Angular distribution of ejected electrons at the laser-cluster interactions

The histograms of deflection angles of electrons ejected from Xe clusters irradiated by femtosecond super-intense laser pulses are presented. The dependence of the angular distribution on the peak laser intensity, the pulse duration, and the cluster position is considered. A clear relationship between the final electron energy and the deflection angle is shown. The deflection angles are calculated by solving the relativistic equation of motion taking into account the Lorentz force and the Coulomb field of the ionized cluster. The ions in the cluster undergo sequential multiple ionization up to charge multiplicity Z = 26. The measurements of the electron angular distributions allow us to reproduce the imaging dynamics of outer ionization of the cluster at the leading edge of the relativistic femtosecond laser pulse.     

Rescattering of ultralow-energy electrons for single ionization of Ne in the tunneling regime

Electron emission for single ionization of Ne by 25 fs, 1.0 PW/cm(2) laser pulses at 800 nm has been investigated in a kinematically complete experiment using a "reaction microscope." Mapping the complete final state momentum space with high resolution, a distinct local minimum is observed at P(e parallel )=0, where P(e parallel ) is the electron momentum parallel to the laser polarization. Whereas tunneling theory predicts a maximum at zero momentum, our findings are in good agreement with recent semiclassical predictions which were interpreted to be due to "recollision."     

Highly charged ions from laser-cluster interactions: local-field-enhanced impact ionization and frustrated electron-ion recombination

Our molecular dynamics analysis of Xe_{147-5083} clusters identifies two mechanisms that contribute to the yet unexplained observation of extremely highly charged ions in intense laser cluster experiments. First, electron impact ionization is enhanced by the local cluster electric field, increasing the highest charge states by up to 40%; a corresponding theoretical method is developed. Second, electron-ion recombination after the laser pulse is frustrated by acceleration electric fields typically used in ion detectors. This increases the highest charge states by up to 90%, as compared to the usual assumption of total recombination of all cluster-bound electrons. Both effects together augment the highest charge states by up to 120%, in reasonable agreement with experiments.     

Effects of electron-interface-phonon interactions on interactions between electrons in double-heterostructures

Effects of electron-interface-phonon interaction on the interaction between electrons in double heterostructures are considered. It is found that the interaction potential between electrons caused by each of four interface-phonon modes is different. For electrons moving at the two interfaces of double heterostructure, the interaction energies of the electrons produced by the interaction with antisymmetric modes are positive which indicate that the forces between electrons are repulsive. The interaction energies caused by interaction with symmetric modes are negative and the forces are attractive. The resultant of the forces are attractive and become larger when the width of potential barrier decreases for InAs/GaSb/InAs double heterostructure.     

Rescattering for extended atomic systems

Laser-driven rescattering of electrons is the basis of many strong-field phenomena in atoms and molecules. Here, we will show how this mechanism operates in extended atomic systems, giving rise to effective energy absorption. Rescattering from extended systems can also lead to energy loss, which in its extreme form results in nonlinear light-induced trapping. Intense-laser interaction with atomic clusters is discussed as an example. We explain fast electron emission, seen in experimental and numerically obtained spectra, by rescattering of electrons at the highly charged cluster.     

Inelastic interactions of electrons with cylindrical interfaces

A theory was developed to deal with inelastic interactions for an electron moving parallel to the axis of a cylindrical structure. Formulas for the differential inverse inelastic mean free path (DIIMFP) and the total inverse inelastic mean free path (IIMFP) were derived using dielectric response theory. A sum-rule-constrained extended Drude dielectric function with spatial dispersion was applied to calculate DIIMFPs and IIMFPs for a solid wire and a cavity in solid. The calculated results showed that surface excitations occurred as the electron moved near the boundary either inside or outside the solid, whereas volume excitations arose only for electron moving inside the solid. It was found that the probability for surface excitations increases and that for volume excitations decreases for an electron moving close to the surface. Near the surface, the decrease in volume excitations is compensated by the increase in surface excitations. For a cavity in solid, the IIMFP inside the solid can be approximated by a constant value equal to the IIMFP for the infinite solid, except in the immediate vicinity of the cavity boundary.     

Rescattering effect in above-threshold ionization processes

The Keldysh-Faisal-Reiss (KFR) theory for Above-Threshold Ionization (ATI) phenomenon is generalized to include the effect that ionized electrons return to the vicinity of the ion core and rescatter with it. The theoretical calculation of such rescattering effects for the ground state of hydrogen under linearly polarized laser light yields good agreement with recent findings in ATI experiments.     

Macroscopic relativistic dynamics of hyperlight interactions of electrons

The general solution is given for the problem of the laws of motion of an electron in the field of a hyperlight electron in a medium with arbitrary initial conditions. Effective estimates of the time of approach of the electrons are found, which is of interest for the theory of self-contraction of intense electron beams.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 73–76, April. 1982.     

Generation of surface electrons in femtosecond laser-solid interactions

The characteristics of hot electrons produced by p-polarized femtosecond laser-solid interactions are studied. The experimental results show that the outgoing electrons are mainly emitted in three directions: along the target surface, the normal direction and the laser backward direction. The electrons flowing along the target surface are due to the confinement of the electrostatic field and the surface magnetic field, while the electrons in the normal direction due to the resonant absorption.     

Rescattering production of dileptons in nucleus-nucleus collisions

We present a space-time formulation for the rescattering of hard partons produced in primary QCD subcollisions within a nucleus-nucleus collision. As an application we calculate the rescattering rate for dilepton production in 100 GeV/A+100 GeV/A uranium-uranium collisions.     

利用韧致辐射诊断激光等离子体相互作用产生的超热电子

超短脉冲强激光与等离子体相互作用时产生的向靶内传输的超热电子在“快点火”方案中起着极其重要的作用.对于这部分向靶内传输的超热电子，韧致辐射方法是一种能有效、全面获得超热电子各方面信息的诊断方法.通过三维蒙特卡罗程序MCNP模拟了超热电子在靶材料中的输运以及它们在靶后方向产生的韧致辐射的性质，论证了韧致辐射诊断方法的可行性. 关键词： 超热电子 韧致辐射 诊断 MCNP程序     

Rescattering effects in \phi photoproduction

We calculate the contribution from rescattering of pairs produced by photoproduction of to the photoproduction of mesons. The photoproduction of mesons is presently a hot topic due to the possibility that an intrinsic hidden strangeness contribution in the nucleon flavor wave function may be revealed in this process, and due to the possibility that the structure of scalar mesons could be accessible experimentally via interference in the system. We show that rescattering makes an important contribution to photoproduction which could – if neglected – mislead the interpretation of the forthcoming high precision data. Received: 14 September 2000 / Revised version: 1 February 2001 / Published online: 12 April 2001     

Production of excited electrons ine + e − interactions

We present a complete lowest order calculation of the processe ⁺ e ^?→(e ^*)→e ⁺ e ^? ρ based on a phenomenological Lagrangian where interference with “standard” amplitudes and spin correlation effects are considered. The calculation has been implemented in a Monte Carlo generator of unweighted events and can be used to study interactions with polarized beams as well as the effects of other excited fermions.     

Nonlinear resonance absorption in the laser-cluster interaction

Rare-gas or metal clusters are known to absorb laser energy very efficiently. Upon cluster expansion, the Mie plasma frequency may become equal to the laser frequency. This linear resonance has been well studied both experimentally and theoretically employing pump probe schemes. In this work, we focus on the few-cycle regime or the early stage of the cluster dynamics, where linear resonance is not met but, nevertheless, efficient absorption of laser energy persists. By retrieving time-dependent oscillator frequencies from particle-in-cell simulation results, we show that nonlinear resonance is the dominant mechanism behind outer ionization and energy absorption in near infrared laser-driven clusters.     

X-ray spectroscopic diagnostics of ultrashort laser-cluster interaction at the stage of the nonadiabatic scattering of clusters

X-ray spectroscopic diagnostics of laser-cluster interaction at the stage of nonadiabatic scattering of clusters and formation of a spatially uniform plasma channel has been performed. The experimental investigations have been carried out on a Ti:Sa laser setup with a pulse duration of about 65 fs and an energy up to 600 mJ. It has been shown that, within 10 ps from the beginning of a laser femtosecond pulse, the laser-cluster interaction forms a uniform plasma channel with a length of 0.4 to 1 mm with the parameters N _e ～ 10¹⁹?10²⁰ cm^?3 and T _e ～ 100 eV.     

SILEX-I装置上激光-团簇聚变实验中子产额测量

 超短超强脉冲激光与CD4团簇相互作用可以产生高能量的氘离子,从而产生DD聚变中子,这种团簇聚变中子源有着非常广阔的应用前景。在SILEX-I 100 TW飞秒激光装置上,超短超强脉冲激光与CD₄团簇相互作用实现了DD核聚变。团簇聚变的中子产额是实验中最为重要的物理量,在实验中采用高灵敏的中子探测器对团簇聚变产生的中子进行了测量,在现有实验条件下测得中子产额为10³。     

Observation of subpicosecond x-ray emission from laser-cluster interaction

We present the first experimental evidence of the subpicosecond duration of x-ray pulses emitted from laser-irradiated clusters, demonstrating the suitability of such a debris free target for ultrafast x-ray science applications. The K-shell emission (approximately 3 keV) from large Ar clusters (6 x 10(5) to 4 x 10(6) atoms) is time resolved, when irradiated by ultrashort (40 fs to 5 ps) and intense laser pulses (10(15-17) W/cm2). The observations are supported by hydrodynamical and collisional-radiative calculations, that reproduce the extremely short x-ray pulse duration.     

Rescattering mechanism of weak decays of double-charm baryons

The doubly charmed baryon Ξ_(cc)~(++) was recently observed by LHCb via the decay processes ofΞ_(cc)~(++)→∧_c~+K~-π~+π~+ and Ξ_c~+π~+. These discovery channels were successfully predicted in a framework in which the short-distance contributions are calculated under the factorization hypothesis and the long-distance contributions are estimated using the rescattering mechanism for the final-state-interaction effects.In this paper,we illustrate the above framework in detail by systematic studies on the two-body baryonic decays B_(cc)→B_cP involving the doubly charmed baryons B_(cc)=(Ξ_(cc)~(++),Ξ_(cc)~+,Ω_(cc)~+),the singly charmed baryons B_c=(B_3,B_6) and the light pseudoscalar mesons P=(π,K,η_(1,8)).     

Rescattering effects in hadron-nucleus and heavy-ion collisions

We review the extension of the factorization formalism of perturbative QCD to coherent soft rescattering associated with hard scattering in high energy nuclear collisions. We emphasize the ability to quantify high order corrections and the predictive power of the factorization approach in terms of universal non-perturbative matrix elements. Although coherent rescattering effects are power suppressed by the hard scales of the scattering, they are enhanced by the nuclear size and could play an important role in understanding the novel nuclear dependence observed in high energy nuclear collisions.Arrival of the final proofs: 22 July 2005PACS: 12.38.Bx, 12.39.St, 24.85. + p