We have measured accurately the intensity ratio of L and K x rays in the ${}_{}{}^{157}{}_{}{}^{}\to _{}^{157}{}_{}{}^{}$Gd electron-capture decay as 0.932±0.015. From this ratio, we have deduced a value of 4.0±0.2 for the electron-capture ratio ${\mathit{P}}_{\mathit{L}}$/${\mathit{P}}_{\mathit{K}}$, leading, in turn, to a decay energy of 60.0±0.3 keV. This Q value is 2.9 keV lower than the currently accepted value. This decay energy rules out L capture to the daughter excited state at 54.54 keV; therefore, ${}_{}{}^{157}{}_{}{}^{}\mathrm{Tb}$ is not a suitable candidate for light-neutrino rest-mass studies based on this L-capture branch.

Cross sections for the formation of ${}_{}{}^{79}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{m}}{}_{}{}^{}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}_{}^{\mathit{m}}{}_{}{}^{}$, and ${}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}_{}^{\mathit{m}}{}_{}{}^{}$ nuclear states respectively through the reactions ${}_{}{}^{79}{}_{}{}^{}\mathrm{Br}$(n,n’${)}^{79}$${\mathrm{Br}}^{\mathit{m}}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$(n,n’${)}^{90}$${\mathrm{Zr}}^{\mathit{m}}$, and ${}_{}{}^{96}{}_{}{}^{}\mathrm{Ru}$(n,n’p${)}^{95}$${\mathrm{Tc}}^{\mathit{m}}$ induced at 14 MeV neutron energy are measured in the laboratory using ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$(n,α${)}^{24}$Na as the reference reaction. The measured cross-section values (40±3 mb for ${}_{}{}^{79}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{m}}{}_{}{}^{}$, 615±28 mb for ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}_{}^{\mathit{m}}{}_{}{}^{}$, and 135±8 mb for ${}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}_{}^{\mathit{m}}{}_{}{}^{}$) are in good agreement with the corresponding theoretical values (40 mb for ${}_{}{}^{79}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{m}}{}_{}{}^{}$, 584 mb for ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}_{}^{\mathit{m}}{}_{}{}^{}$, and 137 mb for ${}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}_{}^{\mathit{m}}{}_{}{}^{}$) estimated with compound nucleus theory and by assigning the isomer ratio in the limit 2 to 5 of the spin distribution factor. Probabilities for decay of excited nucleus to metastable and ground states via various possible spin states were calculated using a partial wave analysis method, an illustration of which is provided with an example of the reaction ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$(n,2n${)}^{114}$${\mathrm{In}}^{\mathit{m}}$. This method enables calculation of the isomer ratio even if the ground state of the nucleus is not radioactive.

A comparison is made of the recent ${\mathrm{\beta }}^{+}$-decay measurements of García et al. and the 1981 ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$(p,n${)}^{37}$Ar measurements of Rapaport et al. in order to see whether the experiments are consistent. García et al. were not able to determine the amount of Gamow-Teller strength in the isobaric analog state (IAS) or the Coulomb mixing of Fermi strength to a state near the IAS, and were forced to determine the amount of Gamow-Teller strength in the daughter 1371 keV state by making the branching ratios sum to unity. This approach leaves a range of possible values open for these quantities which we investigate. We find that the experiments could be consistent within a theoretically unlikely part of this range. We also examine the effect of this range of allowed values on solar and supernova neutrino cross sections of ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ and find weak dependence on the uncertainties described here. We discuss how the consistency of the two experiments can be tested more conclusively.

Pion double charge exchange on ${}_{}{}^{138}{}_{}{}^{}\mathrm{Na}$ (T=13), at a bombarding energy of 292 MeV, and a scattering angle of 5°, has been used to populate the double isobaric analog state in ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ce}$. The measurements provide determinations of Q value, width, and center-of-mass cross section. Results are compared with systematics and with the isobaric-multiplet-mass equation.

A detailed comparison between measured energy spectra and cross sections of ${}_{}{}^{1,2,3}{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, evaporated from the composite system ${}_{}{}^{96}{}_{}{}^{}\mathrm{Ru}$ (${\mathit{E}}^{\mathrm{*}}$≃113 MeV), and the predictions of the statistical model, has been carried out. Results obtained with transmission coefficients derived from optical model (OM), ingoing-wave boundary-condition model (IWBCM) and fusion systematics (FS) are presented. The best overall description of the data is obtained using IWBCM transmission coefficients, with reduced s-wave barriers, including, in the level density, deformations slightly larger than those predicted by the rotating liquid drop model (RLDM). ${}_{}{}^{2,3}{}_{}{}^{}\mathrm{H}$ yields are well reproduced by IWBCM transmission coefficients, while they are largely overestimated by the OM ones; the failure is found to be related to the imaginary part of the optical potential which accounts for the absorption of nonfusion reactions, in peripheral collisions. No combination of phase space and transmission coefficients is able to reproduce, simultaneously, the low emission barrier and the cross section observed for protons.

The ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$${(}^3$He,p${)}^{20}$F reaction has been studied at 18 MeV. Energy levels are measured up to ${\mathit{E}}_{\mathit{x}}$∼8.5 MeV and several new levels are observed. Angular distributions are measured for many of the levels and distorted wave Born approximation analyses are carried out. The L assignments are made and ${\mathit{J}}^{\mathrm{\pi }}$ limits are obtained.

An average resonance capture study of ${}_{}{}^{126}{}_{}{}^{}\mathrm{Te}$ was carried out with 2- and 24-keV neutron beams. The experiments provide a complete set of $0^{+}$, $1^{+}$, and $2^{+}$ levels and are in agreement with previous data. The completeness of these levels of ${}_{}{}^{126}{}_{}{}^{}\mathrm{Te}$, along with an earlier study of ${}_{}{}^{124}{}_{}{}^{}\mathrm{Te}$, permits a discussion of the structure of the Te isotopes in terms of U(5) and O(6) symmetries, and an investigation of the possible presence of intruder configurations.

The structure of low-lying states in heavy odd-mass N=82 isotones (147≤A≤153) is investigated in terms of a number-projected one- and three-quasiparticle Tamm-Dancoff approximation. A surface-delta interaction is taken as the residual nucleon-nucleon interaction. Excitation energies, spin, and parity are calculated and compared with the experimental data. Some predictions about dipole and quadrupole moments are presented.

We developed the MIT bag crystal model for nuclear matter in two aspects. First, we proved a Δμ=4 selection rule in the harmonic expansion of quark wave function by group theory. It enables us to push the maximum Dirac quantum number ${\mathrm{\kappa }}_{\mathit{m}}$ up from 7 to 15, therefore improving our calculation for the energy band and wave functions of quarks. Then, by a multipole expansion of the color fields we calculate the color interaction energy between quarks. These developments enable us to calculate the energy per nucleon in nuclear matter as done previously for a free nucleon. A nuclear equation of state is derived.

The liquid-drop model type expansion of the finite nuclear compressibility coefficients ${\mathit{K}}_{\mathit{A}}$ is studied in an energy density formalism, using a leptodermous expansion of the energies. It is found that the effective curvature compressibility coefficient ${\mathit{K}}_{\mathit{c}}$ is always negative for Skyrme type forces. It is also shown that the unexpectedly large value of about -800 MeV of the surface compressibility coefficient ${\mathit{K}}_{\mathit{s}}$ found by Sharma et al. is an artifact of their analysis procedure.

Microscopic structures of the low-lying nonrotational (intrinsic) states in the odd-odd nucleus ${}_{63}{}^{156}{}_{}{}^{}\mathrm{Eu}_{93}^{}{}_{}{}^{}$ are investigated using the quasiparticle-phonon nuclear model Hamiltonian including the pairing, quadrupole-quadrupole, octupole-octupole, and residual p-n interactions. The extent of vibrational admixtures to the two-quasiparticle configurations and the intrinsic matrix elements of electric octupole operator for the ‘‘same K opposite parity’’ bands are examined to conclude that, contrary to some recent suggestions, the low-energy ${}_{}{}^{156}{}_{}{}^{}\mathrm{Eu}$ spectrum does not contain ‘‘parity doublets’’ characteristic of reflection asymmetric shapes, in contrast with the structures seen in ${}_{}{}^{152}{}_{}{}^{}\mathrm{Eu}$ and ${}_{}{}^{154}{}_{}{}^{}\mathrm{Eu}$.

Employing a quadrupole-quadrupole interaction Hamiltonian in the so-called static path approximation, which is based on path integration in the space of single-particle potential fields, we have calculated the excitation energy, level density, and level density parameter of some of the zinc isotopes with neutron numbers, N=34, 40, 44, and 46 at finite temperatures, T≤2.0 MeV. Using a cranking Hamiltonian (with rotation about the X axis) in the same approach we have also studied the behavior of the moment of inertia as a function of rotational frequency (ω) and temperature for ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}$, taking it as an illustrative example. At low temperature (T≊0.5 MeV) the effect of rotation alignment is seen at ω≊1.0 MeV whereas at T≊2.0 MeV the moment of inertia becomes almost independent of ω, indicative of a rigid body behavior.

Energy spectra, B(E2) values, and ratios of the neutron-rich even-even Mo isotopes in the mass 100 region have been investigated in terms of the neutron-proton interacting boson model. Two different approaches were used. The first investigation is based on the validity of the Z=38 subshell closure considering ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}$ as a doubly magic core. In the second calculation Z=50 and N=50 were considered as valid closed shells leading to ${}_{}{}^{100}{}_{}{}^{}\mathrm{Sn}$ as a core. The results from both calculations are compared with experimental data.

Differences in the Hartree-Fock and effective shell-model interaction arising from alternative treatments of the kinetic-energy operator in finite nuclear many-body problems are described. The Hartree-Fock single-particle energies and their relationship to experimental removal energies depend sensitively on whether or not the center-of-mass kinetic energy is retained in the nuclear Hamiltonian. Large effects in particle-hole energies are obtained which have important consequences for effective shell-model Hamiltonians. If the center-of-mass contribution of the kinetic-energy operator is removed from the Hamiltonian, substantial effects appear in a simple example of the shell-model spectra of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ treated as four and five valence nucleons, respectively, outside a ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ core. The contributions to the energy coming from the valence, relative kinetic-energy operator push the energy spectra of both nuclei up by about 1 MeV relative to their ground states.

We investigate the electric multipole response of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ which could be tested in reactions with secondary beams at intermediate and high energies. We use simple arguments to show that, even in the most favorable cases, electric dipole excitations are by far more dominant. The contributions from higher order multipolarities will be less than the presently attainable experimental uncertainties.

The low-lying states (below the ${}_{}{}^3{}_{}{}^{}\mathrm{-}_{}^3{}_{}{}^{}$H threshold) of the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ nucleus are generated using three-body models with two-body nonlocal separable interactions between the constituent particles. The positions and widths of the states are determined by searching for the eigenvalues of the kernel of the Faddeev equations in the complex energy plane. When appropriate (for T=0 states only), the results are compared with a separate determination of these quantities from the α-d scattering process. All experimentally observed levels are found. Given that the Coulomb interaction is not included in our calculations, agreement with experiment is favorable for both the positions and the widths of the resonances.

Angular distributions of the ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$(p,α${)}^6$Li reaction leading to the ground and first two excited states of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ were measured at incident energies of 25.0 and 30.0 MeV. Both the one-step three- and five-nucleon transfers were considered in the theoretical analysis using current shell-model wave functions. We reproduce fairly well with distorted-wave Born approximation theory the experimental energy dependence of the integrated cross sections for the ground and first excited states of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$. A marked disagreement is observed for the second excited state, whose experimental integrated cross section shows a steeper energy dependence than the calculated one.

Evaporation residue cross sections for the ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$${+}^{58}$Ni and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{60}$Ni fusion reactions have been measured in the energy range from 3 below to 20 MeV above the Coulomb barrier. The low-energy fusion enhancements found in the two systems are very different. A comparative analysis suggests that collective pair transfer modes play an important role in the sub-barrier fusion of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$${+}^{58}$Ni.

Observations have been performed for electromagnetic transitions from the broad s-wave neutron resonances at 658 keV in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, at 180 keV in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, and at 103 keV in ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$. Capture gamma rays were measured with an anti-Compton NaI(Tl) detector, using a neutron time-of-flight technique. E1 and M1 transitions from those resonances to low-lying states with a strong single-particle character were found. The deduced partial radiative widths for E1 transition are in excellent agreement with the Lane-Mughabghab valence-capture model calculations taking the neutron effective charge, -Ze/A. Moreover, it is shown that essential features of the observed E1 and M1 transitions can be well explained by assuming a configuration-mixing wave function, ${\mathrm{\Psi }}_{\mathit{i}}$(1/$2^{+}$)=a($0^{+}$⊗1/$2^{+}$)+b($1^{+}$⊗1/$2^{+}$)+c($1^{+}$⊗3/$2^{+}$), for each resonance. The M1 transition strengths are compared also with more detailed shell model calculations in the model space of full (sd${)}^{\mathit{n}}$ configurations, using the Wildenthal effective interaction.

Proton elastic and inelastic cross sections have been measured at a number of energies between 3.73 and 7.74 MeV on targets of ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$. The (p,γ) cross section was measured at the same energies. Coupled-channel effects on the absorption cross sections are examined and an analysis in terms of dispersion theory is presented. A good representation of single particle energies was obtained. Calculations of two-particle–one-hole state densities agree qualitatively with the imaginary potential differences, in that shell effects disappear above the Coulomb barrier.