We propose a constrained molecular dynamics model for a fermionic system. In this approach the equations of motion of the centroids related to the single-particle phase-space distributions are solved by imposing that the one-body occupation probability $f_i,$ evaluated for each particle, can assume only values less than or equal to 1. This condition reflects the fermionic nature of the studied systems, and it is implemented with a fast algorithm which allows also the study of the heaviest colliding system. The parameters of the model have been chosen to reproduce the average binding energy and radii of nuclei in the mass region $A=30\mathrm{}–208.$ Some comparison to the data is given.

The Kadanoff-Baym (KB) equations are solved numerically for infinite nuclear matter. In particular we calculate correlation energies and correlation times. Approximating the Green’s functions in the KB collision kernel by the free Green’s functions the Levinson equation is obtained. This approximation is valid for weak interactions and/or low densities. It relates to the extended quasiclassical approximation for the spectral function. Comparing the Levinson, Born, and KB calculations allows for an estimate of higher order spectral corrections to the correlations. A decrease in binding energy is reported due to spectral correlations and off-shell parts in the reduced density matrix.

We study mutual dissociation of heavy nuclei in peripheral collisions at ultrarelativistic energies. Earlier this process was proposed for beam luminosity monitoring via simultaneous registration of forward and backward neutrons in zero degree calorimeters at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. Electromagnetic dissociation of heavy ions is considered in the framework of the Weizsäcker-Williams method and simulated by the RELDIS code. Photoneutron cross sections measured in different experiments and calculated by the GNASH code are used as input for the calculations of dissociation cross sections. The difference in results obtained with different inputs provides a realistic estimation for the systematic uncertainty of the luminosity monitoring method. Contributions to simultaneous neutron emission due to grazing nuclear interactions is calculated within the abrasion model. A good description of the CERN SPS experimental data on Au and Pb dissociation gives confidence in the predictive power of the model for AuAu and PbPb collisions at the RHIC and the Large Hadron Collider at CERN.

The high-spin structure of ${}^{203}\mathrm{Rn}$ has been investigated using two separate reactions. $\gamma -\gamma$ coincidences were measured for the ${}^{174}\mathrm{Yb}{(}^{34}\mathrm{S},5n)$ reaction at a beam energy of 167 MeV using the YRAST Ball array at the Wright Nuclear Structure Laboratory at Yale University. The ${}^{168}\mathrm{Er}{(}^{40}\mathrm{Ar},5n)$ reaction at an energy of 188 MeV was also employed. In this experiment γ rays were observed using the Gammasphere array in coincidence with the fragment mass analyzer at Argonne National Laboratory. The level scheme of ${}^{203}\mathrm{Rn}$ has been developed to spins of $\sim 41/2ħ$ and excitation energies of $\sim 3\hspace{0.5em}\mathrm{MeV}.$ The high-spin decay is dominated by three sequences of γ rays, and the possible configurations are discussed.

We perform a nonperturbative calculation of the $J/\Psi -\pi$ cross section using a $\mathrm{SU}\left(2\right)\mathrm{}\times \mathrm{SU}\left(2\right)\mathrm{}$ effective Lagrangian. Our results differ from those of previous calculations, especially in the description of vertices involving pions.

Properties of the possible $l-s$ closed shell nucleus ${}_{20}^{60}{\mathrm{Ca}}_{40},$ which is expected to be spherical in the ground state, are studied, using the self-consistent Hartree-Fock calculation plus the random-phase approximation with Skyrme interactions. The possible disappearance of the magic number $N=50\mathrm{}$ is suggested in nuclei near the neutron drip line. In particular, the low-lying octupole threshold strength, which may be strongly collective due to the disappearance of the $N=50\mathrm{}$ magic number, is pointed out.

Inelastic scattering data for the ${}^{6,7}\mathrm{Li}{+}^{138}\mathrm{Ba}$ and ${}^9\mathrm{Be}{+}^{64}\mathrm{Zn}$ systems, at near barrier energies, were measured. Coupled channel calculations were performed, between the elastic and inelastic channels, in order to investigate the competition between the breakup channel, the low-lying excitations, and transfer channels on the fusion cross section. From the analysis we conclude that the breakup of the ${}^6\mathrm{Li},$ with dissociation energy smaller than its first excited state, is responsible for the absence of the threshold anomaly, while the presence of the anomaly for the ${}^7\mathrm{Li}$ scattering is due to its strong inelastic coupling to the elastic channel. The behavior of ${}^9\mathrm{Be}$ is similar to that of ${}^6\mathrm{Li}.$

The spectral functions and light-cone momentum distributions of protons and neutrons in ${}^3\mathrm{He}$ and ${}^3\mathrm{H}$ are given in terms of the three-nucleon wave function for realistic nucleon-nucleon interactions. To reduce computational complexity, separable expansions are employed for the nucleon-nucleon potentials. The results for the light-cone momentum distributions suggest that they are not very sensitive to the details of the two-body interaction, as long as it has reasonable short-range repulsion. The unpolarized and polarized structure functions are examined for both ${}^3\mathrm{He}$ and ${}^3\mathrm{H}$ in order to test the usefulness of ${}^3\mathrm{He}$ as a neutron target. It is found that the measurement of the spin structure function of polarized ${}^3\mathrm{H}$ would provide a very clear test of the predicted change in the polarized parton distributions of a bound proton.

We have studied states of ${}^7\mathrm{He}$ using the ${}^9\mathrm{Be}{(}^{15}\mathrm{N}{,}^{17}\mathrm{F}{)}^7\mathrm{He}$ reaction at two incident energies, $E_{\mathrm{lab}}=240\mathrm{}$ MeV and 318.5 MeV and observed clearly the first excited state of ${}^7\mathrm{He}.$ An extended study of the three-body background was required to determine the excitation energy and width. The resonance parameters obtained for $l=1\mathrm{}$ are $E_x=2.95\mathrm{}\left(10\right)\mathrm{}$ MeV, and Γ=1.9(3) MeV. There is also evidence of a broad excited state at $E_x=5.8\mathrm{}\left(3\right)\mathrm{}$ MeV with Γ=4(1) MeV. From the analysis of the ${}^7\mathrm{He}$ ground state resonance, we extracted a value of 0.14(2) MeV for the width. In the calibration reaction ${}^{12}\mathrm{C}{(}^{15}\mathrm{N}{,}^{17}\mathrm{F}{)}^{10}\mathrm{Be}$ three high-lying states of ${}^{10}\mathrm{Be}$ are found at 13.6(1), 15.3(2), and 16.9(2) MeV.

High-spin states in the $N=Z$ nucleus ${}^{72}\mathrm{Kr}$ were populated using the ${}^{40}\mathrm{Ca}{(}^{36}\mathrm{Ar},2p2n)$ reaction at a beam energy of 145 MeV. The yrast band has been observed up to a tentative spin of 20ħ. Nonyrast rotational structures have also been observed for the first time. The alignment of $g_{9/2}$ protons and neutrons in the yrast band is observed to be significantly delayed relative to the heavier even-even Kr isotopes. Exact deformed cranked shell model calculations suggest that this could be due to the combined effect of isovector $\mathrm{}(T=1\mathrm{})\mathrm{}$ and isoscalar $\mathrm{}(T=0\mathrm{})\mathrm{}$ neutron-proton pairing correlations.

We present a microscopic variational model calculation to study the systematics of promising ββ decaying medium mass nuclei of ${}^{100}\mathrm{Mo},$ ${}^{104}\mathrm{Ru},$ ${}^{110}\mathrm{Pd},$ ${}^{114}\mathrm{Cd},$ ${}^{116}\mathrm{Cd},$ ${}^{124}\mathrm{Sn},$ ${}^{128}\mathrm{Te},$ and ${}^{130}\mathrm{Te}$ along with their daughters. The calculations have been attempted in the s-d-g-h shell using the pairing plus quadrupole-quadrupole $\mathrm{}(P+QQ)\mathrm{}$ interaction. This framework is found to be quite successful in describing the yrast $0^{+}$ and $2^{+}$ states of most of these nuclei when appropriate changes in the neutron-proton interaction component are taken into account. We also present 2ν ββ decay half-lives for ${}^{100}\mathrm{Mo}$ and ${}^{116}\mathrm{Cd}.$

The very-high-spin states of nuclei near $A=100\mathrm{}$ are investigated using the cranked Strutinsky method. Many very extended shape minima are found in this mass region, and their properties are tabulated.

A calculational scheme is developed to evaluate chiral corrections to properties of composite baryons with composite pions. The composite baryons and pions are bound states derived from a microscopic chiral quark model. The model is amenable to standard many-body techniques such as the BCS and random phase approximation formalisms. An effective chiral model involving only hadronic degrees of freedom is derived from the macroscopic quark model by projection onto hadron states. Chiral loops are calculated using the effective hadronic Hamiltonian. A simple microscopic confining interaction is used to illustrate the derivation of the pion-nucleon form factor and the calculation of pionic self-energy corrections to the nucleon and $\Delta \mathrm{}\left(1232\right)\mathrm{}$ masses.

The properties of nucleon-nucleon scattering inside dense nuclear matter are investigated. We use the relativistic Brueckner-Hartree-Fock model to determine on-shell and half off-shell in-medium transition amplitudes and cross sections. At finite densities the on-shell cross sections are generally suppressed. This reduction is, however, less pronounced than found in previous works. In case the outgoing momenta are allowed to be off energy shell the amplitudes show a strong variation with momentum. This description allows one to determine in-medium cross sections beyond the quasiparticle approximation, accounting thereby for the finite width which nucleons acquire in the dense nuclear medium. For reasonable choices of the in-medium nuclear spectral width, i.e., $\Gamma <~40\mathrm{MeV},$ the resulting total cross sections are, however, reduced by not more than about 25% compared to the on-shell values. Off-shell effects are generally more pronounced at large nuclear matter densities.

Velocity, angular, mass, and charge distributions of isotopically resolved residues coming from the reaction ${}^{32}\mathrm{S}{+}^{12}\mathrm{C}$ were measured at the bombarding energy ${E(}^{32}\mathrm{S})=19.5\mathrm{}\hspace{0.5em}\mathrm{M}\mathrm{e}\mathrm{V}/\mathrm{n}\mathrm{u}\mathrm{c}\mathrm{l}\mathrm{e}\mathrm{o}\mathrm{n}.$ Complete and incomplete fusion and direct components have been separated in the velocity spectra using kinematical analysis and deconvolution techniques. For each residue, incomplete and complete fusion cross sections have been extracted and the results are compared with the LILITA code predictions. The complete fusion cross section and the deduced critical angular momentum are also compared with other experimental data and with the predictions of theoretical models.

Experimental values of fusion energy thresholds, defined as energies at which the fusion cross section equals to the s-wave absorption cross section, are compared with barrier heights calculated assuming the adiabatic fusion potential with the nuclear part of the Woods-Saxon shape and parameters unambiguously determined by the liquid-drop-model contact force and the ground-state fusion Q value. Predictions of the “capture” cross sections in collisions of very heavy systems used to produce new superheavy elements are discussed.

Molybdenum extracted from geologically old zircons shows evidence for enhanced levels of ${}^{96}\mathrm{Mo},$ resulting from the double β decay of ${}^{96}\mathrm{Zr}.$ Evidence of nuclear fission in ${}^{95}\mathrm{Mo},$ ${}^{97}\mathrm{Mo},$ ${}^{98}\mathrm{Mo},$ and ${}^{100}\mathrm{Mo}$ extracted from the old zircons accompanies the double $\beta$ decay of ${}^{96}\mathrm{Zr},$ and is comparable in magnitude to the excess ${}^{96}\mathrm{Mo}.$ Zircons are excellent minerals for an experiment of this nature, since zircon U-Pb geochronology demonstrates that zircons have remained as closed isotopic systems over eons of time. The experimental data indicate that the half-life of ${}^{96}\mathrm{Zr}$ double $\beta$ decay is $(9.4\mathrm{}\pm 3.2)\times {10}^{18}$ yr and is in good agreement with the theoretically predicted half-life for the ${}^{96}\mathrm{Zr}$ decay to ${}^{96}\mathrm{Mo}$ occurring as a two neutrino decay.

We have studied $\eta$ production in the $p{d}^3\mathrm{He}\eta$ reaction from threshold to 1.5 GeV of incident proton energy. In our model, $\eta$ is produced from the decay of the resonance $N^{*}\mathrm{}\left(1535\right)\mathrm{}$ which is excited through the interaction of incoming proton and a nucleon in deuteron. In this model we are able to understand both the excitation function and the angular distribution of $\eta$ production quite well.

The phonon damping model is extended to describe the damping of charge-exchange resonances. The formalism is applied to calculate the strength distribution of the Gamow-Teller resonance in ${}^{90}\mathrm{Nb}.$ The results obtained are found to be in reasonable agreement with recent experimental data and with those of a previous study with explicit microscopic coupling to $2p2h$ configurations using a realistic interaction.