We reevaluate some of the data presented recently by Hinnefeld et al. [Phys. Rev. C $58,$ 2563 (1998)] and use, in particular, a more accurate value for the ratio ${\Gamma }_{\gamma }/{\Gamma }_p$ of the partial widths of the 2750 keV level in ${}^{37}\mathrm{K}.$ Our analysis essentially confirms the conclusion drawn by these authors concerning the rapid depletion of ${}^{36}\mathrm{Ar}$ at explosive hydrogen-burning conditions.

SU(3) symmetry relations on the recently constructed hyperon-nucleon potentials are used to develop potential models for all possible baryon-baryon interaction channels. The main focus is on the interaction channels with total strangeness $S=-2,$ $-3,$ and $-4,$ for which no experimental data exist yet. The potential models for these channels are based on SU(3) extensions of potential models for the $S=0\mathrm{}$ and $S=-1$ sectors, which are fitted to experimental data. Although the SU(3) symmetry is not taken to be exact, the $S=0\mathrm{}$ and $S=-1$ sectors still provide the necessary constraints to fix all free parameters. The potentials for the $S=-2,$ $-3,$ and $-4$ sectors, therefore, do not contain any additional free parameters, which makes them among the first models of this kind. Various properties of the potentials are illustrated by giving results for scattering lengths, bound states, and total cross sections.

A complete version of the Moscow $\mathrm{NN}$ potential model is presented. The excellent description for all essential partial waves has been found in the energy range 0–350 MeV. The one-channel version of the model includes the orthogonality condition to most symmetric six-quark states in all lowest partial waves and thus, from this point of view, the model generalizes the well-known Saito’s orthogonality condition model for the baryon-baryon interaction case. The specific features of the presented model which distinguish it from many conventional force models are discussed in detail. One of them is a specific tensor mixing between nodal and nodeless wave functions which results in very reasonable values of the one-pion exchange cutoff parameter $\Lambda =0.78\mathrm{}\hspace{0.5em}\mathrm{GeV}$ and the $\pi \mathrm{NN}$-coupling constant value $f^2=0.075\mathrm{}$ in nice agreement with modern trends. The model, in case of its confirmation in precise few-nucleon calculations, can lead to noticeable revisions for many nuclear properties given by conventional force models.

For several modern nucleon-nucleon potentials state-of-the-art Faddeev calculations are carried out for the $\mathrm{nd}$ total cross section between 10 and 300 MeV projectile energy and compared to new high precision measurements. The agreement between theory and data is rather good, with an exception at higher energies where a 10% discrepancy builds up. In addition the convergence of the multiple scattering series incorporated in the Faddeev scheme is studied numerically with the result that rescattering corrections remain important. Based on this multiple scattering series the high energy limit of the total $\mathrm{nd}$ cross section is also investigated analytically. In contrast to the naive expectation that the total $\mathrm{nd}$ cross section is the sum of the $\mathrm{np}$ and $\mathrm{nn}$ total cross sections we find additional effects resulting from the rescattering processes, which have different signs and a different behavior as a function of the energy. A shadowing effect in the high energy limit only occurs for energies higher than 300 MeV. The expressions in the high energy limit have qualitatively a similar behavior as the exactly calculated expressions, but can be expected to be valid quantitatively only at much higher energies.

Low energy theorems have been derived for the coefficients of the effective range expansion in s-wave nucleon-nucleon scattering valid to leading nontrivial order in an expansion-based Q counting, a scheme in which both $m_{\pi }$ and $1/a$ (where a is the scattering length) are treated as small mass scales. Previous tests of these theorems based on coefficients extracted from scattering data indicate a pattern of gross violations which suggested serious problems for the perturbative treatment of pions implicit in Q counting. We discuss the possibility that uncertainties associated with extracting the coefficients from the scattering data make such tests invalid. Here we show that errors in the s-wave phase shift extractions are sufficiently small to test direct test predictions from Q counting at next to leading order. In particular we show that there exist low energy theorems for the sum of all terms in the effective range expansion beyond the first two which allow for precise tests. These low energy theorems fail badly which suggests that pionic aspects of Q counting are not under control.

For a set of realistic nucleon-nucleon potentials we evaluate microscopic parameters of binary collisions: time duration of the scattering state, mean distance, and rotation of nucleons during a collision. These parameters enter the kinetic equation as noninstantaneous and nonlocal corrections of the scattering integral, i.e., they can be experimentally tested. Being proportional to off-shell derivatives of the scattering T matrix, noninstantaneous and nonlocal corrections make it possible to compare the off-shell behavior of different potentials in a vicinity of the energy shell. The Bonn one-boson-exchange and Paris potentials are found to yield very close results, while the separable Paris potential differs.

$\beta$-decay half-lives of new neutron-rich isotopes ${}^{167}\mathrm{Tb}$ and ${}^{168}\mathrm{Tb}$ produced in the 20 MeV proton-induced fission of ${}^{238}\mathrm{U}$ have been determined to be 19.4(27) s and 8.2(13) s, respectively, using a gas-jet coupled on-line isotope separator. The present half-lives and those of the recently identified nuclei ${}^{159}\mathrm{Pm},$ ${}^{161}\mathrm{Sm},$ ${}^{165}\mathrm{Gd},$ ${}^{166}\mathrm{Tb}$ were compared with theoretical predictions. The recent calculation by the gross theory with the new one-particle strength functions shows quite good agreement with the experimental half-lives. Excited states of the daughter nuclides ${}^{167}\mathrm{Dy}$ and ${}^{168}\mathrm{Dy}$ have been established for the first time. Level energies of the first $2^{+}$ states in even-even Dy isotopes were found to show an irregular behavior at ${}^{164}\mathrm{Dy}$ and increasing deformation toward the neutron midshell around $N\approx 104$.

Prompt $\gamma$-ray cascades in neutron-rich nuclei around doubly magic ${}^{132}\mathrm{Sn}$ have been studied at Eurogam II using a ${}^{248}\mathrm{Cm}$ fission source. Here we report results for the four-valence-proton $N=82\mathrm{}$ nucleus ${}^{136}\mathrm{Xe}$ and for its $N=83\mathrm{}$ neighbor ${}^{137}\mathrm{Xe}.$ For both nuclei, the yrast level spectra have been considerably extended, and empirical nucleon-nucleon interactions have been used to assign probable shell model configurations. The ${}^{136}\mathrm{Xe}$ level energies are compared with those calculated using different sets of proton-proton interaction matrix elements, both diagonal and nondiagonal, obtained by fitting experimental data for other $N=82\mathrm{}$ isotones.

Yrast excitations in the $N=82\mathrm{}$ isotone ${}^{137}\mathrm{Cs}$ have been identified for the first time in thick-target $\gamma$-ray coincidence measurements for the system ${}^{232}\mathrm{Th}{+}^{136}\mathrm{Xe}$ using the Gammasphere array. The ${}^{137}\mathrm{Cs}$ nuclei were produced in deep inelastic one-proton-transfer reactions. By-products of the main investigation were two well-developed rotational bands which were identified in heavy reaction partner products complementary to ${}^{137}\mathrm{Cs}$ and are tentatively assigned to the little studied nucleus ${}^{231}\mathrm{Ac}.$ There was no difficulty in placing the 11 observed ${}^{137}\mathrm{Cs}$ transitions in a yrast level scheme extending to an $I^{\pi }{=(31/2\mathrm{}}^{-})$ level at 5494 keV. Interpretation was also straightforward, since the experimental level energies are in close agreement with results of shell model calculations performed earlier using empirical single particle energies and interaction matrix elements derived from experimental data for other $N=82\mathrm{}$ isotones.

The quadrupole moments of three decoupled bands in the odd-odd nuclei ${}^{130}\mathrm{Pr}$ and ${}^{132}\mathrm{Pr}$ were measured using the Doppler shift attenuation method in the bombardment of ${}^{105}$Pd with ${}^{35}$Cl at 173 MeV. The $\pi h_{11/2}\otimes \nu$${(f}_{7/2},$$h_{9/2})$ configuration was assigned to these structures on the basis of the observed in-band properties and relative deformations. New information is presented on the shape-driving behavior of the ${1/2}^{-}$[541] ${(f}_{7/2},$$h_{9/2})$ intruder neutron orbital, whose involvement in a particular configuration leads to quadrupole deformation values which are intermediate between those known for normally deformed and so-called superdeformed bands in this mass region.

The new plutonium isotope, ${}^{231}\mathrm{Pu},$ was produced by the ${}^{233}\mathrm{U}{(}^3\mathrm{He}{,5n)}^{231}\mathrm{Pu}$ reaction. After chemical separation, the ${}^{231}\mathrm{Pu}$ decay modes were studied using $\alpha$-spectrometry. The isotope, ${}^{231}\mathrm{Pu},$ was unequivocally identified by the $\alpha$-decay of the chain members from its $\alpha$- and electron-capture daughters using the $\alpha -\alpha$-correlation technique. The half-life of ${}^{231}\mathrm{Pu}$ was determined to be $(8.6\mathrm{}\pm 0.5)$ min. An $\alpha$-group with an energy of $(6.72\mathrm{}\pm 0.03)$ MeV was assigned to ${}^{231}\mathrm{Pu}.$

Isospin is included in the description of the Coulomb excitation of multiple giant isovector dipole resonances. In the excitation of even-even nuclei, a relevant portion of the excitation strength is shown to be associated with $1^{+}$ two-phonon states, which tends to be hindered or completely suppressed in calculations in which the isospin degree of freedom is not considered. We find that the excitation cross section is strongly dependent on the ground state isospin.

We consider the propagation and damping of isovector excitations in heated nuclear matter within the Landau Fermi-liquid theory. Results obtained for nuclear matter are applied to calculate the giant dipole resonance (GDR) at finite temperature in heavy spherical nuclei within a Steinwedel and Jensen picture. The centroid energy of the GDR slightly decreases with increasing temperature and the width increases as $T^2$ for temperatures $T<\mathrm{}4\mathrm{}\hspace{0.5em}\mathrm{MeV}$ in agreement with recent experimental data for GDR in ${}^{208}\mathrm{Pb}$ and ${}^{120}\mathrm{Sn}.$ The validity of the method for other Fermi fluids is finally suggested.

We have studied the effects of pairing correlations on the excitation energy ${(E}^{*})$ dependence of the total nuclear level density, parity-projected level density, and spin cutoff factor for two heavy systems ${}^{152}\mathrm{Sm}$ and ${}^{160}\mathrm{Yb},$ within a microscopic approach based on static path approximation to a grand canonical partition function. For both systems considered, we find that pairing has significant effects on the $E^{*}$ dependence of total level densities. At moderate excitation energies ${(E}^{*}\sim 10\hspace{0.5em}\mathrm{MeV})$ it supresses the total level density nearly by two orders of magnitude. By fitting the total level density to a Bethe-type formula with energy backshift $\left({\Delta }_{\mathrm{BS}}\right),$ we find that ${\Delta }_{\mathrm{BS}}\approx 2.5\hspace{0.5em}\mathrm{MeV}$ for the excitation energy beyond $15\hspace{0.5em}\mathrm{MeV}.$ At lower excitation energies, however, ${\Delta }_{\mathrm{BS}}$ is strongly $E^{*}$ dependent. We find that the effects of pairing on the spin cutoff factor and the parity-projected level densities (or parity asymmetry) is somewhat less important. We also compare our results for the spin cutoff factor with the ones conventionally employed in statistical model codes.

We have studied dipole states of oxygen isotopes in large scale shell model calculations. The calculated photoreaction cross sections in ${}^{16}\mathrm{O}$ and ${}^{18}\mathrm{O}$ give reasonable agreement with experimental observations both in the low energy region below $ħ\omega =15\mathrm{}\mathrm{MeV}$ and in the high energy giant resonance region $(15\mathrm{}\mathrm{MeV}<\mathrm{}\mathrm{ħ}\mathrm{\omega }<~30\mathrm{}\mathrm{MeV}).\mathrm{}$ We found that the transition strength below giant dipole resonance $(ħ\omega <~15\mathrm{MeV})$ exhausts about 10% of the classical Thomas-Reiche-Kuhn sum rule value in heavier oxygen isotopes than ${}^{18}\mathrm{O}.$ The $T_{>}$ GDR (giant dipole resonance) appears in ${}^{18}\mathrm{O}$ and ${}^{20}\mathrm{O}$ having comparable transition strengths with the $T_{<}$ GDR, while $T_{>}$ strengths become much smaller than $T_{<}$ ones in ${}^{22}\mathrm{O}$ and ${}^{24}\mathrm{O}.$

In this work, we investigate the properties of superdeformed identical bands in the $A\sim 150$ mass region by microscopic calculations based on the new SLy4 parametrization of the Skyrme force and on a density-dependent zero-range pairing interaction. Many experimental properties are correctly reproduced, with however some qualitative differences in the description of identical bands.

A microscopic approach is proposed to the damping of the double giant dipole resonance (DGDR). The double-time Green’s function method is used to derive a closed set of coupled equations for the propagation of two-phonon excitation through the field of incoherent nucleon pairs. The analytical expressions for the width and energy shift of the DGDR are obtained. The numerical calculations are performed for ${}^{90}\mathrm{Zr},$ ${}^{90}\mathrm{Sn},$ and ${}^{208}\mathrm{Pb}$ for several characteristics of the DGDR at zero as well as nonzero temperatures T. The results are found in reasonable agreement with existing experimental systematics for the width and energy of the DGDR. As compared to the estimation within the harmonic picture, the anharmonicity leads to a noticeable enhancement of the integrated photoabsorption cross section (IPACS) over the DGDR region. The DGDR width is found to increase sharply with increasing T at $T<~3\mathrm{MeV},$ but goes to a saturation at $T>\mathrm{}3\mathrm{}\mathrm{MeV}$. The harmonic limit for the DGDR width is restored already at $T>~1.5\mathrm{MeV}.$ It is shown that the IPACS of the DGDR can also be enhanced compared to its harmonic value if it is built on a hot GDR.

We study the important effects of Fermi surface distortion on the isoscalar giant monopole resonance (ISGMR), within a Fermi-liquid drop model, by considering consistently the effects on nuclear incompressibility coefficients and the boundary conditions needed to determine the energy of the ISGMR. There is a significant difference between the static nuclear incompressibility K, derived as a stiffness coefficient with respect to an adiabatic change in the bulk density, and the dynamic one $K^{\prime }$ associated with the zero sound velocity. We show that the enhancement in the energy of the ISGMR, the lowest breathing mode, which is due to the renormalization of K into $K^{\prime }$ is strongly suppressed by the effects of the Fermi surface distortion on the boundary condition. This is not the case for higher breathing modes such as the overtone. We also discuss, in particular, the effects of the Fermi surface distortion on energy weighted sums for the monopole mode and on the constrained and the scaling incompressibility coefficients and their relation to the liquid drop one.