A new cluster decay process is proposed for the intermediate mass fragments (IMFs) observed in the low energy ${}^{58}\mathrm{Ni}{+}^{58}{\overrightarrow{\mathrm{Ni}}}^{116}{\mathrm{Ba}}^{*}$ reaction. The IMFs arise as multiple “clusters” of masses less than $\sim 20,$ having their origin in macroscopic liquid drop energy. The $\alpha$ nuclei, in particular ${}^{12}\mathrm{C}$ (or the complementary ${}^{104}\mathrm{Sn}),$ are predicted to be the most probable decays for this reaction. The multiple light particle $(Z<~2)$ emission, other than via the statistical evaporation process (not considered here), is also shown possible, but at higher energies. The calculations are shown to fit the available data on fragment production cross sections, with the total kinetic energy (TKE) of fragments taken as the parameter. The TKE is a measurable quantity, but at present no data on TKE exist for this reaction.

The effect of scattering with nonzero impact parameters between constituents in relativistic heavy-ion collisions is investigated. In solving the relativistic Boltzmann equation, the characteristic range of the collision kernel is varied from approximately 1.0 fm to zero while leaving the mean free path unchanged. Modifying this range is shown to significantly affect spectra and flow observables. The finite range is shown to provide effective viscosities, shear, bulk viscosity, and heat conductivity, with the viscous coefficients being proportional to the square of the interaction range.

We study the polarization change of ${\Lambda }^0’\mathrm{s}$ produced in ultrarelativistic heavy-ion collisions with respect to the polarization observed in proton-proton collisions as a signal for the formation of a quark-gluon plasma (QGP). Assuming that, when the density of participants in the collision is larger than the critical density for QGP formation, the ${\Lambda }^0$ production mechanism changes from recombination type processes to the coalescence of free valence quarks, we find that the ${\Lambda }^0$ polarization depends on the relative contribution of each process to the total number of ${\Lambda }^0’\mathrm{s}$ produced in the collision. To describe the polarization of ${\Lambda }^0’\mathrm{s}$ in nuclear collisions for densities below the critical density for the QGP formation, we use the DeGrand-Miettinen model corrected for the effects introduced by multiple scattering of the produced ${\Lambda }^0$ within the nuclear environment.

A specific linear combination of the total solar neutrino fluxes must equal the measured solar photon luminosity if nuclear fusion reactions among light elements are responsible for solar energy generation. This luminosity constraint, previously used in a limited form in testing the no neutrino oscillation hypothesis, is derived in a generality that includes all of the relevant solar neutrino fluxes and which is suitable for analyzing the results of many different solar neutrino experiments. With or without allowing for neutrino oscillations, the generalized luminosity constraint can be used in future analyses of solar neutrino data. Accurate numerical values for the linear coefficients are provided.

We compare a relativistic covariant model for proton-proton bremsstrahlung with high-quality data from KVI. The agreement in large parts of phase space is satisfactory. However, remarkably large discrepancies are observed for specific kinematic regions. These failures are shown to occur primarily when the final two-nucleon system has energies less than about 15 MeV.

The attenuation of the intraband intensity of a superdeformed band, which results from mixing with normally deformed configurations, is calculated using reaction theory. It is found that the sharp increase of the attenuation is mostly due to the tunneling through a spin dependent barrier and not to the chaotic nature of the normally deformed states.

A model based on chiral SU(3) symmetry in nonlinear realization is used for the investigation of nuclei, superheavy nuclei, hypernuclei, and metastable, exotic multistrange nuclear objects (so-called MEMOs). The model works very well in the case of nuclei and hypernuclei with one $\Lambda$ particle and rules out MEMOs. Basic observables that are known for nuclei and hypernuclei are reproduced satisfactorily. The model predicts $Z=120\mathrm{}$ and $N=172,$ 184, and 198 as the next shell closures in the region of superheavy nuclei. The calculations have been performed in self-consistent relativistic mean-field approximation assuming spherical symmetry. The parameters were adapted to known nuclei.

In-beam measurements of nanosecond lifetimes have been undertaken for some of the excited states in near-spherical nuclei ${}^{142,143}\mathrm{Pm}$ using the pulsed-beam γ coincidence technique and the generalized centroid-shift method of analysis. The ${}^{133}\mathrm{Cs}{(}^{13}\mathrm{C},xn)$ reaction with a 60 MeV pulsed beam of ${}^{13}\mathrm{C}$ was used to populate the excited states in the respective nuclei. The measured mean lifetimes have been compared with corresponding single-particle estimates.

High-spin states in ${}^{108}\mathrm{Cd}$ were populated in the reaction ${}^{64}\mathrm{Ni}{(}^{48}\mathrm{Ca},4n)$ at a beam energy of 207 MeV. Gamma-ray spectroscopy was performed with the Gammasphere spectrometer. A new excited band was found. The quadrupole moment measured using the method of residual fractional Doppler shifts has a value of $Q_0=8.5\mathrm{}e\mathrm{b},$ which corresponds to an axis ratio of $c/a=\mathrm{1.72.}\mathrm{}$

The coherent ${}^3\mathrm{He}{(e,e}^{\prime }{\pi }^{+}{)}^3\mathrm{H}$ reaction was measured at $Q^2=0.4\mathrm{}\hspace{0.5em}(\mathrm{GeV}{/c)}^2$ and $W=1.6\mathrm{}\hspace{0.5em}\mathrm{GeV}$ for two values of the virtual photon polarization, ε, allowing the separation of longitudinal and transverse cross sections. The results from the coherent process on ${}^3\mathrm{He}$ were compared to $\mathrm{H}{(e,e}^{\prime }{\pi }^{+})n$ data taken at the same kinematics. This marks the first direct comparison of these processes. At these kinematics ${(p}_{\pi }=1.1\mathrm{}\hspace{0.5em}\mathrm{GeV}/c),$ pion rescattering from the spectator nucleons in the ${}^3\mathrm{He}{(e,e}^{\prime }{\pi }^{+}{)}^3\mathrm{H}$ process is expected to be small, simplifying the comparison to ${\pi }^{+}$ production from the free proton.

In order to extract informations on pairing correlations in nuclei from experimental masses, the different contributions to odd-even mass differences are investigated within the Skyrme Hartree-Fock-Bogoliubov (HFB) method. In this part of the paper, the description of odd nuclei within HFB is discussed since it is the key point for the understanding of the above mentioned contributions. To go from an even nucleus to an odd one, the advantage of a two steps process is demonstrated and its physical content is discussed. New results concerning time-reversal symmetry breaking in odd nuclei are also reported.

The odd-even mass staggering in nuclei is analyzed in the context of self-consistent mean-field calculations, for spherical as well as for deformed nuclei. For these nuclei, the respective merits of the energy differences ${\Delta }^{\mathrm{}\left(3\right)\mathrm{}}$ and ${\Delta }^{\mathrm{}\left(5\right)\mathrm{}}$ to extract both the pairing gap and the time-reversal symmetry breaking effect at the same time are extensively discussed. The usual mass formula ${\Delta }^{\mathrm{}\left(3\right)\mathrm{}}$ is shown to contain additional mean-field contributions when realistic pairing is used in the calculation. A simple tool is proposed in order to remove the time-reversal symmetry breaking effects from ${\Delta }^{\mathrm{}\left(5\right)\mathrm{}}.$ Extended comparisons with the odd-even mass staggering obtained in the zero-pairing limit (schematic model and self-consistent calculations) show the nonperturbative contribution of pairing correlations on this observable.

We report here measurements of fusion cross-sections for the ${}^{16}\mathrm{O}{+}^{112,116}\mathrm{Sn}$ and ${}^{32}\mathrm{S}{+}^{112,116,120}\mathrm{Sn}$ systems. The set of systems studied with widely varying ground state Q values for the transfer of neutrons is a good case to understand the influence of single and multineutron transfer on the fusion process. The evaporation residue cross-sections were measured in small energy steps covering the region around the Coulomb barrier $(\approx {0.8V}_b$ to ${1.2V}_b).\mathrm{}$ The data have been analyzed in the framework of a coupled-channels formalism using the coupled-channels code CCFULL. A comparative study of the ${}^{16}\mathrm{O}{+}^A\mathrm{Sn}$ and ${}^{32}\mathrm{S}{+}^A\mathrm{Sn}$ systems suggests that the fusion process is predominantly influenced by coupling to collective excitations with coupling to multiphonon states (of target and projectile) becoming increasingly important for heavier systems. From the present analysis an unambiguous signature of the role of coupling to neutron transfer channels could not be inferred.

The relationship between the properties of nuclear matter and structure functions measured in lepton-nucleus deep inelastic scattering is investigated using light front dynamics. We find that relativistic mean field models such as the Walecka, Zimanyi-Moszkowski (and point-coupling versions of the same), and Rusnak-Furnstahl models contain essentially no binding effect, in accord with an earlier calculation by Birse. These models are found to obey the Hugenholtz–van Hove theorem, which is applicable if nucleons are the only degrees of freedom. Any model in which the entire Fock space wave function can be represented in terms of free nucleons must obey this theorem, which implies that all of the plus momentum is carried by nucleons, and therefore that there will be essentially no binding effect. The explicit presence of nuclear mesons allows one to obtain a modified form of the Hugenholtz–van Hove theorem, which is equivalent to the often-used momentum sum rule. These results argue in favor of a conclusion that the depletion of the deep inelastic structure function observed in the valence quark regime is due to some interesting effect involving dynamics beyond the conventional nucleon-meson treatment of nuclear physics.

Excited states in ${}^{164}\mathrm{Ta}$ were populated in the ${}^{142}\mathrm{Nd}{(}^{27}\mathrm{Al}{,5n)}^{164}\mathrm{Ta}$ reaction and investigated using the AFRODITE spectrometer array. The yrast rotational decay sequence up to spin ${21}^{-}$ is identified for the first time and assigned to the $\pi \left[514\right]{9/2}^{-}\otimes \nu \left[660\right]{1/2}^{+}$ configuration. A less intense, excited band is also identified. Low-spin signature inversion is observed in the yrast band, and is compared with the extended total Routhian surface calculations. It is likely that quadrupole pairing plays a role in generating the anomalous signature splitting, but an additional mechanism apart from the assumed mean field and quadrupole pairing interaction may be required to account for the experimental data.

Excited states in ${}^{180}\mathrm{Ta},$ populated in the ${}^{180}\mathrm{Hf}\mathrm{}(p,n)\mathrm{}$ and $\mathrm{}(d,2n)\mathrm{}$ reactions, were investigated by in-beam $\gamma$-ray and conversion-electron spectroscopy. In addition to the excited two-quasiparticle bands with $K^{\pi }{=0\mathrm{}}^{-}$ and $1^{-}$ known from previous work, we have identified six other low-lying two-quasiparticle bands with $K<~4.$ At intermediate K, 12 previously unkown levels were identified that could, however, not be associated reliably with rotational bands. These levels might be of significance in connection with the as yet unresolved problem of the stellar production mechanism for the $9^{-}$ isomer of ${}^{180}\mathrm{Ta}.$ At higher K we observe only levels known from the previous in-beam $\gamma$-spectroscopic studies with heavier projectiles, but suggest for some levels a different ordering into rotational bands based on band-mixing considerations. We also report a deuteron spectrum measured in the ${}^{181}\mathrm{Ta}{\mathrm{}(p,d)\mathrm{}}^{180}\mathrm{Ta}$ reaction with high resolution and statistics. This spectrum served for configuration assignments and yields an energy of $78\pm 1\hspace{0.5em}\mathrm{keV}$ for the $9^{-}$ isomer in ${}^{180}\mathrm{Ta}.$

The role of the Δ resonance has been discussed for the ${}^{12,13,14}\mathrm{C}(p,{\pi }^{-}{)}^{13,14,15}{\mathrm{O}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ reactions both experimentally and theoretically. Recent calculations suggested resonance effects in the energy dependence of the differential cross section that seem to contradict existing data. Since the available data points are limited, it is important to measure the energy dependence of the differential cross sections and the analyzing powers in order to better understand the still unclear reaction mechanism of the ground state $(p,{\pi }^{-})$ reactions. In the present paper, angular distributions of the differential cross sections and the analyzing powers were measured for ${}^{12,13}\mathrm{C}(p,{\pi }^{\pm })$ reactions at incident energies of 250, 300, and 350 MeV. Experimental results for the ${}^{12}\mathrm{C}(p,{\pi }^{-}{)}^{13}{\mathrm{O}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ reaction are compared with full-range distorted-wave Born approximation calculations.

A compilation of available data on proton-induced pion production is presented for the subthreshold region $E_{\mathrm{proton}}<~275\hspace{0.5em}\mathrm{MeV}.$ In this energy range the transition from coherent to quasifree pion production occurs and can be studied by observing the dependence on nuclear structure and proton beam energy. Large variations in the pion cross sections were found. Within a single data set the variations can be accounted for on the basis of energy (phase space) and isospin dependence. A scaling procedure was derived to relate the production probabilities of ${\pi }^{+},$ ${\pi }^0,$ and ${\pi }^{-}$ as functions of target mass and proton beam energy. A comparison of data sets obtained by different authors shows inconsistencies that appear to a certain extent to be of experimental origin.

Velocity and energy spectra of the light charged particles emitted in the ${}^{28}\mathrm{Si}{(E}_{\mathrm{lab}}=112\mathrm{}\hspace{0.5em}\mathrm{MeV}{)+}^{28}\mathrm{Si}$ reaction have been measured at the Strasbourg VIVITRON Tandem facility. The ICARE charged particle multidetector array was used to obtain exclusive spectra of the protons and $\alpha$ particles in the angular range $15°–150°$ and to determine the angular correlations of these particles with respect to the emission angles of the evaporation residues. The experimental data are analyzed in the framework of the statistical model. The exclusive energy spectra of $\alpha$ particles emitted from the ${}^{28}\mathrm{Si}{+}^{28}\mathrm{Si}$ compound system are generally well reproduced by Monte Carlo calculations using spin-dependent level densities. This spin dependence approach suggests the onset of large nuclear deformation at high spin. A reanalysis of previous $\alpha$-particle data from the ${}^{30}\mathrm{Si}{+}^{30}\mathrm{Si}$ compound system, using the same spin-dependent parametrization, is also presented in the framework of a general discussion of deformation effects in the $A_{\mathrm{CN}}\approx 60$ mass region.

Interaction cross sections for nuclei with $Z=2\mathrm{}–12$ on a ${}^{12}\mathrm{C}$ target are calculated in the Glauber model with matter densities obtained from Skyrme Hartree-Fock and relativistic Dirac potentials. The shell-model orbital occupations and separation energies are taken from configuration-mixing calculations and experimental spectroscopic data. Halo effects are present in the most neutron-rich C and N isotopes. The rms matter radii and interaction cross section exhibit a kink at $N=14\mathrm{}$ which can be associated with a change in the mean-field potential when the ${1s}_{1/2}$ orbit is being filled.