The angular distribution of preequilibrium nucleons emitted in low- and medium-energy heavy-ion reactions is determined from the kinematics of nucleon-nucleon scattering inside the nuclear matter. In calculating the scattering kernels the excitation of the nuclear matter has been taken into account through a finite-temperature Fermi distribution of the nucleons. Neutron angular distribution in ${}^{12}{\mathrm{C}+}^{165}\mathrm{Ho}$ reaction at 300 MeV incident energy and ${}^{20}{\mathrm{N}+}^{165}\mathrm{Ho}$ reaction at 600 MeV is calculated from two-body scattering kinematics and compared with the experimental data. The present calculations reproduce the experimental data fairly well in both cases. It has been found that in heavy-ion reactions the initial distribution of nucleons plays a significant role in determining the angular distributions.

Analyses using simplified coupled-channels models have been unable to describe the shape of the previously measured fusion barrier distribution for the doubly magic ${}^{16}\mathrm{O}{+}^{208}\mathrm{Pb}$ system. This problem was investigated by remeasuring the fission excitation function for ${}^{16}\mathrm{O}{+}^{208}\mathrm{Pb}$ with improved accuracy and performing more exact coupled-channels calculations, avoiding the constant-coupling and first-order coupling approximations often used in simplified analyses. Couplings to the single- and 2-phonon states of ${}^{208}\mathrm{Pb},$ correctly taking into account the excitation energy and the phonon character of these states, particle transfers, and the effects of varying the diffuseness of the nuclear potential, were all explored. However, in contrast to other recent analyses of precise fusion data, no satisfactory simultaneous description of the shape of the experimental barrier distribution and the fusion cross sections for ${}^{16}\mathrm{O}{+}^{208}\mathrm{Pb}$ was obtained.

We investigate the strange electric and magnetic form factors of the nucleon in the framework of heavy baryon chiral perturbation theory to third order in the chiral expansion. All counterterms can be fixed from data. In particular, the two unknown singlet couplings can be deduced from the parity-violating electron-scattering experiments performed by the SAMPLE and the HAPPEX Collaborations. Within the given uncertainties, our analysis leads to a small and positive electric strangeness radius, $〈r_{E,s}^2〉=(0.05\mathrm{}\pm 0.09)\hspace{0.5em}{\mathrm{fm}}^2.$ We also deduce the consequences for the upcoming MAMI A4 experiment.

Using a flat-crystal x-ray spectrometer designed for low-energy photons from radioactive sources, the K-shell internal ionization and excitation (K-IIE) in the β decay of ${}^{35}\mathrm{S}$ has been investigated by measuring chlorine K x rays from carefully purified ${}^{35}\mathrm{S}$ sources. We have succeeded for the first time in obtaining a high-resolution spectrum of the $K\alpha$ x-ray group emitted after the β decay of ${}^{35}\mathrm{S},$ which consists of at least six lines, indicating that multiple ionizations and excitations including L and M shells are dominant in the K-IIE process during the β decay of low-Z nuclides. The K-hole creation probability for ${}^{35}\mathrm{S}$ determined is $(2.8\mathrm{}\pm 0.5)\times {10}^{-3}$ per decay, which agrees well with the previous result by Rubinson and Howland within the standard deviation. The comparison with available theoretical calculations is also given.

Pion-nucleon scattering up to a pion laboratory kinetic energy of 700 MeV is described by a Poincaré invariant, instant form model. The model is constructed in a space spanned by single-baryon states $|B〉,$ where B is the nucleon, or any resonance that contributes in the energy range considered; and by meson-baryon states $|\mu B〉,$ where $|\mu B〉=|\pi N〉,$ $|\pi \Delta 〉$, or $|\eta N〉.$ The model specifies a mass operator in the form ${M=M}_0+U,$ where $M_0$ is a noninteracting mass operator and U contains the interactions. The $〈\pi N|U|\pi N〉$ potentials are derived from N, $\Delta ,$ $\sigma ,$ and $\rho$ exchange processes. The vertex interactions $〈\mu B|U|B^{\prime }〉$ are derived from field theory interaction Hamiltonians. Coupling to the inelastic channels, $|\pi \Delta 〉$ and $|\eta N〉,$ is provided by a $〈\pi N|U|\pi \Delta 〉$ transition potential due to nucleon exchange; and by interactions of the form $\mu BB^{″}{\mu }^{\prime }{B}^{\prime }.$

The results of an experimental and theoretical study of the inertias and alignments of superdeformed bands (SD) in $A\sim 190$ nuclei are presented. We show that $A\sim 190\mathrm{SD}$ bands tend to be distributed among three groups characterized by their alignments and the number of unpaired nucleons. The alignments cluster around integer values ($i\approx -1,0,1,$ relative to the reference chosen for this study), but the distribution is not strongly peaked: rather it is relatively “broad” compared with the separation, suggesting that the “strict” quantized alignments observed in some nuclei are not a systematic feature of all $A\sim 190\mathrm{SD}$ bands. We further show that mean-field calculations reproduce the general experimental properties and give the three band groups seen in experiment, but they do not generally reproduce the specific alignment of SD band pairs; nor, in general, do they give “good” identical bands.

We review the rationale for basing the calculation of collective motion on the periodic solutions of the time-dependent Hartree-Fock mean field. With suitable discretization, we find a family of these solutions and we apply a simple quantization rule. Results are presented for ${}^4\mathrm{He}$ and ${}^{16}\mathrm{O}$.

We compare recent CEBAF data on inclusive electron scattering of 4.05 GeV electrons on nuclei with predictions, based on a relation between structure functions of a nucleus, a nucleon, and a nucleus of point nucleons. The latter contains nuclear dynamics, e.g., binary collision contributions in addition to the asymptotic limit. The agreement with data is good, except in low-intensity regions. Computed ternary collision contributions appear too small for an explanation. We perform scaling analyses in Gurvitz’s scaling variable and find that for $y_G\gtrless 0,$ ratios of scaling functions for pairs of nuclei differ by less than 15–20 % from 1. Scaling functions for $〈y_G〉<0\mathrm{}$ are, for increasing $Q^2,$ shown to approach a plateau from above. We observe only weak $Q^2$ dependence in final-state interactions (FSI), which in the relevant kinematic region is ascribed to the diffractive nature of NN amplitudes appearing in FSI. This renders it difficult to separate asymptotic from FSI parts and seriously hampers the extraction of $n\left(p\right)\mathrm{}$ from scaling analyses in a model-independent fashion.

The fusion evaporation-residue cross sections for ${}^{32}\mathrm{S}{+}^{184}\mathrm{W}$ have been measured at beam energies of $E_{\mathrm{beam}}=165,$ 174, 185, 196, 205, 215, 225, 236, 246, and 257 MeV using the ATLAS Fragment Mass Analyzer. The data are compared with statistical model calculations and it is found that a nuclear dissipation strength, which increases with the excitation energy, is required to reproduce the excitation function. A comparison with previously published data shows that the dissipation strength depends strongly on the shell structure of the nuclear system.

Recently published data from GANIL, Rivet et al., provide complete charge distributions and kinetic energy determinations for fragments from two reactions at the same excitation energy but different masses. An alternative interpretation, based on the concept of residues, is offered to account for the observed trends.

Shell-model and deformed Hartree-Fock plus BCS calculations are reported for even-even nuclei ${}^{18-30}\mathrm{O},$ ${}^{18-36}\mathrm{Ne},$ and ${}^{20-42}\mathrm{Mg};$ shell-model calculations additionally included ${}^{38,40}\mathrm{Ne}$ and ${}^{44,46,48}\mathrm{Mg}.$ Ground-state binding energies and $2_1^{+}$ quadrupole moments are calculated by both models. Shell-model calculations, aided by a new truncation method, include $2_1^{+}$ excitation energies and magnetic moments. Hartree-Fock calculations with SkI6, RATP, $Z_{\sigma }^{*},$ and SkX Skyrme forces include ground-state deformations and rms radii; SkI6 gives the best overall agreement with experiment. The two models are compared with each other and with experiment. Two-neutron separation energies, evidence for a neutron halo or skin in heavy O isotopes, and deformation of Ne and Mg isotopes are discussed. Both models indicate disappearance of the shell gap at $N=28\mathrm{}$ (Mg), and the shell model does so additionally at $N=20\mathrm{}$ (Ne and Mg).

The total cross section for the $p\overrightarrow{p}\mathrm{pp}{\pi }^0$ reaction at energies close to threshold is calculated within the frame of chiral perturbation theory, taking into account tree and one loop diagrams up to chiral order $D=2\mathrm{}$. We confirm that (i) the leading order impulse and rescattering terms have opposite signs and their overall contributions to chiral order $D=1\mathrm{}$ underestimates the cross section by a factor of 3, and (ii) one loop contributions are substantially larger than lower order contributions, indicating that the heavy fermion formalism power series expansion converges very slowly, and therefore, may not be suitable to apply to pion production in $\mathrm{NN}$ collisions.

We study the bremsstrahlung radiation of a tunneling charged particle in a time-dependent picture. In particular, we treat the case of bremsstrahlung during $\alpha$ decay and show deviations of the numerical results from the semiclassical estimates. A standard assumption of a preformed $\alpha$ particle inside the well leads to sharp high-frequency lines in the bremsstrahlung emission. These lines correspond to “quantum beats” of the internal part of the wave function during tunneling arising from the interference of the neighboring resonances in the open well.

An extensive study of dynamically emitted charged particles was carried out within the framework of a semiclassical transport model. Several systems having different total mass and asymmetry were studied over a wide range of incident energies. It was found that dynamical emission occurring in heavy-ion collisions is the signature of a smooth transition between the low-energy reaction mechanism (deep inelastic model) and the high-energy reaction mechanism (participant-spectator model).

Continuum effects in the weakly bound nuclei close to the drip line are investigated using the analytically soluble Pöschl-Teller-Ginocchio potential. Pairing correlations are studied within the Hartree-Fock-Bogoliubov method. We show that both resonant and nonresonant continuum phase space is active in creating the pairing field. The influence of positive-energy phase space is quantified in terms of localizations of states within the nuclear volume.

The cross sections and angular correlations for neutron emission to various states in the residual nucleus, following the ${}^{13}\mathrm{C}{(e,e}^{\prime }n)$ reaction, have been measured over the excitation energy range 8–27 MeV at the effective momentum transfer of 0.35 ${\mathrm{fm}}^{\mathrm{-}1}$. In the pygmy resonance, neutron emission leads predominantly to the ground and first excited states of ${}^{12}\mathrm{C},$ while in the giant resonance it leads to population of two higher excited states (12.71 MeV, $T=0;$ 15.11 MeV, $T=1).\mathrm{}$ This is the first direct observation for neutron population of these states. The isospin assignments of the resonances are made as a result of the observed decays. The branching ratio of the transition to the $T=1\mathrm{}$ states compared to the total cross section for neutron emission is found to be $19\pm 5\%,$ which is inconsistent with the theoretical predictions of about 50%. Both isospin splitting and the relative $T_{<}$ and $T_{>}$ strengths of the giant resonance are obtained for the neutron decay. The angular-correlation parameters for the decay of the giant dipole resonance are very similar for ${}^{13}\mathrm{C}$ and ${}^{12}\mathrm{C},$ which provides some support for a weak coupling model in which the giant resonance for ${}^{13}\mathrm{C}$ proceeds via core excitations in ${}^{12}\mathrm{C}.$

The nuclear central density is calculated from the nuclear charge-density parameters measured by elastic electron scattering and muonic atom spectroscopy. The nucleon number and asymmetry dependences of the obtained nuclear central density are discussed based on the macroscopic description of nuclei. It is shown that the nuclear central density decreases slowly as the nucleon number or the nuclear asymmetry increases. The proton number and neutron number dependences of the nuclear central density show some structure that seems like the shell effect, since density peaks are formed around the proton and neutron magic numbers. The data fit to the nuclear half density radii measured by muonic atom spectroscopy yields the nuclear radius constant $r_0=1.141\mathrm{}\hspace{0.5em}\mathrm{fm}$, and the data fit to the calculated nuclear central densities gives an estimation for the nuclear matter incompressibility $K_0$ in the range around 220–250 MeV.

The deformation-driving properties of the $h_{9/2}$ configuration in the ${}^{171}\mathrm{Ta}$ nucleus are discussed in view of the transition probabilities measured for this band. The nucleus of ${}^{171}\mathrm{Ta}$ was populated using the reaction ${}^{159}\mathrm{Tb}{(}^{16}\mathrm{O}{,4n)}^{171}\mathrm{Ta}$ at an incident beam energy of 84 MeV. The recoil distance Doppler shift technique was used for the lifetime measurements. The deformation ${\beta }_2\sim 0.26$ obtained from these measurements remains almost constant with increasing rotational frequency. The calculated transitional quadrupole moments are compared with the total Routhian surface calculations within the cranked Hartree-Fock-Bogoliubov framework. The measured reduced transition probabilities are compared with those from projected Hartree-Fock microscopic calculations.

Starting from a semiphenomenological analysis of the ${}^{16}{\mathrm{O}+}^{208}\mathrm{Pb}$ elastic scattering data at energies ranging from 78 to 312.6 MeV and using the dispersion relation, we have obtained the energy dependence of the real potential up to 1503 MeV. This real potential was then used with an absorptive potential calculated with a microscopic model, to analyze the elastic scattering at 793 and 1503 MeV. A good agreement between calculated and measured elastic scattering cross sections at 793 MeV corroborates that at this energy the collision is still dominated by collective processes. However, at 1503 MeV, the agreement between theoretical calculations and experiment is poor as expected, showing that the low collective modes are not the “preponderant” channels responsible for absorption anymore.