Angular distributions for elastic and inelastic scattering of ${}_{}{}^{16}{}_{}{}^{}$O${+}^{144}$Sm have been measured at bombarding energies E=69.2 and 72.3 MeV. Excitation functions were measured between E=61 and 76.3 MeV at backward angles. The present elastic scattering data plus existing fusion data were adjusted with both energy-independent and energy-dependent optical-model potentials. The energy dependence appears to be consistent with the dispersion relations which correlate the real and imaginary components of the potentials. The potentials behave similarly when coupling to inelastic channels is considered.

The fragmentation of the system ${}_{}{}^{40}{}_{}{}^{}$Ar${+}^{58}$Ni into three heavy nuclei is studied at 15 MeV/nucleon bombarding energy. The kinematic quantities Z,E,p of the fragments are completely measured by three large ionization chambers. Employing a correlation analysis on the fragment momenta p, the fragmentation mechanism is shown to be a fast process. The data are in agreement with the assumption of a prompt breakup process competing with sequential fission, the latter being strongly influenced by the Coulomb residual interaction.

The statistical fission decay properties of the giant dipole, quadrupole, and monopole resonances in ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$ are investigated with the aid of the Hauser-Feshbach model. It is found that the giant quadrupole resonance fission decay probability is as large as that of the giant dipole resonance, at energies higher than the fission barrier. At energies close to the fission barrier, the giant quadrupole resonance fission probability is found to be appreciably larger than that of the giant dipole resonance. The giant multipole resonance fission probability follows closely that of the giant quadrupole resonance. Comparison with the more commonly employed alternative statistical fission model is made.

A vibrational collective model has been used to analyze 15 bound states in ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ excited by inelastic scattering of 500 MeV polarized protons. It is shown that for those states which have surface peaked charge transition densities the collective model describes the shape and magnitude of the angular distributions quite well. The hadronic deformation lengths extracted are shown to be constant over the incident proton energy range of 25–800 MeV with the exception of data at 185 MeV. The average values for the hadronic deformation lengths are used to calculate the ratio of the neutron to proton multipole matrix elements for five states. Elastic scattering and the $3_1^{\mathrm{-}}$, $2_1^{+}$, and $5_1^{\mathrm{-}}$ transitions have also been studied using the relativistic collective model.

The importance of hyperon-nucleon final-state interaction in kaon photoproduction from the deuteron is examined. By calculating the deuteron wave function using the Reid, Paris, or Bonn NN potentials, the uncertainty of this process due to the nucleonic wave function is found to be negligible. The insignificance of off-shell and relativistic effects is demonstrated by employing a completely relativistic wave function and comparing various approximations. We find the influence of the kaon production operator to be the most critical ingredient in this calculation. Final-state effects, which are included via a distorted-wave formalism, involve partial waves up to l=3. They produce a sharp rise of the cross section near threshold resulting in an enhancement by about a factor of 3, but diminish rapidly as the energy increases. Different ΛN potential models show variations of the effect by up to 10%.

Cross sections and polarizations for the (${\pi }^{+}$,$K^{+}$) hypernuclear production reaction are newly formulated in the correct full scheme based on both the elementary spin-nonflip f and the spin-flip g amplitudes, avoiding thus previous approximations and oversimplifications. Importance of this novel formulation is demonstrated for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ targets. Particular states indeed acquire both large cross sections and large polarizations, which has an important bearing on experimental projects.

A microscopic calculation of the first-order s-wave optical potential in pionic atoms which allows the inclusion of the off-shell dependence in momentum of the s-wave πN amplitude is carried out. Binding effects are also properly taken into account. The results obtained, together with those of the second-order optical potential, are in disagreement with phenomenological optical potentials. The results of the paper suggest the need of new and precise experiments on πN scattering at low energies and other experiments which can provide precise values of the πN scattering lengths.

Inclusive differential cross section and analyzing power $T_{20}$ in A(d,p)X at 2.1 GeV and for protons at 0° are presented for the targets ${}_{}{}^1{}_{}{}^{}\mathrm{H}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, Ti, and Sn. In addition, data for ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ at 1.25 GeV are also shown. For all targets the cross-section data show a similarity in shape when plotted as a function of q, the proton momentum in the deuteron frame, each target exhibiting a shoulder near q=0.30–0.35 GeV/c. Likewise, $T_{20}$ values are largely independent of the target’s A value. When compared with higher-energy data for ${}_{}{}^{12}{}_{}{}^{}(\mathit{d}$,p)X, the new results establish the universality of the shoulder over the energy range 1.25–7.4 GeV, as well as the energy independence of $T_{20}$. The ${}_{}{}^1{}_{}{}^{}(\mathit{d}$,p)X data are compared with the results of a nonrelativistic calculation of the six lowest-order graphs of the process using elastic, on-shell NN amplitudes and the Paris NN potential deuteron wave function. The calculated cross sections have no shoulder at either of the two energies of this experiment; the observed behavior of $T_{20}$ is reproduced qualitatively only. Comparisons with ${}_{}{}^2{}_{}{}^{}(\mathit{p}$,2p) and ${}_{}{}^2{}_{}{}^{}(\mathit{e}$,e’p) data are made and various possible origins for the anomalous shoulder discussed, including π rescattering, Δ excitation, and a six quark component in the deuteron.

A level scheme of ${}_{}{}^{148}{}_{}{}^{}\mathrm{Pm}$ up to 800 keV is deduced from gamma-ray coincidence data and published particle transfer data. Approximately 106 gamma-ray transitions have been placed between 36 levels. We have identified three levels below 500 keV in excitation which decay to both the ground state and to the isomeric level at 137 keV. The presence of these levels guarantees that ${}_{}{}^{148}{}_{}{}^{}\mathrm{Pm}_{}^{\mathrm{g}}{}_{}{}^{}$,m are in thermal equilibrium during the s process. The s-process neutron density inferred from the branch point at ${}_{}{}^{148}{}_{}{}^{}\mathrm{Pm}$ is deduced to be 3×${10}^8$/${\mathrm{cm}}^3$.

The ${}_{}{}^{30}{}_{}{}^{}\mathrm{Na}$ β decay was studied on-line by means of mass-separation techniques. Gamma-ray, gamma-gamma, neutron-gamma spectra, neutron time-of-flight singles, and γ-coincidence measurements were registered. High-energy neutron branches ($E_n$>2 MeV) were found complementing previously reported data. A ${}_{}{}^{30}{}_{}{}^{}\mathrm{Na}$ β-decay scheme to ${}_{}{}^{30}{}_{}{}^{}\mathrm{Mg}$ bound and unbound states is established. The distribution of the transition strength as a function of the excitation energy for particle-unbound levels in ${}_{}{}^{30}{}_{}{}^{}\mathrm{Mg}$ is compared to shell-model calculations performed in the 0–12 MeV excitation energy range. An overall renormalization yields a B(GT) quenching factor of 0.28 substantially lower than generally observed in this mass region. Three levels in ${}_{}{}^{29}{}_{}{}^{}\mathrm{Mg}$ which are strongly populated via the 1n channel are related to negative-parity intruder states.

The decay properties of ${}_{}{}^{153}{}_{}{}^{}\mathrm{Yb}$ and ${}_{}{}^{153}{}_{}{}^{}\mathrm{Tm}$, produced in ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}$ bombardments of ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$, were investigated following on-line mass separation. A decay scheme, incorporating 34 transitions and 25 levels in ${}_{}{}^{153}{}_{}{}^{}\mathrm{Tm}$, was constructed for ${}_{}{}^{153}{}_{}{}^{}\mathrm{Yb}$. It establishes the $s_{1/2}$ proton level in ${}_{}{}^{153}{}_{}{}^{}\mathrm{Tm}$ to be isomeric at an excitation energy of 43.2 keV. The α-decay branch of the $h_{11/2}$ ${}_{}{}^{153}{}_{}{}^{}\mathrm{Tm}$ ground state was determined to be 91±3%. In addition, a partial decay scheme was put together for the 9% ${\beta }^{+}$ branch. About 66% of this ${\beta }^{+}$ decay proceeds to the $h_{9/2}$ neutron state located at 299.3 keV in ${}_{}{}^{153}{}_{}{}^{}\mathrm{Er}$. Only one transition, 266.5 keV, could be assigned to the ${\beta }^{+}$ decay of the ${}_{}{}^{153}{}_{}{}^{}\mathrm{Tm}$ $s_{1/2}$ isomer; it is suggested that the γ ray deexcites the $p_{3/2}$ neutron level to the $f_{7/2}$ ${}_{}{}^{153}{}_{}{}^{}\mathrm{Er}$ ground state. Based on the intensity of this 266.5-keV γ ray, the isomer’s α branch was estimated to be ∼93%.

Reduced transition probabilities of B(M1) and B(E2) are determined up to spin (23/2 on the basis of a Coulomb excitation experiment. Strong signature-dependent staggering was observed for ΔI=1 M1 transition probabilities. In contrast, there was no significant signature dependence observed for ΔI=1 and ΔI=2 E2 transition probabilities as well as for level energies. We carried out a rotating-shell-model calculation with the γ degree of freedom. The origin of the unexpected signature dependence of the B(M1) is shown to be due to the characteristic coherence between the orbital and the spin contributions. We also show that the coupling with the γ-vibrational phonons makes it possible to reproduce the absolute values of the B(M1) at high-spin states without using the phenomenological $g_R$. Both the stretched and nonstretched B(E2)’s are well reproduced in the rotating shell model without assuming triaxiality.

A geometric interpretation of effective interacting boson approximation Hamiltonians describing series of isotopes is carried out. It is shown that a recently introduced SO(5) dynamical symmetry Hamiltonian, which describes the Ru region with fixed parameters for all isotopes, gives rise to a sharp shape transition from spherical to γ-unstable nuclei. Moreover, it is shown that the SO(6), SU(3), and U(5) interacting boson approximation symmetries may display transitional behavior when studied as a function of boson number. A set of constraints in the parameter space are derived, in order for the standard geometrical interpretation of these symmetries to hold.

The isoscalar monopole (E0) and quadrupole (E2) transition strength of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ is used to study how well the α${+}^{12}$C cluster model works for explaining the strength distributions observed up to the isoscalar giant resonance region. The cluster model reproduces 54% of the E0 and 65% of the E2 energy weighted sum-rule strength. A symplectic basis, which naturally reproduces the sum rule, is mixed with the cluster basis to see how much of the missing strength is accounted for. A mixed basis calculation shows that the symplectic basis does not ruin the successful agreement of the cluster model with experiment obtained in the low-energy region and increases the strength by 30% for E0 and 20% for E2 below $E_x$≤40 MeV. It is predicted that both of the E0 and E2 strengths are split into two peaks in the giant resonance region with a greater spread over the excitation energy than expected.

Two kinds of truncations in the microscopic calculation of nuclear low-lying excited states, the many-particle configuration truncation and the single-particle level truncation, are compared. The distinction between them and the advantage of the former over the latter are discussed.

A field theoretical model for the analysis of relativistic nuclear and neutron matter, obtained elsewhere, is studied at nonzero temperature. The Lagrangian describing the microdynamics has been introduced by coupling the nucleons (protons and neutrons) to the σ, π, ω, and ρ meson fields in a renormalizable way. The model is solved in the renormalized Hartree approximation and the free parameters in the Lagrangian are determined in such a way that the empirical properties of symmetric nuclear matter at nuclear density are accurately fitted by the resulting equation of state. We obtain, in particular, a nuclear incompressibility of 225 MeV. The equilibrium neutron star configurations obtained elsewhere with this equation of state, are in very good agreement with the observational evidence. For symmetric nuclear matter, we obtain the behavior of the first-order phase transition and bound states with temperature and we show the corresponding phase diagrams. For neutron matter we obtain the behavior of the various state variables with temperature. These results are useful in the analysis of relativistic heavy ion collisions and have been applied in calculations of neutron star structure, stability, and cooling. In order to facilitate use of the pure neutron matter equation of state at finite temperature in astrophysical calculations, we give a polynomial fit of the corresponding isotherms.

A scheme for shell-model truncations based on diagonalizing and then truncating the separate neutron and proton subspaces and then combining the truncated subspaces together for rediagonalization is described and evaluated. Projected m-scheme techniques are used for these calculations and aspects of this technique relevant to this application are discussed. Detailed calculations are made for ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ and ${}_{}{}^{21}{}_{}{}^{}\mathrm{Ne}$. The truncated results for level schemes, B(E2) values, and wave-function amplitude distributions are compared with the results of calculations in the analogous full shell-model basis spaces. The results suggest that the neutron-proton ‘‘weak-coupling’’ approach may be an effective truncation scheme even though it is known that the n-p interaction has a dominating influence on these nuclei.

The multiplicity of neutron emission in ${}_{}{}^{12}{}_{}{}^{}\mathrm{induced}$ nuclear reactions with ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$, ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$, ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$, and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ was measured directly on-line using a Gd-loaded scintillation neutron multiplicity counter with 1 m diameter recording single neutrons with a registration efficiency of about 80%. Using a well-focused carbon beam one could measure up to about 30 neutrons per nuclear interaction directly, when the neutron multiplicity counter was triggered with a prompt fission fragment. For ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ and ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ targets, fission was observed to follow compound-nucleus formation, whereas in the cases of ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$, fission following incomplete fusion was seen to contribute also. An average multiplicity of ν¯=(4±1) neutrons was measured for incomplete fusion, while for complete fusion, ν¯ varied between 8 and 12, depending on target and bombarding energy. The results complement measurements of Viola et al. on fragment-angular correlations and agree with them.

The conditions for occurrence of the ‘‘inverted’’ signature dependence of B(M1), that is, the enhancement of transitions from the unfavored states, in natural-parity rotational bands are discussed based on the rotating shell model. An example of coexistence of the inverted and the normal signature dependence in an axially symmetric nucleus due to the change in $g_{\mathrm{RPA}}$ associated with the band crossing is presented.

Forward angle spectra of the ${}_{}{}^{208}{}_{}{}^{}(\mathit{p}$,n) reaction at $E_p$=200 MeV are analyzed within a microscopic model assuming that the measured cross section is a result of correlated one-particle–one-hole spin-isospin transitions only. We find that the data are essentially in agreement with the strength predictions of the random-phase approximation. We also find that the observed shapes of the spectra can only be explained by introducing a strongly asymmetric damping of the collective spin-flip modes.