The Doppler shifts of γ rays following the decay of the $1_1^{\mathrm{-}}$ and $3_1^{\mathrm{-}}$ states in ${}_{}{}^{150,152,154}{}_{}{}^{}\mathrm{Sm}$ excited by inelastic scattering of 1.3 MeV neutrons from natural ${\mathrm{Sm}}_2$${\mathrm{O}}_3$ have been measured. With the Winterbon theory to describe the slowing down process of the recoiling atoms in the bulk of the target material, nuclear lifetimes could be extracted from these data. These measured lifetimes are compared to the results of a recent investigation with the gamma-ray induced Doppler (GRID) broadening technique and have been used to clarify problems associated with the incomplete knowledge of the feeding pattern in heavy nuclei inherent in the GRID method. The large E1 transition rates in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$ obtained in the previous study are confirmed; the B(E1) systematics has been extended to ${}_{}{}^{154}{}_{}{}^{}\mathrm{Sm}$ and is interpreted within the framework of the interacting boson model.

High-spin states of the N=49,50 nuclei ${}_{}{}^{85,86}{}_{}{}^{}\mathrm{Kr}$ have been investigated via the reactions ${}_{}{}^{82}{}_{}{}^{}\mathrm{Se}$${(}^7$Li,p3n) or ${}_{}{}^{82}{}_{}{}^{}\mathrm{Se}$${(}^7$Li,p2n), respectively, using 32 MeV ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ ions. In order to suppress γ rays arising from pure neutron evaporation the measurements of angular distributions and relative excitation functions of the γ rays as well as γγ coincidences have been performed in particle-γ coincidence modes. Additional information on excited states in ${}_{}{}^{85}{}_{}{}^{}\mathrm{Kr}$ has been obtained in connection with the ${}_{}{}^{82}{}_{}{}^{}\mathrm{Se}$(α,n) reaction at beam energies between 13 and 21 MeV. The level scheme of ${}_{}{}^{85}{}_{}{}^{}\mathrm{Kr}$ has been extended by a new sequence of high-spin states with excitation energies up to 4.8 MeV and tentative spins up to (23/2) that is built on top of the 17/$2^{+}$ μs isomer at 1991.8 keV. For ${}_{}{}^{86}{}_{}{}^{}\mathrm{Kr}$ a new level scheme of high-spin states with excitation energies up to 7.9 MeV and tentative spins up to (12) has been observed for the first time. The level sequences observed in ${}_{}{}^{85,86}{}_{}{}^{}\mathrm{Kr}$ are interpreted on the basis of shell-model calculations in the configuration space 1${\mathit{p}}_{3/2}$, 0${\mathit{f}}_{5/2}$, 1${\mathit{p}}_{1/2}$, and 0${\mathit{g}}_{9/2}$ for the protons and 0${\mathit{g}}_{9/2}$ or 0${\mathit{g}}_{9/2}$, 1${\mathit{d}}_{5/2}$ for the neutrons in ${}_{}{}^{85}{}_{}{}^{}\mathrm{Kr}$ or ${}_{}{}^{86}{}_{}{}^{}\mathrm{Kr}$, respectively. The inclusion of neutron-core excitations in the calculations for ${}_{}{}^{86}{}_{}{}^{}\mathrm{Kr}$ results in a remarkably improved agreement between experimental and calculated level energies. In this way considerable contributions of neutron-core excitations are strongly suggested for the positive-parity yrast states with spins 7ħ, 9ħ, and 10ħ.

High angular momentum states in ${}_{}{}^{79}{}_{}{}^{}\mathrm{Rb}$ were populated via the ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$${(}^{19}$F,2pn${)}^{79}$Rb and ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$${(}^{18}$O,4n${)}^{79}$Rb reactions. The 65 MeV ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ and 65 MeV ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ beams were provided by the Florida State University FN Tandem accelerator. Prompt γ-γ coincidences were measured for both reactions. Two additional γ cascades have been assigned to ${}_{}{}^{79}{}_{}{}^{}\mathrm{Rb}$, including a new high-excitation structure dominated by dipole transitions. Firm spin assignments were made for the first time for a number of states by means of directional correlation ratios and an angular distribution measurement using the ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$${(}^{19}$F,2pn) reaction. The Doppler-shift attenuation method was used to determine lifetimes for states and their respective side-feeding times in both the yrast positive-parity and yrast negative-parity states. Transition quadrupole moments were deduced from the transition strengths and compared with those predicted by Woods-Saxon cranking calculations. The energy spacings and mixing ratios were compared with particle-rotor calculations.

The time-dependent Green’s function method provides a basic theory for nuclear dynamics and heavy-ion collisions. The spectral function plays an important role in this theory containing information on correlations in the medium. These are usually neglected by using a quasiparticle approximation. In order to evaluate this particular approach it is important to establish in the static limit a link between this method and other traditional nuclear many-body theories such as the Brueckner approach. Using a self-consistent T-matrix approximation for the self-energy in the Green’s-function approach, treating particles and holes on equal footing, the self-energy can be obtained and compared with the Brueckner expression. In the quasiparticle limit it contains terms up to and analogous to the Brueckner second order rearrangement energy. In an extended quasiparticle approximation (EQP) which does not violate the sum rule for the spectral function the Brueckner third-order rearrangement energy can also be reproduced. The latter approximation constitutes a bridge between the Brueckner and Green’s-function methods. It assumes small absorption (and energy dependence) of the mean field. Some numerical estimates of the different approximation schemes that we discuss are shown. An iteration scheme for applying the EQP approximation is suggested.

The (β,γ) deformation parameters of even-even Xe, Ba, and Ce nuclei have been calculated by using the triaxial rotor model. Deformation parameters calculated, on one hand, from decay properties and, on the other hand, from energies are in good agreement. The smooth dependence of the deformation parameters on Z and N is discussed. The results are compared with those extracted from properties of odd-A nuclei.

A method for extracting effective p-n monopole matrix elements from experimental data is developed and applied to nuclei just below ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. Eight effective monopole matrix elements are extracted from a fit to 38 experimental data with an overall rms deviation of 116 keV. The resulting matrix elements are compared with those from semirealistic effective interactions.

The temperature dependence of different thermodynamic quantities such as the free energy, chemical potential, symmetry energy, single particle potential, equation of state, etc., is studied for asymmetric nuclear matter within a fully self-consistent model with an effective interaction. The equation of state is found to be quite soft in agreement with supernova calculations. The critical temperature for the occurrence of a liquid gas phase transition is found to decrease with the proton to neutron ratio γ and finally vanishes for pure neutron matter. The possibility of ${\mathrm{\pi }}^{\mathrm{-}}$ condensation has also been studied.

We present a fully self-consistent and relativistic calculation of the nucleon mean free path in nuclear matter and finite nuclei. Starting from the Bonn potential, the Dirac-Brueckner-Hartree-Fock results for nuclear matter are parametrized in terms of an effective σ-ω Lagrangian suitable for relativistic density-dependent Hartree-Fock (RDHF) approximation. The nucleon mean free path in nuclear matter is derived from this effective Lagrangian taking diagrams up to the fourth order into account. For nucleon mean free path in finite nuclei, we make use of the density determined by the RDHF calculation in the local density approximation. Our microscopic results are in good agreement with the empirical data and the predictions of the Dirac phenomenology.

We consider parity nonconservation effect for the Mossbauer transitions in ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{119}{}_{}{}^{}\mathrm{Sn}$ nuclei. To simplify the calculations we use contact approximation for nucleon-nucleon weak interaction. A corresponding parity nonconserving effective Hamiltonian is presented. The result of the calculation of γ-quantum circular polarization degree P∼3×${10}^{\mathrm{-}8}$ strongly contradicts the experimental value P∼${10}^{\mathrm{-}3}$. One may consider this huge disagreement as an indication of the unknown nuclear phenomena which leads to the enhancement of parity nonconservation. We stress the importance of a new independent measurement of the effect.

The isovector nuclear response of carbon is calculated using a random-phase approximation technique for both the non-spin-flip and the spin-flip channel. The calculated results are found to be in fair agreement with experimental results from C(${\mathrm{\pi }}^{\mathrm{-}}$,${\mathrm{\pi }}^0$) measurements at 500 and 400 MeV. The nuclear correlations quench and harden the charge-exchange quasifree peak as predicted.

We perform large-space shell-model calculations for the low-lying energy spectra of a few light nuceli${,}^4$He, ${}_{}{}^5{}_{}{}^{}\mathrm{He}$, ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, and ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, in a no-core model space with a realistic effective two-body interaction (Brueckner G matrix). Our G matrices are calculated for the Reid-soft-core potential in a harmonic-oscillator basis. Single-particle ‘‘-U’’ insertions are replaced by two-particle ‘‘-U’’ insertions and are included in the G-matrix calculations, which sum them to all orders. With the starting energy of the G matrix chosen to give approximately the experimental binding energy, we obtain nuclear energy spectra which are in reasonable agreement with experiment. We also investigate the dependence of our results on the size of the model space and on the harmonic-oscillator basis parameter (ħΩ).

Intermediate-mass fragments formed in reactions of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ ions with ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Ag}$ and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ targets have been studied at five energies between 0.48 and 3.6 GeV. Inclusive measurements show that as the bombarding energy increases, there is a strong enhancement in fragment cross sections and a trend toward isotropic angular distributions. Between 0.90 and 1.8 GeV, a change in the emission mechanism is suggested by (1) kinetic energy spectra with high-energy tails that become distinctly flatter, (2) a broadening of the spectral Coulomb peaks toward lower energies, and (3) charge distributions that become constant, exhibiting a power-law exponent τ≊2.0. Exclusive studies of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$${+}^{\mathrm{nat}}$Ag system at 0.90 and 3.6 GeV detected multifragment events with multiplicities up to four. The probability for high-multiplicity events increases about 40-fold between 0.90 and 3.6 GeV. At both energies, the kinetic energy spectra depend on multiplicity, especially when triggering on backward-emitted fragments. For multiplicity three events, a rapidity analysis of the data at 3.6 GeV is consistent with a single, relatively low source velocity, ${\mathit{v}}_{\mathit{S}}$≊0.4 cm/ns. The data are compared with predictions of a coplanarity-sphericity calculation, the sequential statistical decay code GEMINI, and a hybrid intranuclear cascade/percolation model.

Angular distributions of the double-differential cross section ${\mathit{d}}^2$σ/dΩ dE (σ) and the spin-flip probability ${\mathit{S}}_{\mathit{n}\mathit{n}}$ have been measured for inclusive inelastic proton scattering from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at ${\mathit{E}}_{\mathit{p}}$=318 MeV. Data have been obtained over an excitation energy range 9 MeV ≤${\mathit{E}}_{\mathit{x}}$≤42 MeV for laboratory scattering angles of 3°, 5°, 7°, 9°, 12°, 15°, and 18°. Multipole decompositions of angular distributions of both the spin-flip cross section ${\mathrm{\sigma }}_{\mathrm{SF}}$=σ${\mathit{S}}_{\mathit{n}\mathit{n}}$ and the estimated cross section for ΔS=0 transitions have been performed. The distribution of deduced ΔL=1, ΔS=0 (the giant-dipole resonance) strength peaks near ${\mathit{E}}_{\mathit{x}}$=22 MeV; although there is apparently much more strength relative to the energy-weighted sum rule (EWSR) than expected, this appears to be an artifact of instrumental background at small angles. Approximately 55% of the EWSR for ΔL=2, ΔS=0 was observed spread uniformly across the spectrum with no evidence for a giant-quadrupole resonance. Angular distributions for ${\mathrm{\sigma }}_{\mathrm{SF}}$ were analyzed using the predictions from random-phase approximation calculations for the nuclear structure and distorted-wave impulse approximation calculations for the scattering. These predictions are found to provide a good description of the ${\mathrm{\sigma }}_{\mathrm{SF}}$ data above ${\mathit{E}}_{\mathit{x}}$=25 MeV; values of ${\mathit{S}}_{\mathit{n}\mathit{n}}$ are predicted somewhat too low in this region.

The parity-nonconserving longitudinal asymmetry P has been measured in nonresonant regions in ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ for neutron energies in the range 6–86 eV. The measured value of ${\mathit{P}}_{\mathrm{nonres}}$=(9.8±21.7)×${10}^{\mathrm{-}6}$ is consistent with statistical descriptions of parity violation.

Neutron capture and transmission measurements have been made from 0.5 eV to 500 keV and have been analyzed to give parameters of resonances up to ∼100 keV. The average resonance spacing for s-wave resonances was determined to be 670±60 eV and the s-wave strength function (3.6±0.8)×${10}^{\mathrm{-}4}$. The average radiation width for s-wave resonances was 74±5 meV and that for p-wave resonances somewhat larger ∼89 meV. The Maxwellian average capture cross section at a stellar temperature of 30 keV was 92±6 mb. The capture resonance integral of 1.7±0.1 b calculated from the resonance parameters and the thermal cross section is smaller than the recently measured value of 2.38±0.17 b.

A collection of transition matrix elements from pion scattering to natural parity states of spin-zero nuclear targets has been generated from ${\mathrm{\pi }}^{+}$ and ${\mathrm{\pi }}^{\mathrm{-}}$ inelastic scattering, with results for proton, neutron, and isoscalar transitions, using a consistent reaction model and data from many sources. These are compared to electromagnetic results, to isoscalar results from folding analyses of alpha particle scattering, and to neutron matrix elements inferred by a variety of methods. Good agreement is generally found among these determinations. Comparison of neutron to proton matrix elements shows a simple proportionality to the neutron and proton numbers of the target, reflecting a simple bulk symmetry for a wide range of multipolarities, target masses, and transition strengths.

The elastic angular distributions for ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$${+}^{27}$Al have been measured at five energies from ${\mathit{E}}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$=48.8 to 69.5 MeV. The optical model analysis assumes both phenomenological and folding model potentials. Regions of sensitivity, where the potential is well determined, are found to be different for the real and the imaginary parts, and to vary with energy. The values of the real potential in the surface are weakly dependent on energy.

Differential cross sections for the elastic scattering of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ from ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ have been measured at 70, 80, 90, and 100 MeV bombarding energies. The data have been analyzed in the framework of the optical model, the parametrized phase shift model, the generalized Fresnel model, and the Coulomb-modified Glauber model. The scattering matrix elements, determined from the analysis of the data at each energy using these models, are in agreement with each other. The strong absorption radius over the range of energies for the measurement is energy independent. The total reaction cross section at these energies are deduced. The merits and demerits of various models in the context of the experimental data are discussed.

The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(n,p${)}^{12}$B reaction was studied using the white neutron source at the Los Alamos Meson Physics Facility/Weapon Neutron Research Center with a continuous incident neutron energy from 60 to 260 MeV. Double differential cross sections were measured in the angular range 11°≤${\mathrm{\theta }}_{\mathrm{lab}}$≤37°. Using the neutron time-of-flight facility at the Indiana University Cyclotron Facility, we also studied the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(p,n${)}^{12}$N reaction at ${\mathit{E}}_{\mathit{p}}$=186 MeV and the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(p→,n→${)}^{12}$N reaction at ${\mathit{E}}_{\mathit{p}\to }$=160 and 186 MeV. Double differential cross sections were measured between ${\mathrm{\theta }}_{\mathrm{lab}}$=0° and ${\mathrm{\theta }}_{\mathrm{lab}}$=50° in 5° steps. Spin observables ${\mathit{D}}_{\mathit{N}\mathit{N}}$, ${\mathit{A}}_{\mathit{Y}}$, and P were measured at ${\mathrm{\theta }}_{\mathrm{lab}}$=5°,9°,13° with ${\mathit{E}}_{\mathit{p}\to }$=160 MeV and ${\mathrm{\theta }}_{\mathrm{lab}}$=15°,20° with ${\mathit{E}}_{\mathit{p}\to }$=186 MeV. Angular distributions of differential cross section and spin observables for low-lying transitions in the residual nuclei are compared with disorted-wave impulse approximation (DWIA) calculations. A multipole decomposition analysis was performed to study the giant dipole and giant spin-dipole resonances. The contributions of the quasifree reaction in the giant resonance region was subtracted. The empirical results of energy distributions for dipole (ΔL=1) transition are compared with DWIA calculations using nuclear structure information obtained with a conventional shell model and also with a random phase approximation.

In this paper a quantum theoretical approach to single scalar and pseudoscalar meson production via mesonic Cherenkov mechanisms in homogeneous nuclear media is presented. The quantum mesonic Cherenkov coherence condition as well as the quantum rate of emission for Cherenkov mesons are derived. Some numerical estimates of these characteristic quantities as well as their semiclassical limits are discussed.