Inelastic shadowing effects in multiple scattering

The projectile-nucleon scattering amplitudes used as input into multiple scattering theories of projectile-nucleus scattering naturally include the effects of coupling to inelastic (i.e., production) channels. We employ a multichannel separable potential to describe the projectile-nucleon interaction and show that within the fixed nucleon framework we can obtain the nuclear elastic scattering amplitude. This includes terms outside the conventional formalisms, corresponding to intermediate propagation in the inelastic channels both above and below inelastic threshold. We refer to this as inelastic shadowing. In a two-channel approximation, we show that knowledge of the projectile-nucleon elastic scattering phase shifts plus specification of the inelastic threshold energy are sufficient to determine the off-shell coupled-channel transition matrix, implying that the nuclear amplitude can be calculated within this model without any detailed information about the inelastic channels. We study this solution quantitatively for some model problems and for pion scattering, with the general result that inelastic shadowing can be significant whenever the elementary interaction has important channel coupling. For pion scattering in the energy regime characterized by strongly absorptive resonances, we find, for example, that the effect of inelastic shadowing is much more important than that due to two-nucleon correlations.     

Antiproton-Nucleus Interaction and Coulomb Effect at High Energies

The Coulomb effect in high energy antiproton-nucleus elastic and inelastic scattering from ¹²C and ¹⁶O is studied in the framework of Glauber multiple scattering theory for five kinetic energies ranged from 0.23 to 1.83 GeV. A microscopic shell-model nuclear wave functions, Woods-Saxon single-particle wave functions, and experimental pN amplitudes are used in the calculations. The results show that the Coulomb effect is of paramount importance for filling up the dips of differential cross sections. We claim that the present result for inelastic scattering of antiproton-¹²C is sufficiently reliable to be a guide for measurements in the very near future. We also believe that antiproton nucleus elastic and inelastic scattering may produce new information on both the nuclear structure and the antinucleon-nucleon interaction, in particular the p-neutron interaction.     

Color Conductivity at High Resolution: A New Phenomenon of Nuclear Physics

In this paper we discuss in detail the hyothesis that nuclei show extended quark and gluon modes when explored with a high resolution probe. We call this color conductivity at high resolution. We relate color conductivity to the behaviour of proton-proton total and elastic cross sections at high energies. For deep inelastic muon-nucleon scattering we discuss in detail the nuclear evolution equation following from color conductivity and introduced by us previously. The EMC Fe/d data are well described by our theory if due allowance is made for the quoted systematic error. We predict striking effects from color conductivity in the final state of deep inelastic lepton-nucleus scattering. The possibility of making fundamental tests of quantum chromodynamics in leptonnucleus scattering is emphasized. We connect the shadowing phenomenon to the volume and surface terms in the Bethe-Weizsäcker formula for the nuclear binding energy. Finally we point out that deep inelastic scattering on deformed nuclei may be crucial to distinguish between different theories of the EMC effect.     

Universality and the weak neutral current

We consider the possibility that the weak neutral current displays both muon-electron and quark-lepton universality. Such a model contains three parameters which we determine, within limits, from existing data on deep inelastic scattering of neutrinos off nucleons and elastic scattering of neutrinos off leptons. We show that such a model is consistent with other results on elastic neutrino-nucleon scattering and neutrino-induced production of single pions.     

Medium corrections in intermediate-energy nucleon-nucleus scattering

Medium corrections in elastic and inelastic nucleon-nucleus scattering are discussed in the framework of Watson's multiple scattering theory. We derive formulae for the effective interactions to be used in the calculation of elastic and inelastic scattering based on a consistent local-density approximation. We show the numerical results of analyses of the p + ¹⁶O reaction at E_p = 135 MeV.     

Semi-transparent hadrons from multi-channel absorption effects

We analyze the absorption structure of diffractive dissociation discussing simultaneously the elastic and inelastic processes. This approach is motivated by their close interdependence and mutual influence. We show that the results differ significantly from the standard picture of elastic scattering. In particular, protons are shown to have very rich internal structure coupling both to “black” and “transparent” diffractive scattering eigenstates. Proton matter distribution may well be very different from that suggested by the analysis of Chou and Yang. Finally, the indicated asymptotic behaviour is that of a “grey” instead of a “black” disc limit.     

Correlation effects in electron-ion collisions in a strong laser field

We examine elastic and inelastic scattering of electrons by ions in intense laser light. A method of numerical investigation of the scattering characteristics based on regularizing the Coulomb singularity is proposed. We show that over a broad range of parameter values the transport scattering cross section is weakly dependent on the intensity of the high-frequency field. We detect a significant modification of the dependence of the effective inelastic scattering cross section. We also show that the energy exchange with the field is determined by a fairly small group of electrons, called the representative electrons. Finally, we propose a qualitative model that explains our results by the fact that the leading contribution is provided by inelastic collisions of electrons with relatively small impact parameters traversing the region important for the interaction at large angles. Zh. éksp. Teor. Fiz. 115, 463–478 (February 1999)     

Excitation of collective nuclear states by fast particles

The elastic and inelastic scattering of a fast particle by a vibrating nucleus is discussed in the semicalssical approximation. For elastic scattering it is shown that the effect of the vibrations can be described by an effective deformed optical potential which is axially symmetric about the incident direction. Explicit results are obtained for inelastic scattering. In an appendix, the validity of the semiclassical approximation for potential scattering is discussed and numerical tests made.     

Analysis of elastic and inelastic α + <Superscript>24</Superscript>Mg scattering within the <Emphasis Type="Italic">S</Emphasis> matrix model involving regge poles

A generalization of the phenomenological S-matrix model taking into account isolated Regge poles is proposed for simultaneously describing refractive effects in the cross sections for the elastic and inelastic scattering of light nuclei. The cross sections for elastic α + ²⁴Mg scattering are analyzed at energies of 50, 54, 65.7, 81, and 119 MeV. The analysis of the cross sections for elastic scattering is supplemented with an analysis of the inelastic scattering of alpha particles that is accompanied by the excitation of the first excited state (2⁺) of ²⁴Mg nuclei. It is shown that the proposed model makes it possible to describe satisfactorily all of the aforementioned cases of elastic and inelastic scattering, correctly reproducing the refraction Airy structures and anomalous large-angle scattering that are observed at large scattering angles.     

Isotope-disorder-induced line broadening of phonons in the Raman spectra of SiC

The width of phonon lines in the Raman spectra of ideal isotopically pure solids is determined by inelastic scattering processes. In solids that contain a mixture of different isotopes of one atomic constituent, elastic scattering due to isotopic mass disorder opens up decay channels that result in additional line broadening. We use different polytypes of SiC with an associated number of Raman active modes in order to experimentally validate the proportionality between linewidth and phonon density of states predicted by a simple elastic scattering theory.     

Large-angle scattering of heavy ions: (II). General structure of inelastic cross section

Closed-form expressions are derived for the differential cross section of inelastic heavy-ion scattering at large angles. The inelastic transition amplitude given by the distorted-waves theory for excitation of low-lying collective states is evaluated by an extension of analytic methods developed in the preceding paper for elastic large-angle scattering. The very close relation between the inelastic and elastic cross sections is displayed. In particular it is shown that the angular distributions have a universal form, and that the backward-angle inelastic excitation function has, aside from a slowly varying overall energy dependence, an oscillatory gross structure of diffractive origin which is nearly identical to that of the elastic excitation function, irrespective of the physical mechanism involved.     

Elastic and inelastic diffraction of Mössbauer γ-rays from KCN

Mössbauer γ-ray diffraction was used to discriminate between the elastic and inelastic scattering intensities from the (1 1 1) to (5 5 5) Bragg reflections of a single crystal of KCN. The energy resolution of our experiment was 28 neV. We observe pronounced inelastic peaks at each Bragg point, while the elastic scattering dies out rapidly due to a large Debye-Waller factor. Thus in case of (4 4 4) and (5 5 5) the inelastic scattering is larger in magnitude than the elastic one.     

Elastic scattering and surface effects on Auger electron angular distribution and attenuation law

We have studied, through Monte Carlo (MC) simulations, the effect of elastic scattering and the presence of a real surface on the angular distribution and attenuation of the no-energy-loss electron emission. We performed two kinds of MC approaches, with and without surface, altering the ratio among elastic and inelastic scattering cross sections to enhance the elastic scattering effect. We found that angular distribution is always affected by the elastic scattering, meanwhile the attenuation law shape is only altered in the presence of a real surface and elastic scattering together. We also compared simulation results with analytical model predictions.     

Combined nuclear-molecular resonance inelastic scattering of x rays

We report on theoretical and experimental studies of nuclear inelastic scattering in a molecular crystal, whose atoms experience both molecular and lattice vibrations. In this case scattering proceeds as combined nuclear-molecular resonance inelastic scattering. The lattice vibrations give rise to inelastic scattering around the molecular resonances with an energy dependence identical to that around the nuclear resonance. The incoherent nature of the scattering in the molecular resonances results in a proper balance of elastic and inelastic components, which has important implications for studies of heterogeneous systems.     

Two component analysis of the inelastic overlap function

We analyse ISR pp elastic data and show that much of the structure of the inelastic overlap function can be attributed to absorptive effects. The “unabsorbed” function can be expressed as the sum of two exponentials (or two Gaussians in b-space) whose behaviours suggest they correspond to the diffractive and multiperipheral components of inelastic scattering. Although the net increase in cross section is peripheral, the diffractive component is essentially central.     

Role of elastic scattering in electron dynamics at ordered alkali overlayers on Cu(111)

Scanning tunneling spectroscopy of p(2 x 2) Cs and Na ordered overlayers on Cu(111) reveals similar line widths of quasi-two-dimensional quantum well states despite largely different binding energies. Detailed calculations show that 50% of the line widths are due to electron-phonon scattering while inelastic electron-electron scattering is negligible. The mechanism of enhanced elastic scattering due to Brillouin zone backfolding contributes the remaining width.     

Feshbach resonances in the 6Li-40K Fermi-Fermi mixture: elastic versus inelastic interactions

We present a detailed theoretical and experimental study of Feshbach resonances in the ⁶Li-⁴⁰K mixture. Particular attention is given to the inelastic scattering properties, which have not been considered before. As an important example, we thoroughly investigate both elastic and inelastic scattering properties of a resonance that occurs near 155?G. Our theoretical predictions based on a coupled channels calculation are found in excellent agreement with the experimental results. We also present theoretical results on the molecular state that underlies the 155?G resonance, in particular concerning its lifetime against spontaneous dissociation. We then present a survey of resonances in the system, fully characterizing the corresponding elastic and inelastic scattering properties. This provides the essential information to identify optimum resonances for applications relying on interaction control in this Fermi-Fermi mixture.     

Scattering of excitons by excitons in semiconducting quantum well structures

We have theoretically investigated the scattering of excitons by excitons in a two-dimensional semiconducting quantum well system. The scattering cross sections have been calculated using the Born approximation for both the elastic and inelastic scattering of the excitons by excitons. The threshold for inelastic scattering is increased over the value in a bulk semiconductor because of the enhancement of the exciton binding energy by its confinement. The behavior of the scattering cross section as a function of the energy of relative motion of the excitons is different than in the bulk and the cross section is a more sensitive function of the ratio of the electron and hole masses than in the bulk.     

Scattering of excitons by free carriers in semiconducting quantum well structures

We have theoretically investigated the scattering of excitons by free electrons and holes in a two-dimensional semiconducting quantum well system. The scattering cross-sections have been calculated using the Born approximation for both the elastic and inelastic scattering of the excitons by the free carriers. The threshold for inelastic scattering is increased over the value in a bulk semiconductor because of the enhancement of the exciton binding energy by its confinement. The behavior of the scattering cross-section as a function of the energy of relative motion of the free carriers and the excitons is different than in the bulk and the cross-section is a more sensitive function of the ratio of the electron and hole masses than in the bulk. In fact, the scattering of light hole excitons is suppressed relative to that of heavy hole excitons by several orders of magnitude.     

A New Simulation of Track Structure of Low-Energy Electrons in Liquid Water:Considering the Condensed-Phase Effect on Electron Elastic Scattering

A new Monte Carlo simulation of the trade structure of low-energy electrons(10keV) in liquid water is presented.The feature of the simulation is taken into consideration of the condensed-phase effect of liquid water on electron elastic scattering with the use of the Champion model,while the dielectric response formalism incorporating the optical-data model developed by Emfietzoglou et al.is applied for calculating the electron inelastic scattering.The spatial distributions of energy deposition and inelastic scattering events of low-energy electrons with different primary energies in liquid water are calculated and compared with other theoretical evaluations.The present work shows that the condensed-phase effect of liquid water on electron elastic scattering may be of the influence on the fraction of absorbed energy and distribution of inelastic scattering events at lower primary energies,which also indicate potential effects on the DNA damage induced by low-energy electrons.