The fission barriers of the nuclei ${}^{254}\mathrm{Fm},$ ${}^{256}\mathrm{Fm},$ ${}^{258}\mathrm{Fm},$ ${}^{258}\mathrm{No}$, and ${}^{260}\mathrm{Rf}$ are investigated in a fully microscopic way up to the scission point. The analysis is based on the constrained Hartree-Fock-Bogoliubov theory and Gogny’s D1S force. The quadrupole, octupole, and hexadecapole moments as well as the number of nucleons in the neck region are used as constraints. Two fission paths, corresponding to the bimodal fission, are found. The decrease with isotope mass of the half-life times of heavy Fm isotopes is also explained.

High-spin states have been studied in neutron-deficient ${}_{57}^{124}{\mathrm{La}}_{67},$ populated through the ${}^{64}\mathrm{Zn}{(}^{64}\mathrm{Zn},3pn)$ reaction at 260 MeV. The Gammasphere $\gamma$-ray spectrometer has been used in conjunction with the Microball charged-particle detector, the Neutron Shell, and the Argonne Fragment Mass Analyzer, in order to select evaporation residues of interest. The known band structures have been extended and new bands found. Most of the bands are linked together, allowing more consistent spin and parity assignments. Comparison of band properties to cranking calculations has allowed configuration assignments to be made and includes the first identification of the $g_{9/2}$ proton-hole in an odd-odd lanthanum isotope. Two bands have been assigned a $\pi h_{11/2}\otimes \nu h_{11/2}$ structure; the yrast one exhibits a signature inversion in its level energies below $I=18.5\mathrm{}ħ,$ while the excited one exhibits a signature inversion above $I=18.5\mathrm{}ħ.$

The possibility to extract relevant information on spectroscopic factors from ${(e,e}^{\prime }p)$ reactions at high $Q^2$ is studied. Recent ${}^{16}\mathrm{O}{(e,e}^{\prime }p)$ data at $Q^2=0.8\mathrm{}\hspace{0.5em}(\mathrm{GeV}{/c)}^2$ are compared to a theoretical approach that includes an eikonal description of the final-state interaction of the proton, a microscopic nuclear matter calculation of the damping of this proton, and high-quality quasihole wave functions for p-shell nucleons in ${}^{16}\mathrm{O}.$ Good agreement with the $Q^2=0.8\mathrm{}\hspace{0.5em}(\mathrm{GeV}{/c)}^2$ data is obtained when spectroscopic factors are employed that are identical to those required to describe earlier low-$Q^2$ experiments.

We derive the formalism for the leading order corrections to the adiabatic approximation to the scattering of composite projectiles. Assuming a two-body projectile of core plus loosely bound valence particle and a model (the core recoil model) in which the interaction of the valence particle and the target can be neglected, we derive the nonadiabatic correction terms both exactly, using a partial wave analysis, and using the eikonal approximation. Along with the expected energy dependence of the corrections, there is also a strong dependence on the valence-to-core mass ratio and on the strength of the imaginary potential for the core-target interaction, which relates to absorption of the core in its scattering by the target. The strength and diffuseness of the core-target potential also determine the size of the corrections. The first order nonadiabatic corrections were found to be smaller than qualitative estimates would expect. The large absorption associated with the core-target interaction in such halo nuclei as ${}^{11}\mathrm{Be}$ kills off most of the nonadiabatic corrections. We give an improved estimate for the range of validity of the adiabatic approximation when the valence-target interaction is neglected, which includes the effect of core absorption. Some consideration was given to the validity of the eikonal approximation in our calculations.

The dependence of the radiative energy loss of hard partons $(E>\mathrm{}10\mathrm{}\hspace{0.5em}\mathrm{GeV})$ on the initial thermodynamic parameters is studied for deconfined matter to be expected at the Relativistic Heavy-Ion Collider (RHIC). We demonstrate that the specific QCD radiation pattern with a nonlinear dependence of the energy loss on the propagated distance leads to a strong increase of the energy loss with increasing initial entropy of deconfined matter supposing its lifetime is less than the average time to pass through the medium. This is in contrast to a parametrization with constant energy loss per unit length of propagation. For a sufficiently high initial temperature a two-regime behavior of the energy loss as a function of the initial parton momentum occurs. The angular structure of the energy loss of hard jets with respect to the initial temperature is also discussed for RHIC conditions.

Some aspects of $a_0^0$-$f_0$ mixing effects in the reaction $\overrightarrow{p}\overrightarrow{n}{\mathrm{da}}_0^0$ with perpendicular polarized proton beam are discussed. An angular-asymmetry parameter A is defined to study those effects. It is shown that, for energies close to the production threshold, the angular-asymmetry parameter $A(\theta ,\phi )$ is proportional to the $a_0^0$-$f_0$ mixing amplitude for arbitrary polar and azimuthal angles $\theta$ and $\phi$ of the outgoing $a_0$ meson. This statement is also valid for arbitrary energies, but then only at polar angles $\theta =0\mathrm{}°$ and $\theta =90\mathrm{}°.$ The mass dependence of the differential cross section $d\sigma {/dm}_{{\pi }^0\eta }$ in the reaction $p\overrightarrow{n}d{\pi }^0\eta$ in the presence of $a_0^0$-$f_0$ mixing is also discussed.

Consideration of Coulomb energy for the lowest $0^{+}$ states with $T=2\mathrm{}$ in $A=16\mathrm{}$ allow a determination of the $s^2{/d}^2$ mixture in those states. We also discuss the behavior of the ${2s}_{1/2}$ occupancy as a function of A for nearby nuclei.

The weak ${\pi }^{-}$ decay of ${}_{\Lambda \Lambda }^4\mathrm{H}$ is theoretically analyzed and compared with a recent BNL-E906 experiment. The two-body ${\pi }^{-}$ decay width of ${}_{\Lambda \Lambda }^4\mathrm{H}$ is calculated to be $0.69{\Gamma }_{\Lambda },$ and its branching ratio to the total ${\pi }^{-}$ decay is determined to be about 25%. The branching ratio of decay channels accompanied by a $\Lambda$ particle to the total ${\pi }^{-}$ decay is about 43%. The calculated ${\pi }^{-}$ spectrum of ${}_{\Lambda \Lambda }^4\mathrm{H}$ has a broad peak around $100\hspace{0.5em}\mathrm{MeV}/c$ in the nuclear continuum region, whose value is inconsistent with the experimental result of a peak structure around $104\hspace{0.5em}\mathrm{MeV}/c.\mathrm{}$ The other possible decays within the $104\hspace{0.5em}\mathrm{MeV}/c$ peak are reanalyzed, that is $\Lambda$-hypernuclear pair decays of ${}_{\Lambda }^3\mathrm{H}$ and ${}_{\Lambda }^6\mathrm{He},$ which decay into excited states of ${}^6\mathrm{Li}.$

The mass dependence of the $M3Y$-type effective interactions and the effects of tensor correlations are examined. Two-body nuclear matrix elements are obtained by the lowest order constrained variational technique with and without tensor correlations. We have found that the tensor correlations are important especially in the triplet-even and tensor-even channels in order to reproduce the G-matrix elements obtained previously. Then $M3Y$-type potentials for inelastic scattering are obtained by fitting our two body matrix elements to those of a sum of Yukawa functions for the mass numbers $A=16,$ $A=24,$ $A=40,$ and $A=90.\mathrm{}$

The consequences of hadrochemical freeze-out for the subsequent hadron gas evolution in central heavy-ion collisions at Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC) energies are discussed with special emphasis on effects due to antibaryons. Contrary to naive expectations, their individual conservation, as implied by experimental data, has significant impact on the chemical off-equilibrium composition of hadronic matter at collider energies. This may reflect on a variety of observables including source sizes and dilepton spectra.

The half-life of the $\beta {\beta }_{2\nu }$ decay of ${}^{160}\mathrm{Gd}$ is estimated by including the pairing interaction within the pseudo-SU(3) model. This process was previously reported as theoretically forbidden in the context of that model, however, the pairing interaction is able to mix different occupations and opens new channels for the decay. Explicit expressions are presented for the mixing induced by the pairing force. Matrix elements for the $\beta {\beta }_{2\nu }$ and $\beta {\beta }_{0\nu }$ decays are now calculated by assuming both a dominant component in the wave function of the ground state of ${}^{160}\mathrm{Gd}$ and a more general model space. The results, of the calculated $\beta \beta$ half-lives, suggest that the planned experiments would succeed in detecting the $\beta {\beta }_{2\nu }$ decay of ${}^{160}\mathrm{Gd}$ and, eventually, would improve the limits for the zero-neutrino mode.

A high-precision measurement of excitation energies in ${}^{22}\mathrm{Mg}$ was performed using the ${}^{25}\mathrm{Mg}{(}^3\mathrm{He}{,}^6\mathrm{He}{)}^{22}\mathrm{Mg}$ reaction as a different approach to study this proton-rich, astrophysically interesting nucleus. The reaction was studied at 51.0 MeV with the Enge split-pole spectrograph at Yale. Proton-unbound states at 6.051(4) and 6.329(6) MeV were observed, confirming a recent identification of these new states with the ${}^{24}\mathrm{Mg}{\mathrm{}(p,t)\mathrm{}}^{22}\mathrm{Mg}$ reaction. There is no evidence in our data of a previously reported state at 5.837 MeV.

The $\alpha$ decay of ${}^{183}\mathrm{Pb}$ has been studied in detail at the focal plane of the RITU gas-filled separator. The four previously known $\alpha$ decay branches have been ordered into the decay of two isomers in ${}^{183}\mathrm{Pb}.$ The deduced decay scheme and the interpretation of the inferred $\alpha$ decay hindrance factors and $\gamma$ rays observed at the focal plane are strongly in favor of the recent suggestion of triple shape coexistence—oblate, prolate, and near-spherical in the daughter nucleus ${}^{179}\mathrm{Hg}.$

High-spin states in ${}^{123}\mathrm{Xe}$ were populated in $\mathrm{the}{\hspace{0.5em}}^{110}\mathrm{Pd}{(}^{18}\mathrm{O},5n)$ reaction at 75 MeV and gamma-ray coincidences were measured with the GASP spectrometer. A new rotational sequence of enhanced dipole transitions was established. This band, as well as a similar band $\mathrm{in}{\hspace{0.5em}}^{124}\mathrm{Xe},$ may be described within the framework of the tilted axis cranking model as bands for which comparable amounts of angular momentum are generated by magnetic and collective rotation, respectively.

The yrast states in the neutron deficient $N=90\mathrm{}$ nucleus ${}^{166}\mathrm{Os}$ have been extended to $J\approx 12ħ$ (possibly $14ħ)$ and two sidebands have been established. Transitions in ${}^{165}\mathrm{Os}$ have been observed for the first time. These nuclei were populated using the ${}^{106}\mathrm{Cd}{(}^{64}\mathrm{Zn}{,2pxn)}^{168-x}\mathrm{Os}$ reaction at a beam energy of 334 MeV. The emitted $\gamma$ rays were detected with the Jurosphere $\gamma$-ray spectrometer, while the recoiling nuclei were identified using an active stopper at the focal plane of the gas-filled separator RITU by recoil decay tagging. The observed states are discussed in terms of the systematics of the osmium nuclei in the transitional region as the $N=82\mathrm{}$ shell closure is approached.

The agreement of elliptic flow data at RHIC at central rapidity with the hydrodynamic model has led to the conclusion of very rapid thermalization. This conclusion is based on the intuitive argument that hydrodynamics, which assumes instantaneous local thermalization, produces the largest possible elliptic flow values and that the data seem to saturate this limit. We here investigate the question whether incompletely thermalized viscous systems may actually produce more elliptic flow than ideal hydrodynamics. Motivated by the extremely fast primordial longitudinal expansion of the reaction zone, we investigate a toy model that exhibits thermalization only in the transverse directions but undergoes collisionless free-streaming expansion in the longitudinal direction. For collisions at RHIC energies, elliptic flow results from the model are compared with those from hydrodynamics. With the final particle yield and $k_{\perp }$ distribution fixed, the transversally thermalized model is shown not to be able to produce the measured amount of elliptic flow. This investigation provides further support for very rapid local kinetic equilibration at RHIC. It also yields interesting novel results for the elliptic flow of massless particles such as direct photons.

In this work we investigate the effects of the $\rho -\omega$ mixing term in infinite nuclear matter and also in finite nuclei in the context of the nonlinear Walecka model solved in a Thomas-Fermi approximation for the TM1 and NL3 parametrizations. We conclude that, for the accepted experimental value for the mixing term strength, its effects on infinite nuclear matter are almost negligible but the symmetry energy in the TM1 parametrization would be sensitive to a higher value of the mixing term strength. The effect of the mixing term reinforces the Coulomb interaction effect, giving less binding to the protons. For infinite matter the contribution from the isospin mixing term to the binding energy is proportional to the asymmetry parameter $\delta .$ For finite nuclei the contribution of the isospin mixing term is sensitive to the inclusion or noninclusion of the Coulomb field and shows finite size effects.

The uncertain origin of the proton rich Mo and Ru isotopes has motivated cross-section measurements of α- and neutron-induced reactions. The experiments were performed via the activation technique by irradiating thin layers of natural ruthenium with α-particle beams close to the Gamov window of the p process between 7.0 and 10.5 MeV. The cross sections of the reactions ${}^{96}\mathrm{Ru}(\alpha ,\gamma ),$ ${}^{96}\mathrm{Ru}(\alpha ,n),$ ${}^{96}\mathrm{Ru}(\alpha ,p),$ and ${}^{98}\mathrm{Ru}(\alpha ,n)$ could be determined with uncertainties of typically 10%. On average, these results are about two to three times smaller than recent statistical model predictions. Additional activations in a quasistellar neutron spectrum corresponding to $kT=25\mathrm{}\mathrm{keV}$ allowed us to obtain the complementary stellar $(n,\gamma )$ cross sections for ${}^{96}\mathrm{Ru},$ ${}^{102}\mathrm{Ru},$ and ${}^{104}\mathrm{Ru}.$ In these cases the agreement with model calculations is considerably better.

We discuss in the framework of linear muffin-tin orbital method and Bahcall’s calculations how the ratio of L- to K-shell electron capture rates $(L/K$ ratio) in ${}^7\mathrm{Be}$ would be affected by the host medium in which ${}^7\mathrm{Be}$ is implanted. Our calculations show that the recently observed discrepancy between the measured and observed $L/K$ ratio in ${}^7\mathrm{Be}$ could be understood quantitatively as a result of in-medium effects distorting the L-shell electron orbital of ${}^7\mathrm{Be}.$

The hypernucleus ${}_{\Lambda }^9\mathrm{Be}$ is investigated using the $\alpha +\Lambda +\alpha$ cluster model. The corresponding Faddeev equations are solved for different $\alpha -\alpha$ and $\Lambda -\alpha$ interactions that describe both ${}^8\mathrm{Be}$ and ${}_{\Lambda }^5\mathrm{He}$ energy spectra. For the ground state $J^{\pi }={\frac{1}{2}}^{+}$ and excited states ${\frac{3}{2}}^{+}$ and ${\frac{5}{2}}^{+}$ we include the Coulomb repulsion between the $\alpha ’\mathrm{s}$ and calculate, in addition to the energy eigenvalues, the Coulomb energy, the $\alpha$- and $\Lambda$-particle mean radius, the rms charge radius, the electric quadrupole moment $\mathrm{}\left(Q\right),$ as well as the magnetic dipole $\left(\mu \right)$ and octopole $\left({\mu }_3\right)$ moments. To the best of our knowledge these observables have not yet been measured and, therefore, our calculation constitutes the first prediction. Structural differences between ${}^9\mathrm{Be}$ and ${}_{\Lambda }^9\mathrm{Be}$ lead to values of Q and $\mu$ that have opposite sign. Unlike previous theoretical work we find only two degenerate negative parity resonances ${\frac{1}{2}}^{-}\left({\frac{3}{2}}^{-}\right)$ but, in addition, we get two degenerate positive parity resonances with $J^{\pi }={\frac{7}{2}}^{+}\left({\frac{9}{2}}^{+}\right)$ at higher energy which, together with the bound states, complete the positive parity rotational band.