Conditional charge distributions at very high energies

It is shown that the conditional charge distributions in hadronic collisions approach a zero limiting value in the central region at asymptotic energies, provided the average total multiplicities are unbounded. A limiting charge sum rule, which shows how these distributions follow the initial charges, is established and discussed.     

Binding energies of nuclei and their density distributions in a nonlocal extended Thomas-Fermi approximation

Basic properties of the ground states of spherical nuclei are investigated in a nonlocal extended Thomas-Fermi approximation under the assumption of Skyrme forces. It is shown that, for nuclei occurring near the β-stability line, the binding energies, the root-mean-square radii, and the density distributions found on this basis agree well with experimental data. Binding energies, root-mean-square radii, and density distributions are also calculated for the ground states of nuclei lying far off the β-stability line and for superheavy elements. For the proton, the neutron, and the total particle density, the thickness of the diffuse layer is investigated as a function of the number of neutrons in tin isotopes.     

An analysis of charge multiplicity data at high energies

The mode and the median charged multiplicities are both found to exhibit a similar increasing linear dependence on ln Q for pp, π^±p and K^±p interactions in the interval 1 < ln Q < 3(Q = available c.m. energy in GeV). The values obtained are compared to the predictions of the Nova model and the Chew-Pignotti model.     

Nuclear charge and matter distributions

The experimental methods used to determine nuclear charge and matter distributions are described, together with their theoretical interpretation in terms of nuclear structure.     

Isotopic invariance of fission fragment charge distributions for actinide nuclei at excitation energies above 10 MeV

The fragment mass and energy distributions from the proton-induced fission of compound nuclei ²³³Pa, ^{234,236,237,239}Np, ^{239,240,241,243}Am, and ²⁴⁵Bk at proton energy E _p =10.3 and 22.0 MeV have been experimentally studied. It was revealed that the shapes of the asymmetric fission mass distributions are mainly defined by the proton numbers of compound nuclei and demonstrate only a weak dependence on the neutron ones. The detailed study of the fission fragment mass yields for compound nuclei Np and Am isotopic chains has shown that the asymmetric fission fragment charge distributions calculated within the unchanged charge density hypothesis for nuclei with equal Z _C practically coincide.     

Extended-ion approximation and pressure shifts inF-band energies

Pressure variation of maximumF-band absorption energies in the halides of lithium, sodium and potassium has been investigated employing the extended-ion approximation for the calculation of theF-electron energy eigenvalues and using values of local compressibility in the neighbourhood of theF-centres which include the effect of vacancy and pressure. The results obtained agree with the experimental results.     

Driving potential and fission-fragment charge distributions

We propose an efficient approach to describe the fission-fragment charge yields for actinides based on the driving potential of the fissioning system. Considering the properties of primary fission fragments at their ground states, the driving potential, which represents the potential energies of the system around scission configuration and closely relates to the yields of fragments, can be unambiguously and quickly obtained from the Skyrme energy-density functional together with the Weizsäcker–Skyrme mass model. The fission-fragment charge distributions for thermal-neutron-induced fission and spontaneous fission of a series of actinides, especially the odd–even staggering in the charge distributions, can be well reproduced. Nuclear dynamical deformations and pairing corrections of fragments play an important role in the charge distributions.     

Coulomb energies and charge asymmetry of nuclear forces

Charge-symmetry-breaking potentials suggested in the literature to resolve the discrepancy between calculated Coulomb energy differences of analog states and the experimental values, are considered in detail. We calculate the contributions of these potentials to the ground state energy differences of the mirror nuclei ³He³H, ¹⁵O¹⁵N, ¹⁷F¹⁷O, ³⁹Ca³⁹K and ⁴¹Sc⁴¹Ca. It turns out, due to the short range character of these symmetry-breaking potentials, that their inclusion may resolve the ³He³H difficulty but not the ⁴¹Sc⁴¹Ca discrepancy.     

Mass and charge distributions with correlated exchange

The dependence of the inclusive variancesσ _A ² ,σ _Z/2 andσ _N ² in nuclear collisions is investigated as a function of the correlation coefficient ρ for isospin correlated nuclon exchange on the dinuclear potential energy surface (PES). Variances for neutron-proton cluster exchange (single step process with zero net momentum between the constituents) are also evaluated. This analysis is helpful to understand the nature of the exchange mechanism. There exist a few experimental data which are at variance with either uncorrelated neutron-proton exchange or with isospin correlated exchange. An explanation of this data may possibly lie in coexisting neutron-proton cluster exchange.     

Momentum distributions and separation energies for the valence orbitals of chloromethane

Chloromethane (CH₃Cl) has been studied by binary (e,2e) coincidence spectroscopy at 1200 eV using noncoplanar symmetric kinematics. Separation enerThe (e,2e) results reported in this work have confirmed the nature and symmetry of the final ion states of chloromethane previously assigned by photoel     

Nuclear binding energies and liquid drop parameters in the extended Thomas-Fermi approximation

Using the extended Thomas-Fermi model, we calculate average nuclear binding energies with Skyrme type effective interactions. The total energy is minimized with respect to variations of the nucleon densities without the use of wave functions or adjustable parameters. We obtain binding energies only ～2–7 MeV higher than self consistenly averaged Hartree-Fock energies. By least-square fits we determine the liquid drop parameters of different effective interactions very accurately. Shell effects are added perturbatively and lead to total energies within 5–10 MeV of the exact Hartree-Fock results.     

Surfaces with quenched and annealed disordered charge distributions

We consider surfaces with disordered charge distribution. The disorder can be caused by mobile charges, as for example in mixed lipid bilayers, or by weakly charged surfaces where charge regulation takes place (e.g. carboxyl groups). Using Monte-Carlo simulation methods we find for quenched as well as annealed disordered charge distributions counterion densities close to the surface that are significantly larger than for ordered regularly spaced surface ions. Our field-theoretic results agree well with results obtained from Monte-Carlo simulations of the system. Furthermore, we obtain expressions for the effective interaction between charged colloids and charged rods close to a charged surface and discuss the effect of the surface-ion mobility and polarization charges on the interaction. In general, polarization effects as well as surface-ion mobility lead to a weakening of the effective interaction between charged objects.     

Scaling of pseudorapidity distributions at c.m. energies up to 0.9 TeV

New data are presented on charged particle pseudorapidity distributions for inelastic events produced at c.m. energies \(\sqrt s \) =200 and 900 GeV. The data were obtained at the CERN antiproton-proton Collider operated in a new pulsed mode. The rise of the central density ρ(0) at energies up to \(\sqrt s \) =900 GeV has been studied. A new form of central region scaling is found involving the densityρ _n (0) for charged multiplicityn, namely that the scaled central densityρ _n (0)/ρ(0) expressed as a function ofz=n/〈n〉 is independent ofs. Scaling in the fragmentation region holds to 10–20%, and the small amount of scalebreaking observed here could be accommodated within the framework suggested by Wdowcyk and Wolfendale to account for both accelerator and cosmic ray data.     

Parton distributions in the small-x region within LLX approximation

The solutions of Lipatov-Fadin-Kuraev equation (LFK) within LLX approximation for gluon distributions are studied. The results are based on the semiphenomenological boundary conditions taken from LLQ² analysis. We find, that pure theoretical LLX approach can reproduce the form of singular small-x behaviour of gluon and sea-quark distributions obtained within LLQ²A with singular input parametrizations. Some remarks about shadowing corrections are presented.     

Molecular orbital momentum distributions and binding energies for H2O using an electron impact coincidence spectrometer

The construction and operation of an instrument which uses the techniques of coincidence counting and electron impact spectroscopy is reported for the study of molecular ionization at large momentum transfer in which the two outgoing electrons are detected at 45° to the incident beam. Variation of the incident energy provides binding-energy spectra for Xe, CH₄ and H₂O up to 45 eV. Alternatively variation of the azimuthal angle (symmetric, non-coplanar geometry) gives a measure of the electron momentum distribution for any selected orbital in the binding-energy spectrum. Momentum distributions for the four valence orbitals of H₂O are compared with various wavefunctions from the literature.