In the framework of the resonating group method, the binding energy of the six-quark system with strangeness $s=-5$ is systematically investigated under the $\mathrm{SU}\mathrm{}\left(3\right)\mathrm{}$ chiral constituent quark model. The single ${\Xi }^{*}\Omega$ channel calculation with spins $S=0\mathrm{}$ and 3 and the coupled $\Xi \Omega$ and ${\Xi }^{*}\Omega$ channel calculation with spins $S=1\mathrm{}$ and 2 are considered, respectively. The results show the following observations. In the spin=0 case, ${\Xi }^{*}\Omega$ may be a bound dibaryon with the binding energy being $80.0\sim 92.4\hspace{0.5em}\mathrm{MeV}.$ In the $S=1\mathrm{}$ case, $\Xi \Omega$ may also be a bound dibaryon. Its binding energy ranges from 26.2 to 32.9 MeV. In the $S=2\mathrm{}$ and $S=3\mathrm{}$ cases, no evidence of bound dibaryons is found. The scattering lengths in the $S=0\mathrm{}$ and $S=1\mathrm{}$ cases are also given.

States in doubly odd ${}^{218}\mathrm{Fr}$ have been studied using in-beam spectroscopy $\alpha -\gamma -\gamma$ coincidence techniques mainly through the ${}^{209}\mathrm{Bi}{(}^{18}\mathrm{O},$ $2\alpha n)$ reaction at 94 MeV bombarding energy, using the $8\pi$ GASP-ISIS spectrometer at Legnaro. ${}^{218}\mathrm{Fr}$ shows a band structure, with interleaved states of alternating parities connected by enhanced $E1\mathrm{}$ transitions. Tentative spin assignment and the relation between the structure of ${}^{218}\mathrm{Fr}$ and its isotone ${}^{220}\mathrm{Ac}$ is discussed.

$g$ factors and lifetimes have been measured for the first $2^{+}$ and $4^{+}$ states of ${}^{46,48}\mathrm{Ti}$ and ${}^{50,52}\mathrm{Cr}$ employing the combined technique of projectile Coulomb excitation and transient magnetic fields. The same target was used in all measurements. The individual isotopes were provided by the ion source of the accelerator. These conditions guarantee high reliability and precision as demonstrated in earlier experiments. While the global behavior of the data is well explained by full $\mathrm{fp}$ shell model calculations, distinct deviations from theoretical predictions for ${}^{46,48}\mathrm{Ti}$ might be attributed to excitations of the ${}^{40}\mathrm{Ca}$ core.

The density of accessible levels at low spin in the ${(}^3\mathrm{He},\alpha \gamma )$ reaction has been extracted for the ${}^{161,162}\mathrm{Dy}$ and ${}^{171,172}\mathrm{Yb}$ nuclei. The entropy of the even-odd and even-even nuclei has been deduced as a function of excitation energy. The entropy of one quasiparticle outside an even-even core is found to be 1.70(15) $k_B.$ This quasiparticle picture of hot nuclei is well accounted for within a simple pairing model. The onset of two, four, and six quasiparticle excitations in the ${}^{162}\mathrm{Dy}$ and ${}^{172}\mathrm{Yb}$ nuclei is discussed and compared to theory. The number of quasiparticles excited per excitation energy is a measure for the ratio of the level energy spacing and the pairing strength.

An exact determination of the size of the pseudospin symmetry-violating part of the nucleon-nucleus scattering amplitude from scattering observables is presented. The approximation recently used by Ginocchio turns out to underestimate the violation of pseudospin symmetry. Nevertheless the conclusion of a modestly broken pseudospin symmetry in proton-${}^{208}\mathrm{Pb}$ scattering at $E_L=800\mathrm{}$ MeV remains valid.

We present proton and pion tranverse momentum spectra and rapidity distributions for Au+Au collisions at $10.8A\hspace{0.5em}\mathrm{GeV}/c.\mathrm{}$ The proton spectra exhibit collective transverse flow effects. Evidence of the influence of the Coulomb interaction from the fireball is found in the pion transverse momentum spectra. The data are compared with the predictions of the RQMD event generator.

We analyze a low-energy theorem of threshold pion electroproduction which allows one to determine the charge radius of the pion. We show that at the same order where the radius appears, pion loops induce a correction to the momentum dependence of the longitudinal dipole amplitude $L_{0+}^{\left(-\right)}.$ This model-independent correction amounts to an increase of the pion charge radius squared from the electroproduction data by about 0.27 ${\mathrm{fm}}^2.$ It sheds light on the apparent discrepancy between the recent determination of the pion radius from electroproduction data and the one based on pion-electron scattering.

The band structure of ${}^{219}\mathrm{Ra}$ has been studied via the ${}^{208}\mathrm{Pb}{(}^{14}\mathrm{C},3n)$ reaction using both $\gamma -\gamma$ and conversion electron-$\gamma$ coincidence measurements. This nucleus is at the lower mass limit of a region where static octupole deformation may occur. The conversion coefficients of seven transitions and two upper limits on conversion coefficients have been determined for the first time. The results establish the alternating parity nature of a sideband in this nucleus and also resolve an apparent conflict between radioactive decay data and heavy-ion reaction data. The resulting level scheme of ${}^{219}\mathrm{Ra}$ can be explained either by intermediate coupling of the odd neutron to a reflection symmetric core and a low frequency octupole vibrational mode or by strong coupling to a statically octupole deformed core.

The ${}^{11}\mathrm{B}(\overrightarrow{p},\gamma {)}^{12}\mathrm{C}$ reaction was studied by measuring the $\gamma$ rays that were produced when 80–100-keV polarized protons were stopped in a thick ${}^{11}\mathrm{B}$ target. Cross sections and vector analyzing powers at $90°$ were determined as a function of energy for capture to the ground and first excited states of ${}^{12}\mathrm{C}.$ These analyzing powers are particularly sensitive to the interference between s- and p-wave contributions, and to the relative phase between direct and resonance amplitudes. The results were used to produce a reliable extrapolation of the astrophysical S factor at 0 keV by means of a direct-capture-plus-resonances model calculation. The value of $S\left(0\right)\mathrm{}$ that was obtained for ${}^{11}\mathrm{B}(p,{\gamma }_0),$ $1.8\pm 0.4\hspace{0.5em}\mathrm{keV}\mathrm{}\mathrm{b},$ is in agreement with previously determined values, but for ${}^{11}\mathrm{B}(p,{\gamma }_1)$ the value of $S\left(0\right)\mathrm{}$ is $3.5\pm 0.6\hspace{0.5em}\mathrm{keV}\mathrm{}\mathrm{b}$ and is more than twice as large as previously determined values.

Upon application of both the general ensemble theory and basic thermodynamical principles, we derive in detail the thermodynamics of strange matter with density-dependent particle masses, which resolves the problem of inconsistencies in the thermodynamical properties of the earlier approaches. We then recalculate the properties of strange quark matter with this new thermodynamical treatment and our recently determined quark mass scaling, and find that the density behavior of the sound velocity is opposite to the previous finding, but consistent with one of our recent publications. The structure equations for strange stars are integrated with the presently obtained equation of state. We find that the mass-radius relation is similar to previous results except the maximum mass is smaller in our case if strange quark matter is absolutely stable.

The influence of the nuclear symmetry energy on the formation of a mixed quark-nucleon phase in neutron star cores is studied. We use simple parametrizations of the nuclear matter equation of state, and the bag model for the quark phase. The behavior of nucleon matter isobars, which is responsible for the existence of the mixed phase, is investigated. The role of the nuclear symmetry energy changes with the value of the bag constant B. For lower values of B the properties of the mixed phase do not depend strongly on the symmetry energy. For larger B we find that a critical pressure for the first quark droplets to form in the nucleon medium is strongly dependent on the nuclear symmetry energy, but the pressure at which last nucleons disappear is independent of it. We study the implications of these results for the structure of neutron stars. The finite-size effects are also considered. We find that the allowed range of surface tension for the mixed phase to be energetically favorable depends strongly on the nuclear symmetry energy.

The isospin dependence of light and heavy fragments emitted from excited nuclear systems and the change in isospin behavior between light and heavy fragments are studied in this report. The $〈N/Z〉$ is calculated using data reported in the literature and from the results of the simulation code SMM. A transition in the isospin behavior between light and heavy fragments may support the recently reported two-phase bifurcation of excited nuclear matter into a neutron-rich gas phase and a more symmetric liquid phase.

We calculate in (two-loop) chiral perturbation theory the local $\mathrm{NN}$ potentials generated by the three-pion exchange diagrams proportional to $g_A^4$ and $g_A^6.$ Surprisingly, we find that the total isoscalar central $3\pi$-exchange potential vanishes identically. The individually largest $3\pi$-exchange potentials are of isoscalar spin–spin, isovector central, and isoscalar tensor type. For these potentials simple analytical expressions can be given. The strength of these dominant $3\pi$-exchange potentials at $r=1.0\mathrm{}\mathrm{fm}$ is 3.9 MeV, 2.3 MeV, and 1.2 MeV, respectively. The T-matrix, mass-spectrum, and static potential generated by the crossed three-boson exchange diagrams with a scalar meson-nucleon coupling are derived in the appendix.

Fission-fragment mass distributions in the ${}^{232}\mathrm{Th}(\gamma ,f)$ reaction have been measured from the cumulative yields of radionuclides following activation at bremsstrahlung endpoint energies $E_e=7.5,$ 12.0, and 24.0 MeV. The yields of the light nuclei ${}^{24}\mathrm{Na}$ and ${}^{28}\mathrm{Mg}$ were detected following activation at $E_e=16.5\mathrm{}$ and 24.0 MeV. Energy dependences of the symmetric mode and light nuclide yields are discussed. Fine-structure manifestations near asymmetric and symmetric masses were observed.

The random phase approximation (RPA) is fully renormalized to take into account the ground-state correlations (g.s.c.) beyond the RPA, which arise due to the fermion structure of the collective RPA operators. As compared to the conventional renormalized RPA (RRPA), the novelty of the present extended renormalized RPA (ERRPA) is the inclusion of the particle-particle $\mathrm{}\left(\mathrm{pp}\right)\mathrm{}$ and hole-hole $\mathrm{}\left(\mathrm{hh}\right)\mathrm{}$ g.s.c. beyond the RPA along with the $\mathrm{ph}$ ones in the complete set of ERRPA equations. The formalism is illustrated by numerical calculations within a schematic four-level model. The results show that the effects of g.s.c. beyond the RPA due to $\mathrm{pp}$ (and $hh)$ transitions can cause a partial or complete compensation of the ones due to $\mathrm{ph}$ transitions. This reduces the deviation from the RPA energy-weighted sum of strength within the ERRPA as compared to the one within the conventional RRPA.

The $\Delta I=1\mathrm{}$ staggering (odd-even staggering) in octupole bands of light actinides is found to exhibit a “beat” behavior as a function of the angular momentum I, forcing us to revise the traditional belief that this staggering decreases gradually to zero and then remains at this zero value. Various algebraic models [spf-interacting boson model (spdf-IBM), vector boson model, nuclear vibron model] are shown to predict in their su(3) limits constant staggering for this case, being thus unable to describe the “beat” behavior. An explanation of the “beat” behavior is given in terms of two Dunham expansions [expansions in terms of powers of $I(I+1\mathrm{})\mathrm{}]$ with slightly different sets of coefficients for the ground-state band and the negative parity band, the difference in the values of the coefficients being attributed to Coriolis couplings to other negative parity bands. Similar “beat” patterns have already been seen in rotational bands of some diatomic molecules, like AgH.

A high-resolution study of dipole transitions to bound states up to 10 MeV in the $\mathrm{fp}$-shell nuclei ${}^{56}\mathrm{Fe}$ and ${}^{58}\mathrm{Ni}$ was performed by means of the nuclear resonance fluorescence method. Unpolarized and partially linearly polarized bremsstrahlung photons with different end point energies (6.5, 10, and 12 MeV) were used to determine excitation energies, spins, parities, and transition widths of more than 60 levels observed in each nucleus between 2 and 10 MeV. The vast majority of the observed transitions are dipole ones and to the strongest of them an $E1\mathrm{}$ assignment could be given. The $E1\mathrm{}$ strength distribution shows a high concentration around 8.2 MeV that may be connected with the $E1\mathrm{}$ pygmy resonance in heavier nuclei. The $M1\mathrm{}$ spin-flip strength shows a concentration around 8.7 MeV in ${}^{58}\mathrm{Ni}.$ On the contrary, in ${}^{56}\mathrm{Fe}$ its distribution is rather flat. The observed $M1\mathrm{}$ strength is weak in both nuclei. A study was made of the feeding and branching of the observed levels. Calculations were performed for these nuclei in the framework of the quasiparticle phonon model and a comparison with experimental results is made. Apart from the strength, experimental and calculated results agree quite well and information about a scissorslike mode in ${}^{56}\mathrm{Fe}$ and a $1^{-}$ two-phonon state in ${}^{58}\mathrm{Ni}$ could be extracted.

The nucleon pair shell model calculation is performed in terms of the SD collective pairs which are obtained in a suitable way to obtain the maximum collectivity. The method is applied to even-even Sn, Te, Xe, Ba, and Ce isotopes near the $A=130\mathrm{}$ region employing the (monopole and quadrupole) pairing plus quadrupole-quadrupole-type interaction with a very few parameters. The structure of energy levels for the quasi-γ band as well as the ground band is well reproduced in each nucleus. Other properties such as $E2\mathrm{}$ transition rates and binding energies also agree with experimental data very well. The overall fit with the experimental data is superior to the previous calculations.

The validity of the SD-pair truncation of the shell model is tested in a single j shell and in many j shells within the framework of the nucleon pair shell model. It is found that the SD-pair truncation is a good approximation of the shell model in the single-j case when the Hamiltonian consists of (monopole and quadrupole) pairing plus quadrupole-quadrupole-type interaction. The SD-pair truncation deteriorates if the quadrupole-quadrupole interaction is artificially large compared with the monopole pairing interaction. For multi-j shells, schematic calculations in the degenerate sd, pf, and sdg shells are performed for the extreme case of a pure quadrupole-quadrupole interaction. There is a large difference between the binding energies in the SD-pair-truncated subspace and those calculated in the full shell model space as in the case of a single-j shell. However, it is found that the basic properties of the band structure remain intact, and that the difference in energy levels, i.e., moments of inertia, can be easily absorbed by adjusting interaction strengths without changing the transition rates.