For particular $\Delta$-production angles, an unambiguous determination of the $N\overrightarrow{N}\Delta N$ transition amplitudes is performed, from $N\overrightarrow{N}\left(N\pi \right)N$ experiments, in which the polarization states are measured in the entrance channel only. A three-step method is developed, which determines, first, the magnitudes of the amplitudes, second, independent relative phases, and third, some dependent relative phases for resolving the remaining discrete ambiguities. A rule of ambiguity elimination is applied, which is based on the closure of a chain of consecutive independent relative phases, by means of the ad hoc dependent one. A generalization of this rule is given for the case of a nondiagonal matrix connecting observables and bilinear combinations of amplitudes.

The reaction ${\Xi }^{-}\overrightarrow{d}n\Lambda \Lambda$ is studied within the framework of the Faddeev equations as a possible tool to gain insight into the final state $\Lambda \Lambda$ interaction. The neutron differential energy spectrum gives a final state interaction that is sensitive to both the $\Lambda \Lambda$ amplitude at threshold and the coupling between the $\Lambda \Lambda$ and $\Xi N$ channels. The latter is a result of interference between two mechanisms for the production of the final state, which suggests that this reaction could give a measure of flavor $\mathrm{SU}\left(3\right)$ violation in the two-baryon system.

Polarization phenomena are studied for the reaction ${d+}^3\mathrm{He}\to {p+}^4\mathrm{He}$ (for $E_d<~1$ MeV) using a formalism of partial amplitudes. The nuclei are considered as elementary particles with definite values of spin and $P$ parity. A general parametrization of the matrix element in terms of a limited number of partial amplitudes (for ${d+}^3$He interaction in $s$ and $p$ states) is given and the expressions for all polarization observables are derived for the $s$ interaction. Relations between different polarization observables are derived and the conditions for maximizing the differential cross section of the process $\overrightarrow{d}{+}^3\overrightarrow{H}\mathrm{e}\to {p+}^4\mathrm{He}$ are indicated. The spin structure of the matrix elements of the processes ${d+}^3\mathrm{He}\to {d+}^3\mathrm{He}$, ${d+}^3\mathrm{He}\to {n+p+}^3\mathrm{He}$, ${d+}^3\mathrm{He}\to {p+p+}^3\mathrm{H}$, and ${d+}^3\mathrm{He}\to d+d+p$ is established in the near-threshold region.

Lifetimes of excited states of ${}^{115}\mathrm{Sb}$ were measured by the Doppler shift attenuation method in the $(\alpha ,2n\gamma )$ reaction at $E_{\alpha }$ = 27.2 MeV. The experimental level scheme and the electromagnetic transition probabilities have been interpreted in terms of the interacting boson-fermion model. A reasonable agreement with the experiment was obtained for the positive-parity states. The experimental data also show the applicability of the cluster-vibrational model for the mixing of two ${9/2}^{+}$ states having different intrinsic configurations.

The sum rule strength of the high energy octupole resonance (HEOR) and the transition rates of low-lying $2^{+}$ and $3^{-}$ states of ${}^{116}\mathrm{Sn},$ excited by 240 MeV α scattering, have been determined from deformed potential and folding model analyses. Deformed potential cross sections for both the low-lying $3^{-}$ state and the HEOR are greater than folding cross sections by a factor of 1.18. The high energy octupole resonance was found to exhaust $(70\mathrm{}\pm 15)\%$ and $(83\mathrm{}\pm 15)\%$ of the $E3\mathrm{}$ energy-weighted sum rule from the two analyses, respectively. The data for the low-lying states are fit well by the calculations made with both models using electromagnetic values for the transition rates. Optical-model parameters were obtained from fits to elastic scattering data. The differential cross sections for the elastic scattering and inelastic scattering exciting the low-lying $2^{+}$ and $3^{-}$ states in ${}^{116}\mathrm{Sn}$ were measured over the angle range from ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=1.6\mathrm{}°$ to 35.2°.

Excited states of the nucleus ${}^{87}$Y were investigated via the reaction ${}^{80}\mathrm{Se}{(}^{11}\mathrm{B},4n)$ at 45 MeV. γ rays were detected with the six-detector array OSIRIS CUBE. The level scheme of ${}^{87}$Y has been extended up to $J^{\pi }{=33/2\mathrm{}}^{\left(-\right)}$ at $E$≈7 MeV. Mean lifetimes of eight levels have been deduced using the Doppler-shift-attenuation method. The structure of ${}^{87}$Y has been interpreted in terms of the shell model. The calculations performed in the model space $\pi {(0f}_{5/2}{,1p}_{3/2}{,1p}_{1/2}{,0g}_{9/2}\left)\nu {(1p}_{1/2}{,0g}_{9/2}\right)$ well reproduce experimental excitation energies and transition strengths in ${}^{87}$Y, especially the large $B\left(M1\mathrm{}\right)\mathrm{}$ values of up to 1.8 W.u. between yrast states with $J>\mathrm{}21/2\mathrm{}$. Structural differences between ${}^{87}$Y and the isotone ${}^{85}$Rb are discussed on the basis of the shell-model calculations.

The high-spin level structures of ${}^{94,95}\mathrm{Mo}$ $\mathrm{}(N=52,53\mathrm{})\mathrm{}$ have been investigated via the ${}^{65}\mathrm{Cu}{(}^{36}\mathrm{S}$, $\alpha {p2n)}^{94}\mathrm{Mo}$ and ${}^{65}\mathrm{Cu}{(}^{36}\mathrm{S}$, $\alpha {pn)}^{95}\mathrm{Mo}$ reactions at 142 MeV. The level schemes have been extended up to spin $J\approx 19ħ$ and excitation energies $E_x\approx$12 MeV. Spherical shell-model calculations have been performed and compared with the experimental energy levels. The level structure of ${}^{94}\mathrm{Mo}$ exhibits a single-particle nature and the higher-angular-momentum states are dominated by the excitation of a $g_{9/2}$ neutron across the $N=50\mathrm{}$ shell gap. The level sequences observed in ${}^{95}\mathrm{Mo}$ have been interpreted on the basis of the spherical shell model and weak coupling of a $d_{5/2}$ or a $g_{7/2}$ neutron to the ${}^{94}\mathrm{Mo}$ core.

High-spin states in the even-even nucleus ${}^{74}\mathrm{Se}$ were investigated via the ${}^{65}\mathrm{Cu}{(}^{12}\mathrm{C},{p2n)}^{74}\mathrm{Se}$ reaction at a beam energy of 50 MeV. On the basis of coincidence data three of the known bands were extended to higher spins and two new bands were found. Experimental crossing frequencies were deduced for various band structures and compared with cranked-shell-model results. Previous assignments of $g_{9/2}$ quasiproton and $g_{9/2}$ quasineutron alignments along the yrast line were confirmed when a near-prolate shape is assumed. Hartree-Fock-Bogoliubov calculations predict a deformed shape for excited states in ${}^{74}\mathrm{Se}$ which shows, however, a considerable softness in triaxiality. For the first time in the mass 70 region, band structures and quasiparticle alignments in ${}^{74}\mathrm{Se}$ were also investigated using the projected shell model. The calculations support the previous conclusions for the positive-parity states and predict that the lowest negative-parity bands are signature partners based on $g_{9/2}$ quasiproton excitations, with a $g_{9/2}$ quasineutron crossing at higher frequencies leading to a four-quasiparticle configuration at high spins.

Rotational bands in ${}^{170}\mathrm{Yb}$ and ${}^{171}\mathrm{Yb}$ have been studied with the reactions ${}^{170}\mathrm{Er}(\alpha {,xn)}^{174-x}\mathrm{Yb}$ at 35 and 40 MeV. Considerable extensions have been made to the previously published level schemes, and new structures have been found in each nucleus. Angular correlation measurements and reduced transition probability $\left[B\right(M1:\overrightarrow{I}I-1)/B(E2:\overrightarrow{I}I-2\left)\right]$ ratios have been extracted. Detailed comparisons are made with the first major projected shell model calculations for excited bands in an odd-$N$ nucleus ${}^{171}\mathrm{Yb}$.

High-spin states of ${}^{157}\mathrm{Tb}$ were populated via the reactions ${}^{154}\mathrm{Sm}{(}^7\mathrm{Li},4n)$ at 35 MeV and ${}^{150}\mathrm{Nd}{(}^{11}\mathrm{B},4n)$ at 55 MeV. Previously known bands have been extended and one new structure has been identified. The rotational alignment behavior of the bands and band crossing systematics have been analyzed. Experimental $B\left(M1\mathrm{}\right)/B\left(E2\mathrm{}\right)\mathrm{}$ ratios for the strongly coupled bands have been extracted and compared with theoretical predictions. New results were also obtained for the $N=92\mathrm{}$ isotone ${}^{155}\mathrm{Eu}$. The [411]3/2 and [413]5/2 pseudo-spin partner bands were observed in both nuclei. Experimental $B\left(E1\mathrm{}\right)/B\left(E2\mathrm{}\right)\mathrm{}$ ratios have been determined in both ${}^{155}\mathrm{Eu}$ and ${}^{157}\mathrm{Tb}$. However, the estimated large $B\left(E1\mathrm{}\right)\mathrm{}$ strengths can be explained without static octupole deformation. The [411]3/2 bands in ${}^{155}\mathrm{Eu}$ and ${}^{157}\mathrm{Tb}$ have been found identical up to spin $I=\frac{23}{2}$, which might be explained by changes in deformation.

Thirteen targets with mass numbers from 58 to 238 were irradiated with the antiproton beam from the Low Energy Antiproton Ring facility at CERN leading to the formation of antiprotonic atoms of these heavy elements. The antiproton capture at the end of an atomic cascade results in the production of more or less excited residual nuclei. The targets were selected with the criterion that both reaction products with one nucleon less than the proton and neutron number of the target be radioactive. The yield of these radioactive products after stopped-antiproton annihilation was determined using gamma-ray spectroscopy techniques. This yield is related to the proton and neutron density in the target nucleus at a radial distance corresponding to the antiproton annihilation site. The experimental data clearly indicate the existence of a neutron-rich nuclear periphery, a “neutron halo,” strongly correlated with the target neutron separation energy $B_n$ and observed for targets with $B_n<$10 MeV. For two-target nuclei ${}^{106}\mathrm{Cd}$ and ${}^{144}\mathrm{Sm}$, with larger neutron binding energies, a proton-rich nuclear periphery was observed. Most of the experimental data are in reasonable agreement with calculations based on current antiproton-nucleus and pion-nucleus interaction potentials and on nuclear densities deduced with the help of the Hartree-Fock-Bogoliubov approach. This approach was, however, unable to account for the ${}^{106}\mathrm{Cd}$ and ${}^{144}\mathrm{Sm}$ results.

The $\beta$ decay of ${}^{97}\mathrm{Sr}$ to ${}^{97}\mathrm{Y}$ has been investigated using ion-guide on-line mass separation and a 10 Ge-detector array to record $\gamma -\gamma$ coincidences to a detection limit well below that of former studies. Similarities are found in the $\beta$-decay patterns of ${}^{99}\mathrm{Zr}$ and of its isotone ${}^{97}\mathrm{Sr}$ and also in the $\gamma$-ray decay rates and branchings of the corresponding levels in their respective daughters ${}^{99}\mathrm{Nb}$ and ${}^{97}\mathrm{Y}$. This indicates a persisting influence of the $d_{5/2}$ neutron shell closure for ${}^{99}\mathrm{Nb}$. The level structure of ${}^{99}\mathrm{Nb}$ and the $\beta$-feeding pattern are discussed in the frame of the interacting boson-fermion plus broken pair model and the microscopic quasiparticle phonon model.

High-spin states in the even ${}^{116}\mathrm{Xe}$ and ${}^{118}\mathrm{Xe}$ isotopes have been studied with the ${}^{58}\mathrm{Ni}{(}^{64}\mathrm{Zn})$ reaction at 265 MeV using the GAMMASPHERE array. Several new rotational bands have been identified in these nuclei, and previously observed bands have been extended. In ${}^{116}\mathrm{Xe}$, a strongly coupled $(\Delta I=1)$ rotational band attributed to the $\nu \left[h_{11/2}{(g}_{7/2}{,d}_{5/2}{)}^1\right]$ configuration and a decoupled $(\Delta I=2)$ rotational band identified with the $\pi \left[h_{11/2}{g}_{7/2}\right]$ configuration have been found. Experimental observations also suggest that another rotational band may be understood within the framework of smooth band termination. In ${}^{118}\mathrm{Xe}$, two well-developed sidebands have been observed to decay by multiple paths to the yrast band at spins near $14ħ$ and $28ħ$. Identification of the higher-lying sideband has resulted in a substantial revision to the previously proposed spin extent of the yrast band, thereby resolving an earlier disgreement with theoretical calculations.

Particle number fluctuations in the quasiparticle random-phase approximation (QRPA) and the renormalized quasiparticle random-phase approximation are investigated. A closed expression for the ground state wave function is used, which allows an exact evaluation of the ground state phonon number and correlation function, being valid to any order in the backward amplitudes. In realistic calculations a sudden increase in the particle number fluctuations is found in both approximations when the particle-particle interaction approaches the value at which the QRPA collapses. This behavior is strongly correlated with the ground state quasiparticle content and can be understood as a signature of the phase transition previously found in simpler exactly solvable models.

We present a discussion of the equation of state of cold nuclear matter predicted by our recently completed Thomas-Fermi model. The equation is in the form of a three-term polynomial in the cube root of the density, with coefficients that are functions of the relative neutron excess δ. The coefficients are tabulated in the range from $\delta =0\mathrm{}$ (standard nuclear matter) to $\delta =1\mathrm{}$ (neutron matter), making it very easy to calculate, for a given $\delta$, the pressure, compressibility, saturation binding, and any other property of the Thomas-Fermi equation of state. We discuss the empirical information concerning abnormal densities and large neutron excess that is contained in the measured values of the surface energy, surface diffuseness, and the neutron skin.

A generalized description of the $0_2^{+}$ state in collective even-$A$ nuclei is obtained in the $Q$-excitation scheme. It is shown that for the whole symmetry triangle the two-$Q$ and three-$Q$ configurations are exhausted in a sum more than 90% of the norm of the $0_2^{+}$ state. For the parameter range important for the description of nuclear data it is about 95% of the norm. The results obtained are applied to the description of the $E2\mathrm{}$-decay branching ratio of the $0_2^{+}$ state in nondeformed nuclei.

It is shown that the complex admittance, which describes the dissipation of the giant dipole resonance (GDR) in hot nuclei, can be derived from the microscopic double-time Green function for the propagation of the GDR. The damping width of the GDR is calculated directly from the complex admittance without explicitly solving the equation for the poles of the Green function. Using this method, a systematic study of the width of the GDR as a function of temperature $T$ is carried out in ${}^{120}$Sn and ${}^{208}$Pb. The quantal width, caused by the coupling to $\mathrm{ph}$ configurations decreases slowly with increasing $T$. The thermal width, caused by the coupling to $\mathrm{pp}$ and $\mathrm{hh}$ configurations at $T\ne 0$, increases sharply at low temperatures up to $T\sim$ 3 MeV, and slowly at high temperatures, where it reaches a saturation in the region of $T>\mathrm{}$ 3–4 MeV. The calculated values of the total damping width of the GDR are found in reasonable agreement with the experimental data in heavy-ion fusion reactions and inelastic $\alpha$ scattering. The mechanism of the “disappearance” of the GDR at high temperatures is analyzed. The evidence of motional narrowing in the hot GDR is investigated.

A self-consistent particle-phonon coupling model is used to investigate the properties of the isobaric analog resonance in ${}^{208}$Bi. It is shown that quantitative agreement with experimental data for the energy and the width can be obtained if the effects of isospin-breaking nuclear forces are included, in addition to Coulomb force effects. A connection between microscopic model predictions and doorway state approaches, which make use of the isovector monopole resonance, is established via a phenomenological ansatz for the optical potential.

The Holstein-Primakoff boson mapping technique is applied to transform Hamiltonians defined in terms of the generators of the SU(2) and Sp(4) groups. These solvable models consist of a pair of fermions which interact with hard bosons. It is shown that the mapping to ideal bosons preserves the algebra and that exact matrix elements of the original fermionic Hamiltonian can be reconstructed from the bosonic representation.

The consistency of the renormalized random-phase approximation (RRPA), to treat correlations nearby a phase transition, is analyzed. The results of the RRPA and its quasiparticle version (RQRPA) for monopole and quadrupole particle-hole excitations and pairing vibrational modes, are compared with exact results and with results of the conventional quasiparticle random-phase approximation (QRPA). The calculations are performed in schematic models.