Abstract The decays of neutron-deficient 15 s 99Ag and 124 s 99gAg nuclides have been investigated at the Leuven Isotope Separator on-line facility. Sources were produced by the 92Mo(14N, 2p5n) and nat Zr ( 14 N , x n ) reactions. Positron, conversion electron, X- and γ-ray singles spectra together with γ-γ coincidence measurements have been performed on mass-separated samples. The 1 2 − isomeric level in 99)Ag decays with a 163.6 keV isomeric transition to a 7 2 + level at 342.6 keV. Of the 106 γ-rays observed in the β + EC decay of the 99Ag ground state, 68 γ-rays (92 % of the γ-ray intensity) have been placed in a proposed level scheme. The relative variation of the J π = 9 2 + and 1 2 − levels in odd-mass Ag isotopes has been calculated using a residual proton-neutron delta interaction. The occurrence of decoupled bands in the odd Pd isotopes is discussed. Detailed calculations for 99Pd have been carried out in the framework of the Nilsson model (strong-coupling wave functions) using a strong Coriolis band mixing. Energy spectra for high-spin states, wave functions and low-lying non-yrast levels (below Ex = 1 MeV) are also discussed.

We have studied the level structure of the even-odd $N=83$ nuclei $_{60}^{143}\mathrm{Nd}$, $_{62}^{145}\mathrm{Sm}$, $_{64}^{147}\mathrm{Gd}$, and $_{66}^{149}\mathrm{Dy}$. In order to explain the high level density above 2 MeV and low-lying high-spin states ($J>\frac{13}{2}$;${E}_{x}>2.5$ MeV), a Hamiltonian is constructed which in addition to the collective vibrations of the core, describes also the two quasiparticle excitations of the protons in the $Z=50\ensuremath{-}82$ shell. The results of the calculations are compared with the experimental data concerning the $N=83$ nuclei.NUCLEAR STRUCTURE $N=83$ nuclei Nd, Sm, Gd, Dy. Collective proton two quasiparticle degrees of freedom. High-spin states. Calculated levels $J$, $\ensuremath{\pi}$; $B(E3)$.

The level structure of 141Ce up to 3.7 MeV excitation energy has been investigated by the (d, t) and (3He, α) reactions using 17 MeV deuteron and 24 MeV 3He beams respectively. The angular distributions have been analyzed with standard DWBA calculations and spectroscopic factors are deduced. The experimental information is compared to unified model calculations involving both one-particle and two-particle one-hole configurations with quadrupole and octupole vibrations of the underlying N = 82 and N = 84 core.

Positive parity bands in 112, 114, 116, 118Sn have been excited up to levels with spin and parity Jπ = 12+ using Cd(α, 2nγ)Sn reactions. The experiments consisted of γ-ray excitation function, γ-γ coincidence, lifetime, γ-ray angular distribution, γ-ray linear polarization and conversion electron measurements. The observed bands show strong resemblances with ground-state bands of transitional nuclei in this mass region. It is pointed out that the Jπ = 0+ band-heads originate from 2p-2h excitations in the Z = 50 proton shell. The excitation energies of the band-heads are calculated by means of the macroscopic-microscopic renormalization method. Pair correlations between the 2h and 2p configurations are included separately in a phenomenological way by taking into account the pairing energies of the Cd and Te ground states with respect to the Sn ground state.

The original Skyrme force is extended by a momentum dependent three-body term. A study is made on its influence on nuclear matter properties and properties of finite nuclei. The problem of spin-instability is treated in two nuclear models. A force parametrization is proposed, giving good estimates for all nuclear matter quantities (binding energy per nucleon, incompressibility, reduced mass, isospin symmetric energy, etc.), as well as properties of finite nuclei throughout the whole mass region (ground-state energy, nucleon distributions, rms radii, single-particle removal energies, etc.). The proposed parametrization satisfies the spin stability conditions. The force is able to describe satisfactorily the ground-state properties, even fine effects of two nuclear mass regions, one belonging to the light mass region ($A=40\ensuremath{-}48$) and one belonging to the medium heavy mass region ($A=104\ensuremath{-}132$).NUCLEAR STRUCTURE Skyrme force extended with momentum dependent three-body term, spin stability conditions, application to Ca and Sn isotopes.

The extended Skyrme force has been used to calculate self-consistently ground-state properties, pairing correlations and properties of excited states of spherical nuclei throughout the whole mass region. The shell-model matrix elements exhibit the same behaviour as the bare reaction matrix elements of realistic interactions, and to be renormalized due to core polarization effects (3p-1h, 4p-2h), to generate good effective interactions. A numerical application on 42Ca is presented.

The extended Skyrme force has been used to calculate self-consistently ground-state properties, pairing correlations and properties of excited states of spherical nuclei throughout the whole mass region. The shell-model matrix elements exhibit the same behaviour as the bare reaction matrix elements of realistic interactions, and to be renormalized due to core polarization effects (3p-1h, 4p-2h), to generate good effective interactions. A numerical application on 42 Ca is presented.

Spectroscopic factors as well as parentage coefficients for collective Jiπ = 21+, 31− and 41+ states have been obtained for N = 29 nuclei and 59Ni via (τ, d p) reactions through isobaric analogue resonances (IAR). In the framework of a unified-model calculation, treating the one-neutron core-coupling (N = 29) and three-neutron core-coupling as well as pure three-neutron shell-model calculations (59Ni), a description can be given for most of the observed phenomena (energies, spectroscopic factors, parentage coefficients on the Jiπ = 21+, 31−, 41+ levels). Some discrepancies remain, especially with respect to the description of the splitting of the 2p12 neutron single-particle state. A comparison with earlier calculations for the N = 29 nuclei is carried out. With respect to 59Ni, the three-particle-cluster effects are pointed out and an extensive comparison between both types of calculation and with experiment is made.

$\ensuremath{\Delta}J=1$ bands built on low-lying $\frac{9}{{2}^{+}}$ states (307 keV in $^{119}\mathrm{I}$) have been observed in odd-$A$ $^{117.127}\mathrm{I}$ ($Z=53$) nuclei via ($^{6}\mathrm{Li}$, $3n\ensuremath{\gamma}$) reactions. Calculations of the total potential energy of these nuclear states in terms of a $[404]\frac{9}{{9}^{+}}$ Nilsson proton hole revealed minima at significant prolate deformations ($\ensuremath{\epsilon}=0.22$ for $^{119}\mathrm{I}$). The resulting excitation energies and band spacing calculations are in good agreement with experiment. The properties of these deformed $\frac{9}{{2}^{+}}$ states, which involve a $1{g}_{\frac{9}{2}}$ proton excited through the $Z=50$ major shell, are compared with those of the deformed $\frac{9}{{2}^{+}}$ states previously observed in odd-Sb ($Z=51$) nuclei.NUCLEAR REACTIONS $^{114\ensuremath{-}124}\mathrm{Sn}(^{6}\mathrm{Li}, 3n)$, ${E}_{\mathrm{Li}}=25\ensuremath{-}35$ MeV, measured $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences, $\ensuremath{\gamma}(E, \ensuremath{\theta}, t)$; deduced level scheme in odd-$A$ $^{117\ensuremath{-}127}\mathrm{I}$, $\ensuremath{\gamma}$ multipolarities, ${J}^{\ensuremath{\pi}}$. Enriched targets, Ge(Li) detectors.NUCLEAR STRUCTURE Odd-$A$ $^{117\ensuremath{-}127}\mathrm{I}$, calculated ${\frac{9}{2}}^{+}$ proton-hole state energies, $\ensuremath{\Delta}J=1$ rotational bands.

The g factor for the J/sup ..pi../+ isomeric level in /sup 134/Te can be reproduced within the experimental error by taking into account core polarization as well as velocity dependence corrections to the magnetic dipole operator. The wave function describing this isomeric state is obtained by diagonalizing a residual Gaussian interaction in a two-particle configuration space.

The $g$ factor for the ${J}^{\ensuremath{\pi}}={6}^{+}$ isomeric level in $^{134}\mathrm{Te}$ can be reproduced within the experimental error by taking into account core polarization as well as velocity dependence corrections to the magnetic dipole operator. The wave function describing this isomeric state is obtained by diagnolizing a residual Gaussian interaction in a two-particle configuration space.[NUCLEAR STRUCTURE $^{134}\mathrm{Te}$; calculated levels, $J$, $\ensuremath{\pi}$, $g$ factor for isomeric ${J}^{\ensuremath{\pi}}={6}^{+}$ level. Corrected $M1$ operator: core polarization, velocity dependence.]

We have described the positive parity rotational-like band structure Jπ = 12+, 32+, 52+ …, persisting in most odd-mass In nuclei (107 ≦ A ≦ 119), in both a deformed representation (Nilsson model) with extensive band-mixing calculations as well as in a spherical representation (particle-anharmonic-core coupling). Also, electromagnetic properties (static, dynamic) are described in both representations. The results from both types of calculation are compared extensively and possible numerical and analytic equivalences are pointed out (i.e. energy spectra, E2 transition rates and quadrupole moments, spectroscopic factors).

The inclusion of three-body forces to the effective nucleon-nucleon interaction has been frequently applied in nuclear self-consistent Hartree-Fock calculations. Thus, a dependence of the effective force on the nucleon density is exhibited, stimulating great interest in this manner. Antisymmetrized three-body matrix elements are evaluated, and applied with a zero-range three-body force within a finite basis of spherical single-particle states. The imposed antisymmetry ignores the existence of matrix elements of three identical nucleons. It provides for a better understanding of the structure of the three-body contribution to the Hartree-Fock ground state energy and for the exact relation between the three-body force and a density dependent two-body force. The discussion is given as well for spherical as for deformed nuclei. Problems concerning possible overbinding and violation of the spin stability by the zero-range three-body interaction are examined and represented in the angular momentum picture.NUCLEAR STRUCTURE antisymmetrized three-body matrix elements; HF ground state energy contribution; equivalence to density dependent two-body forces.

Abstract Microscopic nuclear structure information that can be reached by proton scattering through isobaric analogue resonances (IAR) is discussed, mainly within the framework of weak-coupling. The concept of isospin for unbound states is examined. A critical evaluation of the methods for extracting nuclear structure information from the experimental results (such as excitation functions, angular distributions, etc.) is given. The mass regions that are studied in detail are the Pb-region and the N = 82 neutron single-closed shell nuclei. Attention is given to the comparison between weak-coupling calculations and experimental results supporting this concept in many nuclei. Level schemes as well as proton partial decay widths and angular distributions have been calculated and compared with the existing data concerning the proton decay of IAR. The concept of generalized neutron particle-hole (GNPH) state is introduced and its occurence extensively discussed within the Pb-region and N = 82 nuclei.