Energy spectra of both protons and deuterons emitted following the capture of negative muons by ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ nuclei have been measured for energies above 15 MeV. A limited number of proton-neutron pairs emitted in coincidence were also observed. A simple plane wave impulse approximation (PWIA) model calculation yields fair agreement with the measured proton energy spectra, but underpredicts the measured rate of deuteron production above our energy threshold by a large factor. A more sophisticated PWIA calculation for the two-body breakup channel, based on a realistic three-body wave function for the initial state, is closer to the deuteron data at moderate energies, but still is significantly lower near the kinematic end point. The proton-neutron coincidence data also point to the presence of significant strength involving more than one nucleon in the capture process at high energy transfer. These results indicate that additional terms in the capture matrix element beyond the impulse approximation contribution may be required to explain the experimental data. Specifically, the inclusion of nucleon-nucleon correlations in the initial or final state and meson exchange current contributions could bring calculations into better agreement with our data. A fully microscopic calculation would thus open the possibility for a quantitative test of multinucleon effects in the weak interaction.

We model the NN¯ system at rest as a baryon number zero lump in the Skyrme model including the ω field. We integrate the classical equations of motion from the highly nonperturbative annihilation region into the noninteracting radiation zone. Subsequent coherent state quantization of the radiation field give a good description of the pion spectrum from annihilation at rest.

An energy-dependent and a set of single-energy partial-wave analyses of πd elastic scattering data have been completed. Amplitudes are presented for pion laboratory kinetic energies up to 500 MeV. These results are compared with those found in other recent analyses. We comment on the present database and make suggestions for future work.

Utilizing the ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$(p,n) reaction and a low-energy proton detector ball, beta-delayed proton emission from ${}_{}{}^{24}{}_{}{}^{}\mathrm{Al}$ has been observed in the form of a quasicontinuum of protons from ∼300 to 1100 keV. By making a comparsion with a previously known ${}_{}{}^{24}{}_{}{}^{}\mathrm{Al}$ beta-delayed alpha branching ratio, a branching ratio for beta-delayed proton emission of (1.2±0.3)×${10}^{\mathrm{-}5}$ has been determined.

Measurements of γ-ray singles and γγ-coincidence spectra, γ-ray angular distributions, and Doppler shift attenuation have been made, following the reaction ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$${(}^4$He,pn${)}^{65}$Zn at 30 MeV. The level scheme has been confirmed up to 5773 keV. The spins and parities of the three states at 3227.6, 3785.7, and 4938.0 keV, hitherto uncertain or unknown, are found to be 17/$2^{+}$, 17/$2^{+}$, and 21/$2^{+}$, respectively. The mean lives for these states, for which there is no information available in the literature, have been estimated, and the deduced B(E2) values for the 4938.0→3227.6 (21/$2^{+}$→17/$2^{+}$), 3227.6→2053.5 (17/$2^{+}$→13/$2^{+}$), and 3785.7→2053.5 (17/$2^{+}$→13/$2^{+}$)-keV transitions are all found to be strongly enhanced with respect to the Weisskopf single-particle estimates indicating collectivity in the structure of the concerned states. Evidence is presented in favor of the interpretation of the positive parity states in ${}_{}{}^{65}{}_{}{}^{}\mathrm{Zn}$ with ${\mathit{J}}^{\mathrm{\pi }}$ values 9/$2^{+}$ to 21/$2^{+}$, as arising from the weak coupling of a ${\mathit{g}}_{9/2}$ neutron to the quadrupole excitations of the ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}$ core.

Rotational states have been identified in ${}_{51}{}^{111}{}_{}{}^{}\mathrm{Sb}$ for the first time. Three decoupled (ΔI=2) bands extending to over 1 MeV in rotational frequency have been observed. At the highest frequencies, the ${\mathit{scrJ}}^{\mathrm{}\left(2\right)\mathrm{}}$ moments of inertia for these three bands are seen to decrease steadily to unexpectedly low values; this is interpreted as evidence for a novel form of band termination. One of these bands is interpreted as being based on the π${\mathit{h}}_{11/2}$ orbital coupled to a deformed [(π${\mathit{g}}_{9/2}$${)}^{\mathrm{-}2}$⊗(π${\mathit{g}}_{7/2}$)${]}_{0+}$ state of the ${}_{50}{}^{110}{}_{}{}^{}\mathrm{Sn}$ core. The interaction strength for the alignment of a pair of ${\mathit{h}}_{11/2}$ neutrons has been extracted and compared with calculations. Two possible quasiparticle configurations are discussed for the other decoupled bands. Two strongly coupled (ΔI=1) bands have been identified and both shown to involve the [(π${\mathit{g}}_{9/2}$${)}^{\mathrm{-}1}$⊗(π${\mathit{g}}_{7/2}$${)}^2$] configuration. A large number of spherical states have also been observed, which can be explained on the basis of valence protons coupled to spherical states in the ${}_{}{}^{110}{}_{}{}^{}\mathrm{Sn}$ core.

Measurement of γ, γγ-coincidence, internal conversion electron and γ-ray angular distribution spectra for the ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sn}$(p,nγ${)}^{114}$Sb reaction were made at 7.8 and 8.0 MeV bombarding proton energies with Ge γ-ray and superconducting magnetic lens-plus-Si(Li) electron spectrometers. The energies and relative intensities of 74 ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sb}$ γ rays, as well as the internal conversion coefficients of 31 ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sb}$ transitions have been determined and new angular distribution data have been obtained for 26 γ rays. From this information, a more complete and consistent level scheme has been deduced. Spin and parity values have been determined from the internal conversion coefficients, Hauser-Feshbach analysis of the (p,n) reaction cross sections, and the γ-ray angular distributions. The low-lying levels were grouped into proton-neutron multiplets and the energy splitting of these multiplets have been interpreted in terms of the parabolic rule.

Two new high-lying level sequences of negative parity have been identified in the odd-proton nucleus ${}_{}{}^{81}{}_{}{}^{}\mathrm{Rb}$ by in-beam γ-ray spectroscopy using the reactions ${}_{}{}^{79}{}_{}{}^{}\mathrm{Br}$(α,2n) at 27 MeV and ${}_{}{}^{68}{}_{}{}^{}\mathrm{Zn}$${(}^{19}$F,α2n) at 72 MeV. One sequence, dominated by M1 transitions, is interpreted as a three-quasiparticle band predominantly containing a neutron in the ${\mathit{p}}_{1/2}$, ${\mathit{p}}_{3/2}$, or ${\mathit{f}}_{5/2}$ subshell coupled to ${\mathit{g}}_{9/2}$ proton and ${\mathit{g}}_{9/2}$ neutron excitations. The other new level sequence forms the three-quasiparticle extension of the unfavored negative-parity band, but the states decay also by E1 transitions. The signature splitting points to a configuration where an aligned ${\mathit{g}}_{9/2}$ proton pair is involved.

In this paper we address the (charge) longitudinal electromagnetic response for a homogeneous system of nucleons interacting via meson exchanges in the functional framework. This approach warrants consistency if the calculation is carried on order by order in the mesonic loop expansion with random-phase-approximation-dressed mesonic propagators. At the 1-loop order and considering π, ρ, and ω exchanges we obtain a quenching of the response, in line with the experimental results.

A conventional particle-rotor model calculation has been performed for a number of odd-A rare earth nuclei in the mass region A≃160–190. A detailed analysis of the results of the calculation has been made. It shows that the positive parity bands which exhibit identical dynamical moments of inertia with their even-(A-1) neighbors are not at all perturbed by the Coriolis interaction. On the other hand, the positive parity bands which are appreciably perturbed by the Coriolis interaction show ‘‘normal’’ behavior. This feature essentially points out that the core is not polarized in presence of the unpaired valence proton. In case of the negative parity bands, an interesting feature is observed. For most of them, which show identical band behavior, agreement with experimental spectra can be achieved with reasonable values of Coriolis attenuation factor only if their neighboring (A+1) even nuclei are used as cores.

q deformations of the Hamiltonian with SO(6) or U(5) symmetry in the interacting s,d boson model are discussed. The deformations are introduced through q-deformed U(5), SO(3), and the boson pairing algebra SU(1,1). It is shown that the SO(6) or U(5) dynamical symmetry remains after deformation. The deformed Hamiltonian under the two limiting cases can be applied to describe energy spectra of certain isotopes. As examples, energy spectra and some E2 transition rates of even-even ${}_{}{}^{110\mathrm{-}114}{}_{}{}^{}\mathrm{Cd}$, ${}_{}{}^{190\mathrm{-}196}{}_{}{}^{}\mathrm{Pt}$, and ${}_{}{}^{124\mathrm{-}128}{}_{}{}^{}\mathrm{Xe}$ are fitted and compared with the experimental results. Finally, the physical meaning of q deformation is also discussed.

We investigate the relevance of the single particle potential on the theoretical determination of the Landau parameters within the Brueckner-Bethe-Goldstone theory of symmetric nuclear matter. In particular we study the influence of the choice of the single particle potential on their overall trend as well as the fulfillment of the sum rules. At the two-hole level of approximation the single particle continuous choice and the corresponding effective mass give Landau parameters which best satisfy the sum rules. However, the spin-isospin parameter ${\mathrm{G}}_0^{\prime }$ appear small in comparison with phenomenology. A good value can be obtained by a slight enhancement of the effective mass, with respect to the Bruechner value, still keeping the other Landau parameters within the phenomenological boundaries and fulfilling the sum rules fairly well.

The angular momentum projected Tamm-Dancoff approximation is applied to describe eight excited rotational bands of the nucleus ${}_{}{}^{168}{}_{}{}^{}\mathrm{Yb}$ up to very high angular momenta. The good agreement with the experimental data allows us to assign parity and angular momentum to some bands which previously had uncertain assignment. Beside the energy levels, we describe moments of inertia, gyromagnetic factors, and B(E2) transition probabilities along the yrast band. The pairing properties of this nucleus at high spins are discussed in the frame of a symmetry violating wave function. We do not find it necessary to invoke a phase transition to obtain a good agreement with the experimental data at very high spins.

Experimental values of signature splitting in ν${\mathit{i}}_{13/2}$ rotational bands in odd-N even-Z nuclei in the Z=62–78 region are collected and presented. A procedure is introduced to calculate signature splitting within the cranked deformed Woods-Saxon model. In the theoretical treatment, deformation parameters are obtained by minimizing the total Routhians of individual ν${\mathit{i}}_{13/2}$ bands, and the procedure accounts for the possibility that the two signatures have different deformations and pairing gaps. Experimental signature splitting data for ν${\mathit{i}}_{13/2}$ bands in Dy, Er, Yb, Hf, W, and Os nuclei are compared with calculated values. The sensitivity of calculated signature splitting to changes in deformation, pairing, and other model parameters is presented.

A novel information theory based method for determining the density of states from prior information is presented. The energy dependence of the density of states is determined from the observed number of states per energy interval, and model calculations suggest that the method is sufficiently reliable to calculate the thermal properties of nuclei over a reasonable temperature range.

We present phenomenological evidence that the strength of the Majorana term necessary to reproduce collective M 1-transition strength data could be significantly smaller than is conventionally assumed and therefore more in line with naive microscopic considerations. We also find that g-boson effects are important to the reproduction of the summed M1 strength.

Various shapes of Hg isotopes are calculated using a relativistic mean field theory. We observe shape transitions from oblate to prolate and prolate to oblate at A=178 and A=188, respectively. Both in the oblate and in the prolate solutions the sign of the hexadecupole moment changes from positive to negative values with increasing mass number. The predicted shape of the ground state agrees with the available data contrary to nonrelativistic calculations for neutron deficient isotopes. A low-lying superdeformed configuration is found in some isotopes, and found to be the ground state for ${}_{}{}^{180}{}_{}{}^{}\mathrm{Hg}$. A possible discrepancy between the experimental data of the quadrupole deformation and those of the charge radii is pointed out.

The non-Hermitian Hartree approximation and the variational principle with quasi-Hermitian operators are compared in two different boson models. In a very simple schematic model the two methods provide comparable results. For the non-Hermitian boson Hamiltonian obtained applying the Dyson boson expansion to a two-level pairing model the results obtained are different. The first approach, although it does not provide an upper bound for the ground state energy, is not limited by the appearance of spurious states that break the quasi-Hermiticity of the Hamiltonian.

Generator coordinate method calculations, including the case of two-generator coordinates, which is not usually considered in the relevant scientific literature, are performed for nuclear state energies, as well as momentum and density distributions of the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ nuclei. The construction potential used behaves like an harmonic oscillator at large distances from the center of the potential but it has also a strong short-range repulsion, which is expected to simulate, to some extent, effects of the inclusion of short-range correlations in the harmonic oscillator many-body wave function. The results are compared with available experimental information and discussed.

We describe an experimental study of the ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$${+}^{27}$Al reaction at 37.5 MeV/nucleon carried out with the AMPHORA multidetector. A small fraction of events in which the total charge was detected and which are shown to originate mainly from central collisions have been isolated and compared with statistical decay model predictions. Dynamical properties provide strong evidence for a radial directed collective component (blast wave) in the fragment energies which dominates the interfragment Coulomb repulsion and the thermal motion.