The $\alpha$ decay of ${}^{225}\mathrm{Ac}$ to ${}^{221}\mathrm{Fr}$ was reinvestigated by $\gamma$-ray spectroscopic studies with HPGe detectors and ${}^{225}\mathrm{Ac}$ sources purified using continuous elution processes. Energies and intensities of about 120 $\gamma$-ray transitions were measured. Among these, 40 are reported for the first time. A ${}^{221}\mathrm{Fr}$ level scheme with 46 excited states and 124 transitions is proposed. The level structure is described in terms of a reflection asymmetric structure with parity doublet bands $K^{\pi }{=1/2\mathrm{}}^{\pm },$ ${3/2}^{\pm },$ ${5/2}^{\pm },$ and ${3/2}^{\pm }$ in order of increasing energy. Both strong and intermediate coupling models have been shown to be in good agreement with the experimental data.

We present a new cascade-type microscopic simulation of nucleus-nucleus collisions at RHIC energies. The basic elements are partons (quarks and gluons) moving in $8N$-dimensional phase space according to Poincaré-covariant dynamics. The parton-parton scattering cross sections used in the model are computed within perturbative QCD in the tree-level approximation. The $Q^2$ dependence of the structure functions is included by an implementation of the DGLAP mechanism suitable for a cascade, so that the number of partons is not static, but varies in space and time as the collision of two nuclei evolves. The resulting parton distributions are presented, and meaningful comparisons with experimental data are discussed.

A simple model of a composite nucleon is developed in which a fermion and a boson, representing quark and diquark constituents of the nucleon, form a bound state owing to a contact interaction. Photon and pion couplings to the quark provide vertex functions for the photon and pion interactions with the composite nucleon. By a suitable choice of cutoff parameters of the model, realistic electromagnetic form factors are obtained for the proton. When a pseudoscalar pion-quark coupling is used, the pion-nucleon coupling is predominantly pseudovector. A virtual photopion amplitude is considered in which there are two types of contributions: hadronic contributions where the photon and pion interactions have an intervening propagator of the nucleon or its excited states, and contactlike contributions where the photon and pion interactions occur within a single vertex. At large Q, the contactlike contributions are dominant. The model nucleon exhibits scaling behavior in deep-inelastic scattering and the normalization of the parton distribution provides a rough normalization of the contactlike contributions. Calculations for the virtual photopion amplitude are performed using kinematics appropriate to its occurrence as a meson-exchange current in electron-deuteron scattering. The results suggest that the contactlike terms can dominate the meson-exchange current for $Q>\mathrm{}1\mathrm{}\mathrm{GeV}/c.\mathrm{}$ There is a direct connection of the contactlike terms to the off-forward parton distributions of the model nucleon.

A recent Coulomb excitation study has called into question the $4^{+}$ spin assignment of the 1414-keV level in ${}^{232}\mathrm{Th},$ which had earlier been interpreted as a two-phonon $\gamma$-vibrational excitation, and had suggested instead a $3^{-}$ assignment. Data obtained in the present neutron scattering study of ${}^{232}\mathrm{Th}$ are inconsistent with the $3^{-}$ suggestion and support an $I^{\pi }{=4\mathrm{}}^{+}$ assignment for the 1414-keV level, lending credence to the argument that it is a $K^{\pi }{=4\mathrm{}}^{+}$ band head.

The $\omega$ variation of moments of inertia of superdeformed bands is investigated by a particle-number conserving (PNC) method of the cranked shell model Hamiltonian with monopole and quadrupole pairings. The observed $\omega$ dependence of the moments of inertia for ${}^{192,194}\mathrm{Hg}\mathrm{}\left(1\right),$ particularly the shift in $J^{\mathrm{}\left(2\right)\mathrm{}}$ downturn for ${}^{194}\mathrm{Hg}\mathrm{}\left(1\right)\mathrm{}$ to a higher frequency, are well reproduced by the PNC calculation. The microscopic mechanism of the $\omega$ dependence of $J^{\mathrm{}\left(2\right)\mathrm{}}$ (contribution to $J^{\mathrm{}\left(2\right)\mathrm{}}$ from each cranked Nilsson orbital) is clearly exhibited in the PNC calculation. The shift of the $J^{\mathrm{}\left(2\right)\mathrm{}}$ downturn for ${}^{194}\mathrm{Hg}\mathrm{}\left(1\right)\mathrm{}$ is mainly attributed to the protons in the $N=6\mathrm{}$ intruder orbitals under the influence of $Q_{20}$ quadrupole pairing.

We have measured the $\alpha$-particle spectra at different laboratory angles from the fusion reaction ${}^{16}\mathrm{O}{+}^{54}\mathrm{Fe}$ at 110 MeV. The results are compared with the ${}^{28}\mathrm{Si}{+}^{27}\mathrm{Al}$ symmetric system. In the case of the asymmetric ${}^{16}\mathrm{O}{+}^{54}\mathrm{Fe}$ system $\alpha$ spectra are consistent with the predictions of the statistical model calculations but in the case of the symmetric ${}^{28}\mathrm{Si}{+}^{27}\mathrm{Al}$ system, experimental spectra deviate at higher as well as at lower energies from the statistical model calculations. The results are also compared with a less asymmetric ${}^{28}\mathrm{Si}{+}^{51}\mathrm{V}$ system. There is a systematic change in the formation time of the compound nucleus as we move from the asymmetric to the symmetric systems. The dynamical trajectory model calculations have been done to understand the possible entrance channel effects on the formation and the decay of the compound nucleus.

A simple two level mixing model is employed to perform a Monte Carlo simulation for the decay out of the superdeformed bands SD-1 and SD-3 in ${}^{194}\mathrm{Hg}.$ An exponential spin dependence of the interaction between superdeformed and normally deformed states is applied. Average intraband intensities and transition quadrupole moments are determined at each spin. The simple two level mixing approach is consistent with more sophisticated theoretical models. The Monte Carlo approach allows one to determine probabilities for the reproduction of the experimental intensity patterns and transition quadrupole moments. An interaction of $v\approx 0.5\hspace{0.5em}\mathrm{eV}$ was determined for spin $12ħ$ in the yrast SD band. The results show that the decay out of the yrast and excited SD bands in ${}^{194}\mathrm{Hg}$ can be described with the same spin dependent interaction.

Excited states have been observed for the first time in the neutron deficient nuclei ${}^{166}\mathrm{Os}$ and ${}^{164}\mathrm{Os}.$ The nuclei were produced using the reactions ${}^{106}\mathrm{Cd}{(}^{63}\mathrm{Cu}{,p2n)}^{166}\mathrm{Os},$ ${}^{112}\mathrm{Sn}{(}^{58}\mathrm{Ni}{,2p2n)}^{166}\mathrm{Os},$ and ${}^{106}\mathrm{Cd}{(}^{60}\mathrm{Ni}{,2n)}^{164}\mathrm{Os}$ at beam energies of 292, 286, and 257 MeV, respectively. The $\gamma$ rays emitted by ${}^{166}\mathrm{Os}$ and ${}^{164}\mathrm{Os}$ were identified by correlating the associated recoil evaporation residues with their subsequent characteristic α decays. The deduced level schemes indicate that ${}^{166}\mathrm{Os}$ and ${}^{164}\mathrm{Os}$ continue the trend of decreasing deformation moving away from the $N=104\mathrm{}$ midshell. The level energy systematics of the low-spin states are presented.

For the first time, the relativistic mean field (RMF) model is applied to the shears band recently observed in ${}_{37}^{84}\mathrm{Rb}.$ Signals of the appearance of the shears mechanism, such as smooth decreases of the shears angle and of the $B\left(M1\mathrm{}\right)/B\left(E2\mathrm{}\right)\mathrm{}$ ratio while keeping the nearly constant tilt angle, are well reproduced. Thus it is shown that the microscopic RMF model can nicely describe the shears band in this nucleus.

Using the statistical model and the fission and the neutron evaporation characteristics predicted in different theoretical models, we analyze the survival probabilities of superheavy nuclei produced in ${}^{208}\mathrm{Pb}$-based cold fusion reactions. For $Z<\mathrm{}114\mathrm{}$ all models give similar ratios of the neutron evaporation to the fission width. But for $Z>~114,$ they yield different results for this ratio and therefore lead to different evaporation residue cross sections.

Excited states in ${}^{196}\mathrm{Au},$ populated in the ${}^{196}\mathrm{Pt}\mathrm{}(p,n)\mathrm{}$ and $\mathrm{}(d,2n)\mathrm{}$ reactions, were investigated by in-beam $\gamma$-ray and conversion-electron spectroscopy. Two only weakly connected level structures, built on the $2^{-}$ ground state (negative-parity level scheme) and on the $5^{+}$ isomer at $84.7$ keV (positive-parity level scheme), are observed. The point of main effort of the present work was the investigation of the negative-parity level scheme in connection with its description within the framework of an extended supersymmetry. For this level scheme we observe 25 excited states up to an excitation energy of $500$ keV, of which 23 had already been identified in a recent study of ${}^{196}\mathrm{Au}$ by transfer reactions. From 500 to $800$ keV we observe 28 additional levels compared to 20 levels observed in the transfer reactions. The excitation energies derived in the studies of the $\mathrm{}(p,n)\mathrm{}$ compound reaction and the $\mathrm{}(p,d)\mathrm{}$ transfer reaction agree within 1 keV, and the complementary information obtained from the two reactions led to improved spin determinations. The negative-parity level structure is compared with the predictions of the extended supersymmetry.

Emission-energy distributions were measured for the inclusive ${}^{40}\mathrm{Ca}{(p,p}^{\prime })$ reaction at an incident energy of 392 MeV and an angular range between 25° and 120°. A semiclassical distorted wave (SCDW) model gives a reasonably good description of the experimental data. The extent to which the observed yields are dominated by a two-particle rescattering emission contribution is estimated by a theoretical method that is known to describe experimental data for ${}^{40}\mathrm{Ca}{(p,p}^{\prime }{p}^{″})$ reasonably well. The energy distribution of the two-particle inclusive yield is found to agree well with the first-step contribution of the SCDW theory. Consequently this suggests strongly that the inclusive ${(p,p}^{\prime })$ yield at forward angles and high emission energy consists mostly of two high-energy nucleons emitted in the first step of the collision.

The inclusive $\left(\overrightarrow{p}{,}^3\mathrm{He}\right)$ reactions on ${}^{59}\mathrm{Co}$ and ${}^{93}\mathrm{Nb}$ were investigated at an incident energy of 100 MeV. Emission-energy distributions for cross sections as well as analyzing powers, were measured from a threshold of $\sim 35\hspace{0.5em}\mathrm{MeV},$ determined by the detector configuration, up to the kinematic maximum. An angular range from 15° to 140° (lab) was covered. The experimental distributions were compared with a multistep direct theory in which a reaction mechanism based on deuteron pickup is employed. Reasonable agreement between experimental double differential cross sections and analyzing powers and the theoretical expectation is obtained.

The transverse momentum spectra of secondary ${\pi }^{-}$ mesons and participant protons in central C+C and C+Ta interactions at $4.2A$ GeV/c beam momentum have been analyzed within a collective flow model and a boundary model. All the particle spectra within a collective flow model at a given beam energy can be reproduced with a single set of intensive parameters for the initial state of fireball. As typical freeze-out parameters in this beam energy region we find a freeze-out temperature $T=(55\mathrm{}–100)\hspace{0.5em}\mathrm{MeV},$ and an average transverse expansion velocity at freeze-out $〈\beta 〉=0.30\mathrm{}–\mathrm{0.39.}$ The pion spectra within a boundary model including the quantum mechanical effects can be described well. To fit the proton spectra well, within a boundary model, one will need to introduce the transverse collective expansion.

The effects of both kinematical and dynamical SU(6) breaking on the nucleon elastic form factors, $G_E^N{(Q}^2)$ and $G_M^N{(Q}^2),$ are investigated within the constituent quark model formulated on the light front. The investigation is focused on $G_E^n{(Q}^2)$ and the ratio $G_M^p{(Q}^2{)/G}_M^n{(Q}^2),$ which within the SU(6) symmetry are given by $G_E^n{(Q}^2)=0\mathrm{}$ and $G_M^p{(Q}^2{)/G}_M^n{(Q}^2)=-3/2,$ respectively. It is shown that the kinematical SU(6) breaking caused by the Melosh rotations of the quark spins as well as the dynamical SU(6) breaking due to the mixed-symmetry component generated in the nucleon wave function by the spin-dependent terms of the quark-quark interaction, can affect both $G_E^n{(Q}^2)$ and $G_M^p{(Q}^2{)/G}_M^n{(Q}^2).\mathrm{}$ The calculated $G_E^n{(Q}^2)$ is found to be qualitatively consistent with existing data, though only $\simeq 65\%$ of the experimental neutron charge radius can be explained without invoking effects from possible nonvanishing sizes of the constituent quarks and/or many-body currents. At the same time the predictions for the magnetic ratio $G_M^p{(Q}^2{)/G}_M^n{(Q}^2)$ turn out to be inconsistent with the data. It is, however, shown that the calculations of $G_M^N{(Q}^2)$ based on different components of the one-body electromagnetic current lead to quite different results. In particular, the calculations based on the plus component are found to be plagued by spurious effects related to the loss of the rotational covariance in the light-front formalism. These unwanted effects can be avoided by considering the transverse y component of the current. In this way our light-front predictions are found to be consistent with the data on both $G_E^n{(Q}^2)$ and $G_M^p{(Q}^2{)/G}_M^n{(Q}^2).\mathrm{}$ Finally, it is shown that a suppression of the ratio $G_E^p{(Q}^2{)/G}_M^p{(Q}^2)$ with respect to the dipole-fit prediction can be expected in the constituent quark model provided the relativistic effects generated by the Melosh rotations of the constituent spins are taken into account.

We have measured the ${}^8\mathrm{Li}(\alpha {,n)}^{11}\mathrm{B}$ reaction directly and exclusively, and determined the total cross sections in the center-of-mass energy of 1.5–7.0 MeV, by using a new-type gas counter, multiple-sampling and tracking proportional chamber (MSTPC), and neutron counters. This experiment was performed in the condition of inverse kinematics. The ${}^8\mathrm{Li}$ beam was produced by the RIKEN projectile-fragment separator, and injected into the MSTPC filled with ${}^4\mathrm{He}$ gas, which worked as a detector gas and served as a target. The reaction cross section obtained in the present exclusive measurement is about half of the one obtained in previous inclusive measurements.

The cluster distributions of three different systems are examined to search for signatures of a continuous phase transition. In a system known to possess such a phase transition, both sensitive and insensitive signatures are present; while in systems known not to possess such a phase transition, only insensitive signatures are present. It is shown that nuclear multifragmentation results in cluster distributions belonging to the former category, suggesting that the fragments are the result of a continuous phase transition.

We use relativistic mean field theory, which includes scalar and vector mesons, to calculate the binding energy and charge radii in ${}^{125}\mathrm{Cs}{-}^{139}\mathrm{Cs}.$ We then evaluate the nuclear structure corrections to the weak charges for a series of cesium isotopes using different parameters and estimate their uncertainty in the framework of this model.

The systematics of $\alpha$-nucleus folding potentials is extended to the system ${}^{209}\mathrm{Bi}{-\mathrm{}}^6\mathrm{He}$ where recently anomalously large reaction cross sections have been observed. These anomalies, which have been explained by the large spatial extent of the ${}^6\mathrm{He}$ wave function, can be described with systematic folding potentials in a natural way.

Lattice quantum chromodynamics results provide an opportunity to model, and extrapolate to finite baryon density, the properties of the quark-gluon plasma (QGP). Upon fixing the scale of the thermal coupling constant and vacuum energy to the lattice data, the properties of resulting QGP equations of state (EoS) are developed. We show that the physical properties of the dense matter fireball formed in heavy ion collision experiments at CERN-SPS are well described by the QGP-EoS we presented. We also estimate the properties of the fireball formed in early stages of nuclear collision, and argue that QGP formation must be expected down to $40A$ GeV in central Pb-Pb interactions.