共查询到20条相似文献,搜索用时 15 毫秒
1.
V. N. Nedoreshta A. I. Voroshilo S. P. Roshchupkin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):451-458
In the frame of the Born approximation we theoretically
investigate resonant scattering of an electron by a muon in the
field of elliptically polarized electromagnetic wave in the
general relativistic case. It is studied kinematics of a
scattering of an electron in resonant region. It is derived the
expressions for the amplitude and the cross-section of the
resonant scattering of an electron by a muon when the invariant
intensity parameter of the laser field is small (ηe ≪1).
It is demonstrated that the resonant cross-section of a scattering
may be several orders of magnitude higher than the cross-section
of a scattering in the absence of the external field. 相似文献
2.
A. I. Voroshilo S. P. Roshchupkin O. I. Denisenko 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):433-440
We present, for general relativistic case, a
theoretical study of resonance of exchange amplitude when a photon
is scattered by an electron in the field of a circularly polarized
wave. Resonances are related to a virtual intermediate particle
that falls within the mass shell. We find conditions when
resonances occur in exchange amplitude. We derive the expressions
for the resonant amplitudes and the differential cross-sections
when the invariant intensity parameter of the laser field is small
(η≪1) and the interference of direct and exchange
amplitudes is absent. It is demonstrated that the resonant
cross-section of scattering may be several orders of magnitude
higher than the cross-section of Compton effect in the absence of
the external field. 相似文献
3.
We calculate the one-photon loop radiative corrections to virtual pion Compton scattering
→
, that subprocess which determines in the one-photon exchange approximation the pion-nucleus bremsstrahlung reaction
Z →
Z
. Ultraviolet and infrared divergencies of the loop integrals are both treated by dimensional regularization. Analytical
expressions for the O() corrections to the virtual Compton scattering amplitudes, A(s, u, Q) and B(s, u, Q) , are derived with their full dependence on the (small) photon virtuality Q from 9 classes of contributing one-loop diagrams. Infrared finiteness of these virtual radiative corrections is achieved
(in the standard way) by including soft photon radiation below an energy cut-off . In the region of low
center-of-mass energies, where the pion-nucleus bremsstrahlung process is used to extract the pion electric and magnetic
polarizabilities, we find radiative corrections up to about -3% for = 5 MeV. Furthermore, we extend our calculation of the radiative corrections to virtual pion Compton scattering
→
by including the leading pion-structure effect in the form of the polarizability difference - . Our analytical results are particularly relevant for analyzing the data of the COMPASS experiment at CERN which aims at
measuring the pion electric and magnetic polarizabilities with high statistics using the Primakoff effect. 相似文献
4.
Alexander J. Silenko 《The European Physical Journal C - Particles and Fields》2008,57(3):595-599
The exact solution of the Corben–Schwinger equations is obtained for spin-1 particles without an anomalous magnetic moment
in a uniform magnetic field. The exact Hamiltonian in the Foldy–Wouthuysen representation is derived. The conservation of
projections of the polarization operator onto four directions is proved. The approximate conservation of projections of this
operator onto the horizontal axes of the cylindrical coordinate system is established. For spin-1 particles with the anomalous
magnetic moment, the Hamiltonian in the Foldy–Wouthuysen representation is deduced within first order terms in the Planck
constant. Dynamics of spin-1 particles with the anomalous magnetic moment and their spins in the strong uniform magnetic field
are calculated. 相似文献
5.
6.
Relativistic Mean Field (RMF) theory is used to investigate the behavior of the spin orbit potential,V
ls, in nuclear states of very large deformation and high angular velocity. As a by-product we present a set of parameters for an approximation of the relativistic scalar- and vector-potentialsS andV in the Dirac equation in terms of Saxon-Woods shapes. These reproduce more or less the same single particle specta as a full selfconsistent relativistic mean field calculation.Dedicated to Prof. Dr. H.J. Mang on the occasion of his 60th birthday 相似文献
7.
S. P. Purohit K. C. Mathur 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):173-177
In this paper we report a study on the elastic scattering of electrons by lithium and sodium atoms in the presence of circularly
polarized resonant laser field within the framework of the two-state rotating wave approximation. The effect of laser on projectile
electrons is described by Volkov states. The frequency of the laser field is chosen to match with the 2s–3p (3s–3p) transition
frequency in lithium (sodium) atoms. The total and differential elastic cross sections with single photon exchange are calculated
for intermediate energies (50–150 eV) and laser intensity (107–1011 W cm-2).
An erratum to this article can be found online at http://dx.doi.org/.
An erratum to this article can be found at 相似文献
8.
N. T. Khai T. D. Thiep T. T. An P. V. Cuong N. T. Vinh A. G. Belov O. D. Maslov 《Physics of Particles and Nuclei Letters》2008,5(5):437-440
Bremsstrahlung emission, or radiation loss, is the dominant mechanism of energy dissipation of electrons at relativistic energies
greater than a few MeV when it is subjected to acceleration in the field of the nucleus or of the electrons. In this study,
the Monte Carlo calculations for bremsstrahlung spectra have been described for the case of a thick tungsten target with incident
electron beams from 10 to 50 MeV, where secondary interactions induced by the electrons and photons in the target, such as
energy loss, absorption, scattering, and (e
+, e
−)-pair production effects, were taken into account.
The text was submitted by the authors in English. 相似文献
9.
A. Yu. Elizarov I. I. Tupitsyn 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):67-74
The plane wave Born approximation is used to calculate total
electron impact ionization cross section of silver and copper.
Wavefunctions of the target and residual ions were modeled by non orthogonal
Hartree-Fock and Dirac-Fock orbitals. The wave
functions of the atom and residual ion
are calculated with allowance for relaxation effects.
The one-electron wavefunction of the continuous spectrum for the ejected
electron is obtained using single-configuration Hartree-Fock and
Dirac-Fock method. The orthogonalization of the ejected electron wave
functions to all occupied orbitals of the target atom is performed.
Results of calculations are compared to available experimental measurements
and theoretical calculations performed by non relativistic one-electron
PWBA, where the ejected electrons is modeled by the hydrogenic Coulomb
wave function. 相似文献
10.
A refined interpretation of Christiansen filter experiments is described, which allows for the effects of inhomogeneities in the powder column of the filter. Using this procedure the evaluation of experiments on enriched samples of lead isotopes provided the neutron coherent scattering lengths (in fm) for the separated isotopes:b (204) =10.6 ± 2.0;b (206)=9.23 ± 0.05;b (207)=9.28 ± 0.04 andb (208)=9.50 ± 0.06. The corresponding potential scattering radius R was obtained by taking account of resonance contributions as earlier used in the determination of the neutron's electric polarizability. The found R=9.74 ± 0.07 fm is in good argreement with the literature. This confirms the correctness of the used resonance contributions.Work partially supported by the Bundesministerium für Forschung und Technologie 相似文献
11.
D. Ebert R. N. Faustov V. O. Galkin 《The European Physical Journal C - Particles and Fields》2009,60(2):273-278
Masses of the ground-state light tetraquarks are dynamically calculated in the framework of the relativistic diquark–antidiquark
picture. The internal structure of the diquark is taken into account by calculating the form factor of the diquark–gluon interaction
in terms of the overlap integral of the diquark wave functions. It is found that scalar mesons with masses below 1 GeV, f
0(600) (σ), K
0*(800) (κ), f
0(980) and a
0(980), agree well with the light-tetraquark interpretation. 相似文献
12.
E. Hanelt A. Grewe K. -H. Schmidt T. Brohm H. -G. Clerc M. Dornik M. Fauerbach H. Geissel A. Magel G. Münzenberg F. Nickel M. Pfützner C. Scheidenberger M. Steiner K. Sümmerer B. Voss M. Weber J. Weckenmann C. Ziegler 《Zeitschrift für Physik A Hadrons and Nuclei》1993,346(1):43-46
The longitudinal-momentum distributions of projectile fragments from 0.8 A GeV136Xe and 1 A GeV197Au projectiles impinging on targets of beryllium and aluminium, respectively, have been measured using the projectile-fragment separator FRS at GSI. Different momentum distributions have been found for two different classes of fragmentation processes: the abundant hot fragmentation with several nucleons evaporated from the prefragments, and the rare cold fragmentation with only protons removed from the projectile, but no nucleons evaporated. The data are compared to model calculations.This article comprises part of the Ph.D. thesis of B. Voss 相似文献
13.
In the formation of a compound nucleus the evolution of a dinuclear system is considered. The enhanced yield of light particles for some reactions is explained by the dynamic reasons. The role of quantum and thermal fluctuations is discussed. The results of the previous paper are confirmed.Authors wish to thank Prof. V.V. Volkov for his active attention and comments. 相似文献
14.
A. E. Zarvin N. G. Korobeishchikov V. V. Kalyada V. Zh. Madirbaev 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):101-110
An experimental study of the formation of mixed van der Waals oxygen-isoprene complexes, generated in an expanding supersonic
helium-oxygen-isoprene jet at various stagnation pressures and at diverse oxygen and isoprene concentrations, has been performed.
To measure the composition and distribution of the partial densities of the individual components, molecular beam mass spectrometry
was adapted to pulsed modes of gas source operation. The particularities of applying mass spectrometry to studying clustered
isoprene streams in a pulsed mode have been discussed. The composition of small clusters generated in a free supersonic jet
has been checked for dependencies upon the initial mixture composition and stagnation pressure. The mechanism of nucleation
has been identified for different partial concentrations of impurities in the helium stream. It has been shown that, even
at a 0.3% concentration of isoprene in the mixture, nucleation starts with the formation of hydrocarbon complexes. The specific
features of the dissociative ionization of van der Waals complexes, consisting of pure isoprene and mixed complexes, have
been discussed. The conditions needed for the formation of binary oxygen-isoprene van der Waals complexes have been identified. 相似文献
15.
C. Guo L. Luan X. Ding F. Zhang F. G. Shi F. Gao L. Liang 《Applied physics. B, Lasers and optics》2009,95(4):779-785
Eu2+ and Mn2+ co-activated Sr5(PO4)3Cl phosphors with blue and orange color double emission bands, under a broad-band excitation wavelength range of 340–400 nm,
were synthesized by the solid-state reaction. It was found that the processing parameters, including the fluxes, annealing
time and activators concentrations, affect the emission intensity and other luminescent properties. Energy transfer between
Eu2+ and Mn2+ was discovered and the transfer efficiency was also estimated based on relative intensities of Eu2+ and Mn2+ emission. Thus the relative strength of blue and orange emission intensities could be tuned by varying the relative concentration
of Eu2+ and Mn2+. Since the photoluminescence excitation spectra of the newly developed Sr5(PO4)3Cl:Eu2+, Mn2+ phosphors exhibit a strong absorption in the range of 340–400 nm, they are promising for producing UV-LED-based white LEDs. 相似文献
16.
G. Grégoire B. Lucas M. Barat J. A. Fayeton C. Dedonder-Lardeux C. Jouvet 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(1):109-116
UV photoinduced fragmentation of protonated aromatic amino acids has emerged the last few years, coming from a situation where
nothing was known to what we think a good understanding of the optical properties. We will mainly focus this review on the
tryptophan case. Three groups have mostly done spectroscopic studies and one has mainly been involved in dynamics studies
of the excited states in the femtosecond/picosecond range and also in the fragmentation kinetics from nanosecond to millisecond.
All these data, along with high level ab initio calculations, have shed light on the role of the different electronic states
of the protonated molecules upon the fragmentation mechanisms. 相似文献
17.
S. Engstler G. Raimann C. Angulo U. Greife C. Rolfs U. Schröder E. Somorjai B. Kirch K. Langanke 《Zeitschrift für Physik A Hadrons and Nuclei》1992,342(4):471-482
The fusion reactions6Li(p, )3He,6Li(d, )4He, and7Li(p, )4He have been studied over the c.m. energy rangeE=10 to 1450 keV. Each reaction involved the use of hydrogen projectiles and LiF solid targets as well as Li projectiles and hydrogen molecular gas targets. In all cases the effects of electron screening on the low-energy fusion cross sections (exponential enhancement) have been observed; the effects are somewhat stronger in the case of atomicp ord projectiles compared to the case of molecularH
2
orD
2
gas targets. If isotopic effects on electron screening are negligible, all three reactions should exhibit the same enhancements for each set of experimental techniques. The measurements confirmed this expectation to a large extent.Supported in part by the Landesamt Nordrhein-Westfalen (IVA5-10600387), the Deutsche Forschungsgemeinschaft (Ro429/ 18-2 and Ro429/21-1), and the Comision Interministerial de Ciencia y Tecnologia (AEN90-0932) 相似文献
18.
J. Z. Hu Z. W. Yu X. B. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):381-385
We analyze the problem of approximate quantum cloning when the
quantum state is between two latitudes on the Bloch’s sphere. We
present an analytical formula for the optimized 1-to-2 cloning. The
formula unifies the universal quantum cloning (UQCM) and the phase covariant quantum cloning. 相似文献
19.
S. A. Bass C. Hartnack H. Stöcker W. Greiner 《Zeitschrift für Physik A Hadrons and Nuclei》1995,352(2):171-174
We present a microscopic calculation of neutronsqueeze-out in relativistic heavy ion collisions at beam energies betweeen 400 and 1000 MeV/nucleon. After demonstrating the importance of the correct isospin treatment for the neutron to proton ratio, our main emphasis is put on the investigation of the properties of neutronsqueeze-out. Thesqueeze-out ratio increases monotonously with the transverse momentum of the neutrons. This ratio is independent of the incident beam energy if plotted versusp
t
/p
proj
. Most importantly, we observe a strong dependence on the nuclear equation of state and momentum dependent interaction.Supported by GSI, BMFT and DFG 相似文献
20.
V. V. Bezotvetnykh A. V. Burenin Yu. N. Morgunov Yu. A. Polovinka 《Acoustical Physics》2009,55(3):376-382
Results of an experimental study of low-frequency broadband pulsed signal propagation in a waveguide that includes the shelf zone, the continental slope, and the deep sea region are presented. Using phase-manipulated signals with central frequencies of 366 and 600 Hz, pulsed characteristics are measured at six points along the propagation track, the maximal distance from the source being 368 km. It is experimentally demonstrated that, in the presence of a negative sound velocity gradient in the near bottom layer on the shelf with a small bottom slope, the choice of the source position at the shelf bottom near the shoreline provides the formation of a continuous illumination zone in the deep sea near the USC axis and a stable pulsed characteristic with two main sound energy arrivals. The propagation velocity of the pulse that is last to arrive is identical (within the measurement error) to the velocity of sound on the USC axis at the point of reception. Possibilities for practical application of the results obtained from the experiment are discussed. 相似文献