such collision is of major importance and reveals new information on the dynamics of the collision process. The examined modern theoretical investigations of such relativistic laser-assisted collisions have shown that the need for experimental data is of a paramount importance in order to asses the accuracy of our calculations.

physics.atom-ph↗

arXiv2012

Semirelativistic $1s-2s$ excitation of atomic hydrogen by electron impact

In the framework of the first Born approximation, we present a semirelativistic theoretical study of the inelastic excitation ($1s_{1/2}\longrightarrow 2s_{1/2}$) of hydrogen atom by electronic impact. The incident and scattered electrons are described by a free Dirac spinor and the hydrogen atom target is described by the Darwin wave function. Relativistic and spin effects are examined in the relativistic regime. A detailed study has been devoted to the nonrelativistic regime as well as the moderate relativistic regime. Some aspects of this dependence as well as the dynamic behavior of the DCS in the relativistic regime have been addressed.

physics.atom-ph↗

arXiv2012

Laser-Assisted Semi Relativistic Excitation of Atomic Hydrogen by Electronic Impact

The excitation of H ($1s-2s$) by electron impact in the presence and in the absence of the laser field is studied in the framework of the first Born approximation. The angular variation of the laser-assisted differential cross section (DCS) for atomic hydrogen by electronic impact is presented at various kinetic energies for the incident electron. The use of Darwin wave function as a semirelativistic state to represent the atomic hydrogen gives interesting results when the condition $z/c\ll1$ is fulfilled. A comparison with the non relativistic theory and experimental data gives good agreement. It was observed that beyond (2700 $eV$) which represents the limit between the two approaches, the non relativistic theory does not yield close agreement with our theory and that, over certain ranges of energy, it can be in error by several orders of magnitude. The sum rule given by Bunkin and Fedorov and by Kroll and Watson \cite{22} has been verified in both nonrelativistic and relativistic regimes.

physics.atom-ph↗

arXiv2012

Electron's anomalous magnetic moment effects on laser assisted ionization of atomic hydrogen by electronic impact

Electron-impact ionization of atomic hydrogen with the electron's anomalous mag- netic moment (AMM) effects are examined. The formulas for the laser-assisted relativis- tic triple differential cross section (TDCS) in the coplanar binary geometry developed earlier by Y. Attaourti and S. Taj [Phys. Rev. A 69, 063411 (2004)] are used to check the consistency of our computations when the anomaly $κ$ is taken to be zero. We show that the contribution of the terms containing the AMM effects even in the first Born approximation has an important contribution, so it must be included in any reliable analysis. A full analytical calculation for the TDCS is presented.

physics.atom-ph↗

arXiv2010

Electron's anomalous magnetic moment effects on electron-hydrogen elastic collisions in the presence of a circularly polarized laser field

The effect of the electron's anomalous magnetic moment on the relativistic electronic dressing for the process of electron-hydrogen atom elastic collisions is investigated. We consider a laser field with circular polarization and various electric field strengths. The Dirac-Volkov states taking into account this anomaly are used to describe the process in the first order of perturbation theory. The correlation between the terms coming from this anomaly and the electric field strength gives rise to new results, namely the strong dependence of the spinor part of the differential cross section (DCS) with respect to these terms. A detailed study has been devoted to the non relativistic regime as well as the moderate relativistic regime. Some aspects of this dependence as well as the dynamical behavior of the DCS in the relativistic regime have been addressed.

physics.atom-ph↗

arXiv2009

Mott scattering in strong laser field revisited

In this work, we review and correct the first Born differential cross section for the process of Mott scattering of a Dirac-Volkov electron, namely, the expression (26) derived by Szymanowski et al [Physical Review A {\bf 56}, 3846 (1997)]. In particular, we disagree with the expression of $(\frac{dσ}{dΩ})$ they obtained and we give the exact coefficients multiplying the various Bessel functions appearing in the scattering differential cross section. Comparison of our numerical calculations with those of Szymanowski et al. shows qualitative and quantitative differences when the incoming total electron energy and the electric field strength are increased particularly in the direction of the laser propagation. Such corrections are very important since the relativistic electronic dressing of any Dirac-Volkov charged particle gives rise to these coefficients that multiply the various Bessel functions and the relativistic study of other processes (such as excitation, ionisation, etc....) depends strongly of the correctness and reliability of the calculations for this process of Mott Scattering in presence of a laser field. Our work has been accepted [Y. Attaourti, B. Manaut, Physical Review A {\bf 68}, 067401 (2003)] but only as a comment. In this paper, we give the full details of the calculations as well as the clear explanation of the large discrepancies that their results could cause when working in the ultra relativistic regime and using a very strong laser field corresponding to an electric field $\varepsilon=5.89$ in atomic units.

physics.atom-ph↗

arXiv2008

Mott Scattering of polarized electrons in a circularly polarized laser field

We present a study of Mott scattering of polarized electrons in the presence of a laser field with circular polarization using the helicity formalism and the introduction of the well known concept of non flip differential cross section as well as that of flip differential cross section. The results we have obtained in the presence of a laser field are coherent with those obtained in the absence of a laser field. We have studied the relativistic regime as well as the non relativistic regime that are precisely defined in the text. Two important consistency checks have been carried out successfully. The first one is that the sum of both differential cross sections (one with spin up, the other with spin down) always gives the unpolarized differential cross section. The second one is that the relativistic unpolarized differential cross section converges to the non relativistic differential cross section in the limit of small velocities. Moreover, the results obtained using the sofware Reduce \cite{8} gave rise to non contracted coefficients that have been dealt with using the geometry chosen.

physics.atom-ph↗

arXiv2005

Instantaneous versus non-instantaneous approach to relativistic ionization of atomic hydrogen by electron impact

We present a theoretical model for atomic hydrogen ionization by electron impact in the instantaneous approximation and the more accurate non-instantaneous approach using the methods of Quantum Electrodynamics, for the binary coplanar and the coplanar asymmetric geometries. All electrons are described by plane wave functions in the coplanar binary geometry but in the asymmetric geometry the ejected electron is described by a Sommerfeld-Maue wave function. It is shown that the two models give the same results in the non relativistic limit for the binary coplanar geometry where the interactions can be treated as instantaneous. However, this is no longer true for the relativistic case where one has to take into account both the instantaneous interaction and the radiation interaction. These results are obtained in the first order of perturbation theory.

physics.atom-ph↗

arXiv2004

Exact semi-relativistic model for ionization of atomic hydrogen by electron impact

We present a semi-relativistic model for the description of the ionization process of atomic hydrogen by electron impact in the first Born approximation by using the Darwin wave function to describe the bound state of atomic hydrogen and the Sommerfeld-Maue wave function to describe the ejected electron. This model, accurate to first order in $Z/c$ in the relativistic correction, shows that, even at low kinetic energies of the incident electron, spin effects are small but not negligible. These effects become noticeable with increasing incident electron energies. All analytical calculations are exact and our semi-relativistic results are compared with the results obtained in the non relativistic Coulomb Born Approximation both for the coplanar asymmetric and the binary coplanar geometries.

physics.atom-ph↗

arXiv2004

Mott scattering of polarized electrons in a strong laser field

We present analytical and numerical results of the relativistic calculation of the transition matrix element $S_{fi}$ and differential cross section for Mott scattering of initially polarized Dirac particles (electrons) in the presence of strong laser field with linear polarization. We use exact Dirac-Volkov wave functions to describe the dressed electrons and the collision process is treated in the first Born approximation. The influence of the laser field on the degree of polarization of the scattered electron is reported.

physics.atom-ph↗

arXiv2004

A note on the polarization of the laser field in Mott Scattering

In the first Born approximation and using an elliptically polarized laser field, the Mott scattering of an electron by a Coulomb potential is investigated using the Dirac-Volkov states to describe the incident and scattered electrons. The results obtained are compared with the results of S.M. Li \textit{et al} \cite{1} for the case of a linearly polarized laser field and with the results of Y. Attaourti \textit{et al} \cite{2} for the case of a circular polarization.

physics.atom-ph↗

arXiv2002

Comment on Mott Scattering in strong Laser Field

The first differential cross section for Mott scattering of a Dirac-Volkov electron is reviewed. The expression (26) derived by Szymanowski et al. [Physical Review A {\bf 56}, 3846,(1997)] is corrected. In particular, we disagree with the expression of $(\frac{dσ}{dΩ})$ they obtained and we give the exact coefficients multiplying the various Bessel functions appearing in the scattering differential cross section.

hep-ph↗

arXiv2002

Relativistic electronic dressing

We study the effects of the relativistic electronic dressing in laser-assisted electron-hydrogen atom elastic collisions. We begin by considering the case when no radiation is present. This is necessary in order to check the consistency of our calculations and we then carry out the calculations using the relativistic Dirac-Volkov states. It turns out that a simple formal analogy links the analytical expressions of the differential cross section without laser and the differential cross section in presence of a laser field.

physics.atom-ph↗