Cross-section measurements are reported for the ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(${\pi }^{+}$,${\pi }^{\mathrm{-}}$${)}^{14}$O reaction to the double isobaric analog state and for nonanalog states at 5 to 10 MeV excitation. The extrapolated zero-degree cross sections are 2.3±0.5, 3.7±0.4, 2.2±0.3, and 0.9±0.3 μb/sr at 19.0, 29.1, 64.4, and 79.5 MeV, respectively. The nonanalog-state cross sections are found to rise sharply with increasing beam energy above 50 MeV, in contrast to those of the double isobaric analog state transition. Calculations with a phenomenological isospin-dependent optical potential must include an isotensor term, which accounts for transitions through nonanalog intermediate states or other short-range correlations, in order to describe the energy and angular trends of the data. Microscopic calculations in the second-order distorted-wave impulse approximation fail to reproduce the cross sections near 50 MeV unless the effects of short-range correlations beyond those contained in the model are incorporated.

The decay of ${}_{}{}^{50}{}_{}{}^{}\mathrm{V}$ has been studied with a low-background, three-crystal intrinsic Ge detector operating in a salt mine. The partial half-life for electron-capture decay to the first excited state of ${}_{}{}^{50}{}_{}{}^{}\mathrm{Ti}$ has been estimated to be (2.05±0.49)×${10}^{17}$ yr, and the partial half-life for ${\beta }^{\mathrm{-}}$ decay to the first excited state of ${}_{}{}^{50}{}_{}{}^{}\mathrm{Cr}$ has been estimated to be (8.$2_{\mathrm{-}3.1}^{+13.1\mathrm{}}$)×${10}^{17}$ yr.

We discuss different nuclear structure properties that may lead to spin suppression in magnetic dipole excitations (as well as in Gamow-Teller transitions). We especially compare the triaxial and the axial asymptotic deformation limits and show that the summed B(M1) strength can be quite different in the two cases. A connection between triaxial deformation and spin suppression is established. It is known, however, that modern Hartree-Fock calculations yield axially symmetric solutions for several nuclei which were previously thought to be triaxial. We show that taking into account the effects of higher shells can lead to an enhanced orbital contribution to M1 excitations without affecting ground-state magnetic moments.

The directional correlations of coincident gamma transitions have been measured in ${}_{}{}^{76}{}_{}{}^{}\mathrm{Se}$ following the ${\beta }^{\mathrm{-}}$ decay of ${}_{}{}^{76}{}_{}{}^{}\mathrm{As}$ ($t_{1/2}$=26.4 h) using a spectrometer consisting of two large-volume hyperpure Ge detectors. The measurements were carried out for 24 gamma cascades, 17 of these for the first time. A spin assignment of $3^{+}$ for the 2363 keV level is suggested and many previous spin assignments were confirmed. The multipole mixing ratios, δ, for 16 transitions were extracted from the present results.

We present a semiclassical method to calculate the widths of giant resonances. We solve a mean-field kinetic equation (Vlasov equation) with collision terms treated within the relaxation time approximation to construct a damped strength distribution for collective motions. The relaxation time is evaluated from the time evolution of distortions in the nucleon momentum distribution using a test-particle approach. The importance of an energy dependent nucleon-nucleon cross section is stressed. Results are shown for isoscalar giant quadrupole and octupole motions. A quite important interplay between self-consistent (Landau) and collisional damping is revealed.

The even-odd Xe and Ba isotopes were studied in the averaged multi-j fermion orbit interacting boson-fermion model I. The agreements of the experimental and calculated energy spectra are quite good. The analyses on wave functions indicate that the mixture of fermion orbits increases and the quasiband structure becomes less prominent for the heavier even-odd Xe and Ba isotopes. The B(E2) values for ${}_{}{}^{131}{}_{}{}^{}$,133Xe were calculated and compared with the experimental data.

We combine the cranked Hartree-Fock-Bogoliubov formalism at finite temperature with the random-phase approximation to calculate electromagnetic transition strengths for E1, M1, and E2 transitions for any value of energy and spin of rare-earth nuclei. Our calculations are free of spurious contributions because we successfully remove all Goldstone modes from the random-phase approximation calculations. Using the separable Baranger-Kumar Hamiltonian, we can calculate the response functions for electromagnetic decay without explicit construction of the random-phase approximation eigenmodes. We report numerical results on the transitional nucleus ${}_{}{}^{156}{}_{}{}^{}\mathrm{Er}$, which is prolate or oblate for small or high spin, respectively, and discuss them.

The static path approximation to the partition function of a nucleus is studied for Hamiltonians with quadrupole-quadrupole interactions. The static path approximation yields a higher level density than the finite-temperature Hartree theory due to a better treatment of the deformation degrees of freedom. The level density is further increased when the nucleus has a static deformation. Comparing with the exact partition function of the Elliott SU(3) model, the static path approximation is found to be remarkably accurate and far superior to finite-temperature Hartree theory.

Energy levels and transitions for the nuclei ${}_{}{}^{61}{}_{}{}^{}\mathrm{Ni}$ and ${}_{}{}^{62}{}_{}{}^{}\mathrm{Ni}$ are analyzed within the framework of the geometrical model. Features appropriate to the supersymmetry Osp(4/2,R)×${\mathrm{SO}}^{\mathrm{BF}}$(5), containing the noncompact orthosymplectic superalgebra Osp(4/2,R), are displayed.

The SO(8) dynamical symmetry limit of the Fermion dynamical symmetry model is used to study various aspects of the quasiparticle random phase approximation. The zero frequency modes of the general quasiparticle random phase approximation are given in analytical form. The quasiparticle random phase approximation excitation energy and transition probability are derived in analytical form in the spherical limit of the general SO(8) Hamiltonian.

Real-time finite-temperature Green’s-function methods with a normal pair cutoff approximation and an abnormal pair cutoff approximation are applied to the calculation of liquid-gas and superconducting phase transitions of finite nuclear matter. Finite-size effects are found to lead to a sizable reduction of the critical temperature of the liquid-gas phase transition (6 MeV) as compared to the case of infinite nuclear matter. A critical number of nucleons $N_c$ as well as a critical volume $V_c$ are found. Under the condition N<$N_c$ (or V<$V_c$) the superconducting phase disappears. Dependence of the energy gap for the finite nuclear matter with different sizes is discussed.

Earlier we reported the detection of three events in which ${}_{}{}^{234}{}_{}{}^{}\mathrm{U}$ decayed by Mg-ion emission and 14 events in which it decayed by Ne-ion emission. In a new experiment with a factor of 7 longer exposure time, we have detected 36 Mg fragments and 108 Ne fragments. From the larger number of events, we have made a more accurate determination of the branching ratios relative to alpha decay, taking into account zenith-angle-dependent detection efficiency. The result is ${\log }_{10}$B(Ne/ α)=-12.36±0.05 and ${\log }_{10}$B(Mg/α)=-12.86±0.08.

Branching ratios to the neutron hole states resulting from the decay of the isoscalar giant monopole resonance in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ have been extracted from our previously published data. The results are compared to other experimental data. An upper limit for (semi)direct decay is obtained and compared to recent calculations. Considerable discrepancies are found.

A general formula for the laser-assisted internal conversion coefficient valid for all electronic shells and an approximation for near threshold laser-assisted internal conversion coefficient are deduced. The weak laser field and low frequency limits of the result are discussed. Numerical examples of the approximated, near threshold laser-assisted internal conversion coefficients are also given.

A fit to kaon photoproduction data has been made within the diagrammatic approach. We demonstrate the need to calculate error bounds on the coupling constants derived from least-squares analyses if these couplings are to be compared to those determined in analyses of $K^{\pm }$N data.

It is shown that surface-peaked transition charge densities can be obtained for the first excited $2^{+}$ states of even-mass Ni isotopes by considering core-polarization effects based on a first-order perturbation theory in the standard shell model of the ($p_{3/2}$,$p_{1/2}$,$f_{5/2}$${)}^n$ configurations.

Measurements of γ-ray multiplicity in coincidence with the projectile-like fragments from inelastic collision of ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ on ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$ at 160.5 MeV lab bombarding energy are reported. The experimental multiplicity increases with increasing total kinetic energy loss and shows a plateau above ∼15 MeV while the angular distributions of the projectile-like fragments exhibit an evolution in the shape around the same energy. These effects seem to indicate a transition mechanism from quasielastic to more damped processes that, in medium nuclei, occurs at low energy losses although some features of a direct reaction are still retained.

The renormalized quasielastic response functions of finite nuclei are studied in the σωρ model of quantum hadrodynamics. The Hartree response is calculated using meson fields and nucleon wave functions as obtained in renormalized mean-field theory for closed-shell nuclei. We employ a local-density approximation only for the correlations treated in random-phase approximation. Thus binding-energy effects are included. As expected, the agreement with the data is better than in previous work, where the local-density approximation was used for the entire response.

The random-phase-approximation formalism with good isospin, developed previously for the particle-hole excitations, is extended to the two-particle and two-hole excitations. It is found that the effect of the isospin symmetry on the normal pairing vibrations is of minor importance. In contrast, the giant pairing vibrations are always split among the isospin components. As an illustration we discuss the experimental results for the ${}_{}{}^{112}{}_{}{}^{}\mathrm{Sn}$(p,t) reaction.

A recent calculation by Hill et al. for the electromagnetic dissociation of ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ and ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$ is corrected.