The level structures of odd $A\sim 110$ Ru, Pd, and Cd isotopes have been investigated following the fission of compound nuclei formed in heavy-ion fusion reactions. New sequences have been assigned to ${}^{107}\mathrm{Ru},$ and to ${}^{113,115,117,119}\mathrm{Cd}$ isotopes using the complementary fission fragment technique. A comparison with neighboring neutron-deficient and neutron-rich odd-A Ru, Pd, and Cd isotopes supports an interpretation of these sequences as originating from the neutron $h_{11/2}$ orbital. The occupation of this orbital polarizes the nucleus to a nonaxial shape in odd-A Ru, Pd and Cd isotopes over a wide range of neutron numbers. The yrast bands in the ${}^{114,116,118,120}\mathrm{Cd}$ cores have been extended to higher spins and excitation energies.

The asymptotic normalization coefficients (ANC’s) for the vertex ${}^{10}{\overrightarrow{\mathrm{B}}}^9\mathrm{Be}+p$ are deduced from a set of different proton transfer reactions at different energies. This set should ensure the peripheral character of the reaction and availability of the data for the elastic channels. The problems associated with the characteristics of the data and the analysis are discussed. For a subgroup of the set of available data, the uniqueness property of the extracted ANC’s is fulfilled. However, more measurements are needed before a definite conclusion can be drawn.

High-$p_T$ particle spectra in $p+p(\overline{p}+p),$ $p+A,$ and $A+B$ collisions are calculated in a parton model with QCD-inspired hard scattering and evolution in which intrinsic transverse momentum, its broadening due to initial multiple parton scattering, and jet quenching due to parton energy loss inside a dense medium are included phenomenologically. The intrinsic $k_T$ and its broadening in $p+A$ and $A+B$ collisions due to initial multiple parton scattering are found to be very important at low energies $(\sqrt{s}<50\mathrm{}$ GeV). Comparisons with S+S, S+Au, and Pb+Pb data with different centrality cuts show that the differential cross sections of large $p_T$ pion production ${(p}_T>1\mathrm{}\mathrm{GeV}/c)$ in $A+B$ collisions scale very well with the number of binary nucleon-nucleon collisions (modulo effects of multiple initial scattering). This suggests that hard parton scattering is the dominant particle production mechanism underlying the hadron spectra at $p_T\sim 2–10\mathrm{GeV}/c.\mathrm{}$ However, there is no evidence of jet quenching or parton energy loss. Assuming this model of parton scattering, nuclear broadening and parton energy loss, one can exclude an effective parton energy loss ${\mathrm{dE}}_q/dx>\mathrm{}0.01\mathrm{}$ GeV/fm and a mean free path ${\lambda }_q<7\mathrm{}$ fm from the experimental data of $A+B$ collisions at the SPS energies. Predictions for high $p_T$ particle spectra in $p+A$ and $A+A$ collisions with and without jet quenching at the RHIC energy are also given. Uncertainties due to initial multiple scattering and nuclear shadowing of parton distributions are also discussed.

The effect of baryon density on parton production processes of $\mathrm{gg}\rightleftharpoons \mathrm{ggg}$ and $\mathrm{gg}\rightleftharpoons q\overline{q}$ is studied using full phase space distribution function and also with inclusion of quantum statistics, i.e., Pauli blocking and Bose enhancement factors, in the case of both saturated and unsaturated quark gluon plasma. The rate for the process $\mathrm{gg}\rightleftharpoons q\overline{q}$ is found to be much less as compared to the most commonly used factorized result obtained on the basis of classical approximation. This discrepancy, which is found both at zero as well as at finite baryon densities, however, is not due to the lack of quantum statistics in the classical approximation, but is rather due to the use of Fermi-Dirac and Bose-Einstein distribution functions for partons instead of the Boltzmann distribution which is appropriate under such an approximation. Interestingly, the rates of parton production are found to be insensitive to the baryo-chemical potential particularly when the plasma is unsaturated although the process of chemical equilibration strongly depends on it. The thermal photon yields have been calculated specifically from unsaturated plasma at finite baryon density. The exact results obtained numerically are found to be in close agreement with the analytic expression derived using factorized distribution functions appropriate for unsaturated plasma. Further, it is shown that in the case of unsaturated plasma, the thermal photon production is enhanced with increasing baryon density both at fixed temperature and fixed energy density of the quark gluon plasma.

The question of pseudovector versus pseudoscalar coupling schemes for the kaon-hyperon-nucleon interaction is reexamined for the reaction $\gamma \overrightarrow{p}{K}^{+}\Lambda$ in several isobaric models. These models typically include Born terms, $K^{*}$ and $K_1$ exchanges in the t channel, and a few different combinations of spin-1/2 baryon resonances in the s and u channels. The coupling constants are obtained by fitting to a large data set. We find that both pseudoscalar and pseudovector couplings can allow for a satisfactory description of the present database. The resulting coupling constants, $g_{K\Lambda N}$ and $g_{K\Sigma N},$ in the pseudovector coupling scheme are smaller than those predicted using flavor SU(3) symmetry, but consistent with the values obtained in a QCD sum rule calculation.

The splitting of single-particle energies between spin-orbit partners in nuclei is examined in the framework of different self-consistent approaches, nonrelativistic as well as relativistic. Analytical expressions of spin-orbit potentials are given for various cases. Proton spin-orbit splittings are calculated along some isotopic chains (O, Ca, Sn) and they are compared with existing data. It is found that the isotopic dependence of the relativistic mean field predictions is similar to that of some Skyrme forces while the relativistic Hartree-Fock approach leads to a very different dependence due to the strong nonlocality.

High-spin states in doubly odd ${}^{172}\mathrm{Ta}$ were investigated in two different experiments by means of in-beam $\gamma$-ray and internal-conversion electron spectroscopy techniques. Excited states of ${}^{172}\mathrm{Ta}$ were populated using the ${}^{159}\mathrm{Tb}{(}^{18}\mathrm{O},5n)$ and ${}^{165}\mathrm{Ho}{(}^{12}\mathrm{C},5n)$ reactions at beam energies of 93 and 79 MeV, respectively. Eleven rotational bands, including twin bands in the normal deformation regime, have been observed and their configurations discussed. Three isomeric states have been found and their half-lives measured. Alignments, band crossing frequencies, and electromagnetic properties have been analyzed in the framework of the cranking model.

We present a fully quantum-mechanical, microscopic, unified treatment of ground-state band and multiphonon $\gamma$-vibrational bands using shell model diagonalization with the triaxial projected shell model. The results, which agree very well with data on the g- and $\gamma$-band spectra in ${}^{156-170}\mathrm{Er},$ as well as with recently measured $4^{+}$ two-phonon $\gamma$-bandhead energies in ${}^{166}\mathrm{Er}$ and ${}^{168}\mathrm{Er},$ are discussed in terms of the K mixing. Multiphonon $\gamma$-excitation energies are predicted.

The relaxation of the collective quadrupole motion in the initial stage of a central heavy ion collision at beam energies $E_{\mathrm{lab}}=5\mathrm{}$–20 $A\mathrm{MeV}$ is studied within a microscopic kinetic transport model. The damping rate is shown to be a nonmonotonic function of $E_{\mathrm{lab}}$ for a given pair of colliding nuclei. This fact is interpreted as a manifestation of the zero-to-first sound transition in a finite nuclear system.

Nuclear reactions induced by neutrons lead to the delayed emission of $\gamma$ rays contributing to the instrumental background in $\gamma$-ray astrophysics missions in space. The cross sections for the reactions ${}^{27}\mathrm{Al}{\mathrm{}(n,2p)\mathrm{}}^{26}\mathrm{Na},$ ${}^{27}\mathrm{Al}(n,\alpha {)}^{24}\mathrm{N}\mathrm{a},\mathrm{}$ and ${}^{56}\mathrm{Fe}{\mathrm{}(n,p)\mathrm{}}^{56}\mathrm{Mn}$ were measured up to a neutron energy of 50 or 65 MeV. A simple model was developed that allows one to extrapolate cross sections to higher energies. The magnitude of the instrumental background lines induced in the detectors of ESA’s future INTEGRAL mission is deduced from our measurements.

We introduce a combined macroscopic-microscopic transport approach employing relativistic hydrodynamics for the early, dense, deconfined stage of the reaction and a microscopic nonequilibrium model for the later hadronic stage where the equilibrium assumptions are not valid anymore. Within this approach we study the dynamics of hot, bulk QCD matter, which is expected to be created in ultrarelativistic heavy-ion collisions at the Super Proton Synchrotron, the Relativistic Heavy Ion Collider, and the Large Hadron Collider. Our approach is capable of self-consistently calculating the freeze-out of the hadronic system, while accounting for the collective flow on the hadronization hypersurface generated by the QGP expansion. In particular, we perform a detailed analysis of the reaction dynamics, hadronic freeze-out, and transverse flow.

A covariant, composite scalar diquark, Fadde’ev amplitude model for the nucleon is used to calculate pseudoscalar, isoscalar- and isovector-vector, axial-vector and scalar nucleon form factors. The last yields the nucleon $\sigma$ term and on-shell $\sigma$-nucleon coupling. The calculated form factors are soft, and the couplings are generally in good agreement with experiment and other determinations. Elements in the dressed-quark-axial-vector vertex that are not constrained by the Ward-Takahashi identity contribute $\sim 20\%$ to the magnitude of $g_A.$ The calculation of the nucleon $\sigma$ term elucidates the only unambiguous means of extrapolating meson-nucleon couplings off the meson mass shell.

Nuclide ${}^{237}\mathrm{Th}$ has been produced via multinucleon transfer reactions by 60 MeV/nucleon ${}^{18}\mathrm{O}$ ion irradiation of natural uranium. Thorium was radiochemically separated from the mixture of uranium and reaction products. The activity of thorium was measured by using a HPGe detector. The ${}^{237}\mathrm{Th}$ has been identified by measuring the growth and decay of the $\gamma$ rays from its daughter ${}^{237}\mathrm{Pa}.$ The half-life of ${}^{237}\mathrm{Th}$ was determined to be $4.69\pm 0.60$ min. Not only is the new value in agreement with the earlier one of $5.0\pm 0.9$ min obtained in our previous work, but also its experimental precision was improved.

We have studied the reaction $\eta \overrightarrow{d}\eta d$ close to threshold within a nonrelativistic three-body formalism. We considered several $\eta N$ and $\mathrm{NN}$ models, in particular potentials with separable form, fitted to the low-energy $\eta N$ and $\mathrm{NN}$ data to represent the two-body interactions. We found that with realistic two-body interactions a quasibound state does not exist in this system, although there is an enhancement of the cross section by one order of magnitude, in the region near threshold, which is a genuine three-body effect not predicted within the impulse approximation.

The unpolarized cross section for the electroproduction of the isoscalar $J^{\pi }{=3\mathrm{}}^{+}$ didelta dibaryon $d^{*}$ is calculated for a deuteron target using a simple picture of elastic electron-baryon scattering from the $\Delta \Delta {(}^7{D}_1)$ and the ${NN(}^3{S}_1)$ components of the deuteron. The calculated differential cross section at the electron laboratory energy of 1 GeV has a value of about 0.24 (0.05) nb/sr at the laboratory angle of $10°$ $\left(30\mathrm{}°\right)$ for the Bonn B potential when the dibaryon mass is taken to be 2.1 GeV. The cross section decreases rapidly with increasing dibaryon mass. A large calculated width of 40 MeV for $d^{*}\left(\Delta \Delta {}^7{S}_3\right)$ combined with a small experimental upper bound of 0.08 MeV for the $d^{*}$ decay width appears to have excluded any low-mass $d^{*}$ model containing a significant admixture of the $\Delta \Delta {(}^7{S}_3)$ configuration.

The basic theoretical formalism of angular momentum projection based on a particle-number-conserving treatment is elaborated. This method is, for the first time, applied to the middle of the fp shell. Full paired-configuration mixing calculations in the even-even deformed nuclei ${}^{46}\mathrm{Ti}$ and ${}^{48}\mathrm{Cr}$ show that only small parts $(\mathrm{weight}>0.01)$ of the configuration components are important for the case of either ground states or excited states. Low-lying excited energy spectra and reduced transition probabilities $B\left(E2\mathrm{}\right)\mathrm{}$ in the $K=0\mathrm{}$ bands can be reproduced well only by admixing very limited fully paired configurations. The improvements in the energy spectra are much more prominent than those without configuration mixing. The calculated $B\left(E2\mathrm{}\right)\mathrm{}$ values are more reasonable in comparison with the available experimental data, as well as those from other models.

High-spin states have been populated in ${}_{\hspace{0.5em}54}^{113}\mathrm{Xe}$ using the ${}^{58}\mathrm{Ni}{(}^{58}\mathrm{Ni},2pn)$ reaction. A backed-target experiment, at a low beam energy of 210 MeV, was performed using the JUROSPHERE spectrometer, while a thin-target experiment at 250 MeV was performed using the GAMMASPHERE spectrometer in conjunction with the MICROBALL charged-particle detector array and a neutron-detector array. Several new band structures have been identified, one of which exhibits characteristics of smooth termination at high spin.

Shell corrections of the finite deformed Woods-Saxon potential are calculated using the Green’s function method and the generalized Strutinsky smoothing procedure. They are compared with the results of the standard prescription which are affected by the spurious contribution from the unphysical particle gas. In the new method, the shell correction approaches the exact limit provided that the dimension of the single-particle (harmonic oscillator) basis is sufficiently large. For spherical potentials, the present method is faster than the exact one in which the contribution from the particle continuum states is explicitly calculated. For deformed potentials, the Green’s function method offers a practical and reliable way of calculating shell corrections for weakly bound nuclei.

We calculate the low-lying spectra of the zirconium isotopes $\mathrm{}(Z=40\mathrm{})\mathrm{}$ with neutron numbers from $N=52\mathrm{}$ to $N=60\mathrm{}$ using the ${1p}_{1/2}{0g}_{9/2}$ proton and ${2s1d0g}_{7/2}{0h}_{11/2}$ neutron subshells to define the model space. Effective proton-proton, neutron-neutron, and proton-neutron interactions have been derived using ${}^{88}\mathrm{Sr}$ as closed core and employing perturbative many-body techniques. The starting point is the nucleon-nucleon potential derived from modern meson exchange models. The comprehensive shell-model calculation performed in this work provides a qualitative reproduction of essential properties such as the subshell closures in ${}^{96}\mathrm{Zr}$ and ${}^{98}\mathrm{Zr}.$

The structure of superheavy elements claimed to have been discovered in the recent ${}^{208}\mathrm{Pb}{(}^{86}\mathrm{Kr},n)$ reaction at Berkeley is systematically studied in the relativistic mean field (RMF) approach. It is shown that various usually employed RMF forces, which give a fair description of normal stable nuclei, give different predictions for superheavy elements. Among the effective forces we tested, TM1 seems to be the best candidate to describe superheavy elements. The binding energies of the ${}^{293}118$ nucleus and its $\alpha$-decay daughter nuclei obtained using TM1 agree with those of FRDM within $2$ MeV. A similar conclusion, that TM1 is the best interaction, is also drawn from the calculated binding energies for Pb isotopes with the relativistic continuum Hartree-Bogoliubov (RCHB) theory. Using the pairing gaps obtained from the RCHB and taking into account the blocking effect for neutrons, RMF calculations with deformation are carried out for the structure of superheavy elements. The binding energy, shape, single particle levels, and the Q values of the $\alpha$-decay $Q_{\alpha }$ are discussed, and it is shown that the pairing correlation, blocking effect, and deformation are essential to properly understand the structure of superheavy elements. The $Q_{\alpha }$ values are calculated for the ground-state–to–ground-state transitions and for those respecting the angular momentum selection rule, and are compared with data.