Simulation of guiding of multiply charged projectiles through insulating capillaries

Recent experiments have demonstrated that highly charged ions can be guided through insulating nanocapillaries along the direction of the capillary axis for a surprisingly wide range of injection angles. Even more surprisingly, the transmitted particles remain predominantly in their initial charge state, thus opening the pathway to the construction of novel ion-optical elements without electric feedthroughs. We present a theoretical treatment of this self-organized guiding process. We develop a classical trajectory transport theory that relates the microscopic charge-up with macroscopic material properties. Transmission coefficients, angular spread of transmitted particles, and discharge characteristics of the target are investigated. Partial agreement with experiment is found

Fragmentation of Positronium (Ps) in collision with Li ion

Fragmentation of ground state ortho Positronium (Ps) in collision with Li ion (Li+) is studied in the framework of post collisional Coulomb distorted eikonal approximation (CDEA) for the target elastic case . The present model takes account of the two center effect on the ejected e which is crucial for a proper description of the projectile ionization involving an ionic target. Both the fully differential (TDCS) and the doubly differential (DDCS) cross sections (energy spectra) are investigated at intermediate and high incident energies. A broad distinct Electron loss peak (ELP) centered around v_e ~ v_p is noted in the e energy spectrum in contrast to the sharp ELP for a heavy projectile. Two salient features are noted in the present study: i) the shift of the e DDCS peak (summed over e+ angles) towards higher ejection energy with respect to half the residual energy of the system, ii) comparison of the e& e+ energy spectra reflect a strong e - e+ asymmetry with respect to the ratio v_e/v_p =1 >. Both these features could be attributed to the post collisional two center effect on the e due to its parent nucleus (e+) and the screened target ion . Two different wave functions of the Li ion are chosen in order to test the sensitivity of the present results with respect to the choice of the wave function.Comment: 19 pages, 7 figure

Relativistic time dilatation and the spectrum of electrons emitted by 33 TeV lead ions penetrating thin foils

We study the energy distribution of ultrarelativistic electrons produced when a beam of 33 TeV Pb$^{81+}$(1s) ions penetrates a thin Al foil. We show that, because of a prominent role of the excitations of the ions inside the foil which becomes possible due to the relativistic time dilatation, the width of this distribution can be much narrower compared to the case when the ions interact with rarefied gaseous targets. We also show that a very similar shape of the energy distribution may arise when 33 TeV Pb$^{82+}$ ions penetrate a thin Au foil. These results shed some light on the origin of the very narrow electron energy distributions observed experimentally about a decade ago.Comment: Four pages, two figure

Transparency in the processing of temporal ambiguity: The case of embedded tense

We report the results of one acceptability rating study and two self-paced reading studies on the form-meaning mismatch in the interpretation of past-under-past in complement clauses in English. Across the three experiments, we find an off-line and on-line preference for the backward-shifted interpretation, in line with predictions of the structural approach to the ambiguity when assuming a processing preference for morphological transparent interpretation

Reduced Recombination in High Efficiency Molecular Nematic Liquid Crystalline: Fullerene Solar Cells

Bimolecular recombination in bulk heterojunction organic solar cells is theprocess by which nongeminate photogenerated free carriers encounter eachother, and combine to form a charge transfer (CT) state which subsequentlyrelaxes to the ground state. It is governed by the diffusion of the slower andfaster carriers toward the electron donor–acceptor interface. In an increasingnumber of systems, the recombination rate constant is measured to be lowerthan that predicted by Langevin’s model for relative Brownian motion and thecapture of opposite charges. This study investigates the dynamics of chargegeneration, transport, and recombination in a nematic liquid crystallinedonor:fullerene acceptor system that gives solar cells with initial power conversionefficiencies of >9.5%. Unusually, and advantageously from a manufacturingperspective, these efficiencies are maintained in junctions thickerthan 300 nm. Despite finding imbalanced and moderate carrier mobilitiesin this blend, strongly suppressed bimolecular recombination is observed,which is ≈150 times less than predicted by Langevin theory, or indeed, morerecent and advanced models that take into account the domain size andthe spatial separation of electrons and holes. The suppressed bimolecularrecombination arises from the fact that ground-state decay of the CT state issignificantly slower than dissociation

Incrementality in the Processing of Adverbial Order Variations in German

Contribution to Linguistic Evidence 202

Energy and Angular Distribution of Electrons Ejected from Helium by Fast Protons and Electrons: Theory and Experiment

A comprehensive study of the angular and energy distributions of electrons ejected in collisions of fast electrons and protons with He is presented. New experimental results for 300-keV, 1-MeV, and 5-MeV proton impact are reported along with theoretical results for 2-keV electron impact and 100-keV, 300-keV, 1-MeV, and 5-MeV proton impact. The theoretical results, based upon Born approximation with Hartree-Slater initial discrete and final continuum wave functions, show excellent agreement with experimental electron-impact results. Serious discrepancies are found between theory and experiment in the angular distribution of ejected electrons for forward angles for 100- and 300-keV proton impact; the discrepancies decrease markedly for 1-MeV proton impact and are absent for 5-MeV protons. The agreement between theory and experiment for intermediate and backward angles of electron ejection, on the other hand, is uniformly good for all proton impact energies. The reasons for this behavior in terms of a charge-exchange process to a continuum state contributing to electron ejection at forward angles is discussed, and the energy dependence of the data is shown to be consistent with this explanation