Outer zone electrons

Spatial and temporal behavior of high energy trapped electrons in outer zone of magnetospher

Dynamics of Excited Electrons in Copper: Role of Auger Electrons

Within a theoretical model based on the Boltzmann equation, we analyze in detail the structure of the unusual peak recently observed in the relaxation time in Cu. In particular, we discuss the role of Auger electrons in the electron dynamics and its dependence on the d-hole lifetime, the optical transition matrix elements and the laser pulse duration. We find that the Auger contribution to the distribution is very sensitive to both the d-hole lifetime tau_h and the laser pulse duration tau_l and can be expressed as a monotonic function of tau_l/tau_h. We have found that for a given tau_h, the Auger contribution is significantly smaller for a short pulse duration than for a longer one. We show that the relaxation time at the peak depends linearly on the d-hole lifetime, but interestingly not on the amount of Auger electrons generated. We provide a simple expression for the relaxation time of excited electrons which shows that its shape can be understood by a phase space argument and its amplitude is governed by the d-hole lifetime. We also find that the height of the peak depends on both the ratio of the optical transition matrix elements R=|M_{d \to sp}|^2/|M_{sp \to sp}|^2 and the laser pulse duration. Assuming a reasonable value for the ratio, namely R = 2, and a d-hole lifetime of tau_h=35 fs, we obtain for the calculated height of the peak Delta tau_{th}=14 fs, in fair agreement with Delta tau_{exp} \approx 17 fs measured for polycrystalline Cu.Comment: 6 pages, 6 figure

Means and method for calibrating a photon detector utilizing electron-photon coincidence

An arrangement for calibrating a photon detector particularly applicable for the ultraviolet and vacuum ultraviolet regions is based on electron photon coincidence utilizing crossed electron beam atom beam collisions. Atoms are excited by electrons which lose a known amount of energy and scatter with a known remaining energy, while the excited atoms emit photons of known radiation. Electrons of the known remaining energy are separated from other electrons and are counted. Photons emitted in a direction related to the particular direction of scattered electrons are detected to serve as a standard. Each of the electrons is used to initiate the measurements of a time interval which terminates with the arrival of a photon exciting the photon detector. Only the number of time intervals related to the coincidence correlation and of electrons scattered in the particular direction with the known remaining energy and photons of a particular radiation level emitted due to the collisions of such scattered electrons are counted. The detector calibration is related to the number of counted electrons and photons

Transport of secondary electrons and reactive species in ion tracks

The transport of reactive species brought about by ions traversing tissue-like medium is analysed analytically. Secondary electrons ejected by ions are capable of ionizing other molecules; the transport of these generations of electrons is studied using the random walk approximation until these electrons remain ballistic. Then, the distribution of solvated electrons produced as a result of interaction of low-energy electrons with water molecules is obtained. The radial distribution of energy loss by ions and secondary electrons to the medium yields the initial radial dose distribution, which can be used as initial conditions for the predicted shock waves. The formation, diffusion, and chemical evolution of hydroxyl radicals in liquid water are studied as well.Comment: 7 pages 4 figure

Magnetospheric electrons

Coupling of source, transport, and sink processes produces a fairly accurate model for the macroscopic structure and dynamics of magnetospheric electrons. Auroral electrons are controlled by convective transport from a plasma sheet source coupled with a precipitation loss due to whistler and electrostatic plasma turbulence. Outer and inner zone electrons are governed by radial diffusion transport from convection and acceleration sources external to the plasmapause and by parasitic precipitation losses arising from cyclotron and Landau interactions with whistler and ion cyclotron turbulence

Coronal Electron Distribution in Solar Flares: Drift-Kinetic Model

Using a model of particle acceleration and transport in solar flares, we investigate the height distribution of coronal electrons by focusing on the energy-dependent pitch-angle scattering. When pitch-angle scattering is not included, the peak heights of loop-top electrons are constant, regardless of their energy, owing to the continuous acceleration and compression of the electrons via shrinkage of magnetic loops. On the other hand, under pitch-angle scattering, the electron heights are energy dependent; intermediate energy electrons are at a higher altitude, whereas lower and higher energy electrons are at lower altitudes. This implies that the intermediate energy electrons are inhibited to follow the shrinking field lines to lower altitudes because pitch-angle scattering causes efficient precipitation of these electrons into the footpoint and their subsequent loss from the loop. This result is qualitatively consistent with the position of the above-the-loop-top hard X-ray (HXR) source that is located above coronal HXR loops emitted by lower energy electrons and microwaves emitted by higher energy electrons. Quantitative agreement with observations might be achieved by considering primary acceleration before the onset of loop shrinkage and additional pitch-angle scattering via wave-particle interactions.Comment: 18 pages, 6 figures, accepted by Ap