The properties of the pseudo spin-orbit potential, in particular those related to its singularity structure, are investigated in the relativistic Hartree formalism. The validity of sufficient conditions for the pseudospin symmetry are also analyzed. We have found a strong influence of the scalar meson mass and the compressibility modulus on the single-particle energy level ordering of the pseudospin doublet.

We develop a complete Dirac-Hartree-Fock-Bogoliubov approximation to the ground state wave function and energy of finite nuclei. We apply it to spin-zero proton-proton and neutron-neutron pairing within the Dirac-Hartree-Bogoliubov approximation (we neglect the Fock term), using a zero-range approximation to the relativistic pairing tensor. We study the effects of the pairing on the properties of the even-even nuclei of the isotopic chains of Ca, Ni, and Sn (spherical) and Kr and Sr (deformed), as well as the $N=28\mathrm{}$ isotonic chain, and compare our results with experimental data and with other recent calculations.

We present the framework for the ab initio no-core nuclear shell model and apply it to obtain properties of ${}^{12}\mathrm{C}.$ We derive two-body effective interactions microscopically for specific model spaces from the realistic CD-Bonn and the Argonne V8’ nucleon-nucleon $\mathrm{}\left(\mathrm{NN}\right)\mathrm{}$ potentials. We then evaluate binding energies, excitation spectra, radii, and electromagnetic transitions in the $0ħ\Omega ,$ $2ħ\Omega ,$ and $4ħ\Omega$ model spaces for the positive-parity states and the $1ħ\Omega ,$ $3ħ\Omega ,$ and $5ħ\Omega$ model spaces for the negative-parity states. Dependence on the model-space size, on the harmonic-oscillator frequency, and on the type of the $\mathrm{NN}$ potential, used for the effective interaction derivation, are studied. In addition, electromagnetic and weak neutral elastic charge form factors are calculated in the impulse approximation. Sensitivity of the form-factor ratios to the strangeness one-body form-factor parameters and to the influence of isospin-symmetry violation is evaluated and discussed. Agreement between theory and experiment is favorable for many observables, while others require yet larger model spaces and/or three-body forces. The limitations of the present results are easily understood by virtue of the trends established and previous phenomenological results.

Angular distributions of tritons from the ${}^{123}\mathrm{Sb}{\mathrm{}(p,t)\mathrm{}}^{121}\mathrm{Sb}$ reaction induced by 26 MeV protons have been measured up to an excitation energy of about 3 MeV using a Q3D spectrometer. Many previously unknown levels of ${}^{121}\mathrm{Sb}$ have been observed. Microscopic calculations of the ${}^{123}\mathrm{Sb}{\mathrm{}(p,t)\mathrm{}}^{121}\mathrm{Sb}$ reaction cross sections, using the quasiparticle-phonon model, give a reasonably good description of the fragmentation of the (p,t) cross sections and the lack of (p,t) strength above 2.7 MeV of excitation energy. The experimental results from the ${}^{122}\mathrm{Sn}{\mathrm{}(p,t)\mathrm{}}^{120}\mathrm{Sn}$ reaction have been used to discuss the role of the unpaired quasiparticle in ${}^{121}\mathrm{Sb}$ in determining the properties of its levels.

We present the first application of statistical spectroscopy to study the root-mean-square value of the parity nonconserving (PNC) interaction matrix element M determined experimentally by scattering longitudinally polarized neutrons from compound nuclei. Our effective PNC interaction consists of a standard two-body meson-exchange piece and a “doorway” term to account for $0^{-}$ spin-flip excitations. Strength functions are calculated using realistic single-particle energies and a residual strong interaction adjusted to fit the experimental density of states for the targets, ${}^{238}\mathrm{U}$ for $A\sim 230$ and ${}^{104,105,106,108}\mathrm{Pd}$ for $A\sim 100.$ Using the standard Desplanques-Donoghue-Holstein estimates of the weak PNC meson-nucleon coupling constants, we find that M is about a factor of 3 smaller than the experimental value for ${}^{238}\mathrm{U}$ and about a factor of 1.7 smaller for Pd. The significance of this result for refining the empirical determination of the weak-coupling constants is discussed.

Excitation functions from the interaction of fast neutrons (up to an energy of 250 MeV) on a target of ${}^{92}\mathrm{Mo}$ have been measured. Yields have been determined for reaction γ rays from ${}^{88-92}\mathrm{Mo},$ ${}^{88-92}\mathrm{Nb},$ ${}^{86-91}\mathrm{Zr},$ ${}^{84-86,88}\mathrm{Y},$ and ${}^{80,82-86}\mathrm{Sr}.$ These results are compared with model calculations using the GNASH code which takes into account compound nucleus, preequilibrium emission, multiple preequilibrium emission, and direct reaction contributions. The model calculations are in good agreement overall, but significant discrepancies emerge for some high-multiplicity, charged-particle-exit channels.

A backward angle measurement has been made of the angular distribution for the states in ${}^{24}\mathrm{Mg}$ that decay by symmetric fission to ${}^{12}\mathrm{C}{+}^{12}\mathrm{C}$ in the ${}^{12}\mathrm{C}{(}^{24}\mathrm{Mg}{,}^{12}{\mathrm{C}}^{12}\mathrm{C}{)}^{12}\mathrm{C}$ reaction. A comparison with previous very forward angle measurements indicates a substantial asymmetry in the angular distribution, averaged over a range of excitation energies in ${}^{24}\mathrm{Mg}.$ The observed degree of forward-backward asymmetry is reasonably well reproduced by coupled channels calculations assuming a direct inelastic scattering mechanism. Combining this information with previous measurements of the energy systematics supports direct inelastic excitation as the most likely reaction mechanism leading to the fissioning levels.

The temperature dependent relativistic mean field (RMF-T) results obtained by using nonlinear Lagrangian parameter set NL3 are presented for a few selected representative spherical and deformed nuclei. The calculated total binding energy (entropy) decrease (increase) as temperature $\mathrm{}\left(T\right)\mathrm{}$ increases. The depths of the potentials and the single particle (sp) energies change very little with temperature. The density slightly spreads out; as a result the radius increases as temperature rises. For well deformed nuclei the shell effects disappear at around $T\sim 3$ MeV. This value of T is relatively higher as compared to the corresponding value of T $(\sim 1.8$ MeV) obtained in the Strutinsky-type calculations. This difference in the value of T is shown to be due to the use of the effective nucleon mass $(<\mathrm{}$ the bare mass) appearing in the Skyrme III interaction or emerging from the RMF Lagrangian.

The effect of subcritical hadron bubbles on a first-order quark-hadron phase transition is studied. These subcritical hadron bubbles are created due to thermal fluctuations, and can introduce a finite amount of phase mixing (quark phase mixed with hadron phase) even at and above the critical temperature. For reasonable choices of surface tension and correlation length, as obtained from the lattice QCD calculations, we show that the amount of phase mixing at the critical temperature remains below the percolation threshold. Thus, as the system cools below the critical temperature, the transition proceeds through the nucleation of critical-size hadron bubbles from a metastable quark-gluon phase (QGP), within an inhomogeneous background populated by an equilibrium distribution of subcritical hadron bubbles. The inhomogeneity of the medium results in a substantial reduction of the nucleation barrier for critical bubbles. Using the corrected nucleation barrier, we estimate the amount of supercooling for different parameters controlling the phase transition, and briefly discuss its implications to cosmology and heavy-ion collisions.

We study the equation of state for neutron matter using the Walecka model including quantum corrections for baryons and sigma mesons through a realignment of the vacuum. We next use this equation of state to calculate the radius, mass, and other properties of rotating neutron stars.

High spin states of odd-odd nucleus ${}^{124}\mathrm{Cs}$ have been studied following the ${}^{116}\mathrm{Sn}{(}^{11}\mathrm{B},3n)$ reaction at a beam energy of 45 MeV. The previously reported isolated rotational bands are connected to each other by various linking transitions and to the $1^{+}$ ground state through different decay paths. The spin of the lowest observed state in the $\pi h_{11/2}\otimes \nu h_{11/2}$ yrast band is determined to be $9ħ,$ which is two units larger than that suggested by the latest in-beam study and confirms the spin assignment proposed by a recent systematics study on spin assignment and signature inversion of the $\pi h_{11/2}\otimes \nu h_{11/2}$ bands in odd-odd isotopes ${}^{118-132}\mathrm{Cs}.$

Prompt and delayed $\gamma$-ray coincidence measurements have located $(\nu h_{11/2}{)}^n$ yrast isomers in ${}^{125}\mathrm{Sn}$ and ${}^{126}\mathrm{Sn}$ among the products of heavy ion reactions on ${}^{124}\mathrm{Sn}$ targets. The decay properties of the two isomers are reported, and the results are related to those obtained for other tin isotopes in earlier works.

We investigate electroproduction of $\eta$ mesons below a W of 1.6 GeV, with particular emphasis on the roles of the $N^{*}\mathrm{}\left(1535\right)\mathrm{}$ and $N^{*}\mathrm{}\left(1520\right)\mathrm{}$ resonances. Using the effective Lagrangian approach, we show that the transverse helicity amplitude of $N^{*}\mathrm{}\left(1535\right)\mathrm{}$ can be extracted with good accuracy from the new data, under reasonable assumptions for the strength of the longitudinal helicity amplitude. In addition, although the differential cross section is found to have a small sensitivity to the $N^{*}\mathrm{}\left(1520\right)\mathrm{}$ resonance, it is shown that a recently completed double polarization experiment is very sensitive to this resonance.

We describe the properties of quark matter at zero temperature and finite baryon densities within microscopic Vlasov/molecular dynamics approaches. We explicitly demonstrate that the Vlasov approach alone is insufficient in the hadronization region. In order to overcome this problem we use molecular dynamics with frictional cooling and a Thomas-Fermi approximation to the Fermi motion. We find some evidence for a second order phase transition from nuclear to quark matter at high baryon densities. At low densities the quarks condensate into approximately color white clusters (nucleon).

Level statistics and reduced transition probability distributions have been analyzed over the region $E_x=0\mathrm{}–8014\mathrm{keV}$ in ${}^{30}\mathrm{P}$ and compared to previous results from ${}^{26}\mathrm{Al}.$ The level statistics in ${}^{30}\mathrm{P}$ show clear evidence of broken isospin symmetry and are very similar to those from ${}^{26}\mathrm{Al}.$ Transition distributions in the two nuclides are different, but both suggest that the broken symmetry also affects the transitions.

We use the random phase approximation to describe the muon capture rate on ${}^{44}\mathrm{Ca},$ ${}^{48}\mathrm{Ca},$ ${}^{56}\mathrm{Fe},$ ${}^{90}\mathrm{Zr},$ and ${}^{208}\mathrm{Pb}.$ With ${}^{40}\mathrm{Ca}$ as a test case, we show that the continuum random phase approximation (CRPA) and the standard RPA give essentially equivalent descriptions of the muon capture process. Using the standard RPA with the free nucleon weak form factors we reproduce the experimental total capture rates on these nuclei quite well. Thus, unlike the allowed $\beta$ decays, with very small momentum transfer and exclusively the $1^{+}$ multipole, the muon capture rate, with momentum transfer of approximately muon mass magnitude, and a mixture of multipoles (dominated by $1^{-}),$ does not require any quenching of the axial-vector coupling constant.

Microscopic and macroscopic distorted wave Born approximation calculations have been performed using molecular, Michel and normal optical potentials to analyze the angular distributions of cross sections for 12 transitions populating the 0.0, 0.709, 1.454, 1.974, 2.538, 2.72, 2.84, 3.02, 3.93. 4.62, 5.42, and 7.20 MeV states of ${}^{30}\mathrm{P}$ via the $(\alpha ,d)$ reaction. Only the molecular potential is able to produce satisfactory fits to the data, but the normal optical potential is found to be inadequate in accounting for the large-angle data and the Michel potential is just unsatisfactory. The spectroscopic factors for the d-cluster transfer are deduced from the full finite-range distorted-wave Born approximation and compared to the shell-model predictions for the even-parity states.The spin-parity assignment of the 3.93 MeV state is confirmed. The best-fit value for the finite-range parameter for the zero-range DWBA calculations is also deduced.

The differential cross section of the ${}^{28}\mathrm{Si}(\alpha {,p)}^{31}\mathrm{P}$ reaction for 26 MeV incident energy has been analyzed in the distorted wave Born approximation (DWBA) with zero and full-finite range using a deep and shallow optical, Michel and molecular potentials in the incident channel, and a usual optical model potential for proton in the final channel. The parameters of potential in the entrance channel are determined from the elastic scattering data. The calculations done with the deep optical and Michel potentials reproduce the structure of the angular distributions reasonably well, but fail to account for the absolute magnitudes by a few orders. The shallow optical one is satisfactory up to about ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=100\mathrm{}°.$ The molecular potential, on the other hand, reproduces both the absolute cross sections and the pattern of the angular distributions. Coupled-channels Born approximation calculations improve fits to the data over the DWBA predictions.

The ${10}^{+}$ and ${27/2}^{-}$ isomers of the $Z>\mathrm{}64,$ $N=82\mathrm{}$ nuclei are investigated in the shell-model framework. We derive an extended seniority reduction formula for the relevant $E2\mathrm{}$ transition strengths. Based on the extended formula, as well as on the approximate degeneracy among the ${0h}_{11/2},$ ${2s}_{1/2},$ and ${1d}_{3/2}$ orbits, we argue that the $B\left(E2\mathrm{}\right)\mathrm{}$ data require the ${}^{146}\mathrm{Gd}$ core excitation. The energy levels of both parities and the $B\left(E2\mathrm{}\right)\mathrm{}$ values are simultaneously reproduced by a multi-$j$ shell-model calculation with the modified surface-delta interaction, if the excitations from ${(0g}_{7/2}{1d}_{5/2})$ to ${(0h}_{11/2}{2s}_{1/2}{1d}_{3/2})$ are taken into account.

We have investigated the sub-barrier fusion between spherical projectiles and well-deformed targets in ${}^{60}\mathrm{Ni}{+}^{154}\mathrm{Sm}$ and ${}^{32}\mathrm{S}{+}^{182}\mathrm{W}$ reactions, and both lead to the same compound nucleus ${}^{214}\mathrm{Th}.$ In order to get direct evidence that the projectile really fuses with the deformed target, the fusion evaporation residues emitted to the beam direction were measured by using the JAERI recoil mass separator and identified on the basis of time- and position-correlated $\alpha$ decays. The angular distributions of fission fragments were also measured to obtain the total fusion cross section. The measured cross sections of the fusion fission and the fusion evaporation were compared with the results of the coupled channel calculation and the statistical model calculation, respectively. In the ${}^{32}\mathrm{S}{+}^{182}\mathrm{W}$ system, a good agreement between them was obtained for $xn,$ $pxn,$ and $\alpha \mathrm{xn}$ channels. In the heavy projectile system of ${}^{60}\mathrm{Ni}{+}^{154}\mathrm{Sm},$ on the other hand, the observed evaporation residue cross sections below the Bass barrier were much less than the calculated results whereas they were well reproduced above the barrier. It was found that this large hindrance could be reproduced by assuming an extra-extra push energy of around 20 MeV in the tip collision of the deformed target and nearly zero in the side collision.