The dynamical model based on the asymmetric mass division has been applied to calculate pre-scission neutron multiplicity from heavy-ion induced fusion-fission reactions. Links between the pre-scission neutron multiplicity, excitation energy, and asymmetric mass distribution are clarified based on the Monte Carlo simulation and Langevin dynamics. The pre-scission neutron multiplicity is calculated and compared with the respective experimental data over a wide range of excitation energy and nonconstant viscosity. The analysis indicates a different effect for the application of asymmetric mass division in different energy regions of such processes.

The microscopic optical model potential (OMP) of $\alpha$-nucleus elastic scattering based on a double-folding model (DFM) is studied. The nucleon OMPs in nuclear matter as well as the nucleon-nucleon ($\mathit{NN}$) effective interaction are calculated in the framework of the Dirac-Brueckner-Hartree-Fock (DBHF) approach, in which the density and energy dependence is parametrized by polynomial expansions. The microscopic OMP of nucleus-nucleus scattering is obtained by doubly folding the complex $\mathit{NN}$ effective interaction with respect to the densities of both projectile and target nuclei. An improved local-density approximation is adopted to take account of the finite-range correction. Renormalization factors on the real and imaginary OMP are introduced to obtain the best fit to the experimental data. A systematic analysis of ${}^4\mathrm{He}$ elastic scattering off ${}^{12}\mathrm{C}$, ${}^{16}\mathrm{O}$, ${}^{28}\mathrm{Si}$, and ${}^{40}\mathrm{Ca}$ is performed. The calculated cross sections over a wide range of incident energies and scattering angles are in good agreement with the experimental data, which confirms the applicability of this model. Moreover, for the same projectile and target, the renormalization factors are found to be almost constant at various incident energies.

Nuclear electromagnetic currents are derived in time-ordered perturbation theory within an effective-field-theory framework including explicit nucleons, Δ isobars, and pions up to one loop, or next-to-next-to-next-to-leading order (${\mathrm{N}}^3$LO). The currents obtained at next-to-next-to-leading order (${\mathrm{N}}^2$LO), i.e., ignoring loop corrections, are used in a study of neutron radiative captures on protons and deuterons at thermal energies, and of $A=2$ and 3 nuclei magnetic moments. The wave functions for $A=2$ are derived from solutions of the Schrödinger equation with the Argonne $v_{18}$ (AV18) or CD-Bonn (CDB) potentials, while those for $A=3$ are obtained with the hyperspherical-harmonics-expansion method from a realistic Hamiltonian including, in addition to the AV18 or CDB two-nucleon, a three-nucleon potential. With the strengths of the Δ-excitation currents occurring at ${\mathrm{N}}^2$LO determined to reproduce the $n\text{−}p$ cross section and isovector combination of the trinucleon magnetic moments, we find that the cross section and photon circular polarization parameter, measured in $n\text{−}d$ and $\overrightarrow{n}\text{−}d$ processes, are underpredicted by theory; for example, the cross section is underpredicted by 11–38% as the cutoff is increased from 500 to 800 MeV. A complete analysis of the results, in particular their large cutoff dependence, is presented.

The multistep direct TUL model has been extended in order to account for nuclear deformation. The new formalism was tested in calculations of neutron emission spectra from the ${}^{232}\mathrm{Th}$($n$, $\mathit{xn}$) reaction. These calculations include vibration-rotational coupled channels for the inelastic scattering to low-lying collective levels, “deformed” multistep direct (MSD) for inelastic scattering to the continuum, multistep compound, and Hauser-Feshbach with advanced treatment of the fission channel. Prompt fission neutrons were also calculated. The comparison with experimental data shows clear improvement over the “spherical” MSD calculations and JEFF-3.1 and JENDL-3.3 evaluations. Similar calculational results have been obtained of neutron emission spectra from the stable deformed nuclei ${}^{181}\mathrm{Ta}$ and ${}^{184}\mathrm{W}$.

It is possible that a system composed of up, down, and strange quarks exists as the true ground state of nuclear matter at high densities and low temperatures. This exotic plasma, called strange quark matter (SQM), seems to be even more favorable energetically if quarks are in a superconducting state, the so-called color-flavor locked state. Here we present calculations made on the basis of the MIT bag model, considering the influence of finite temperature on the allowed parameters characterizing the system for stability of bulk SQM (the so-called stability windows) and also for strangelets, small lumps of SQM, both in the color-flavor locking scenario. We compare these results with the unpaired SQM and also briefly discuss some astrophysical implications of them. Also, the issue of the strangelet's electric charge is discussed. The effects of dynamical screening, though important for nonpaired SQM strangelets, are not relevant when considering pairing among all three flavors and colors of quarks.

I present the first isolation of azimuth quadrupole components from published $v_2(p_t)$ data (called elliptic flow) as spectra on transverse rapidity $y_t$ for identified pions, kaons, and Λ's/protons from minimum-bias Au-Au collisions at 200 GeV. The form of the spectra on $y_t$ indicates that the three hadron species are emitted from a common boosted source with boost $\Delta y_{t0}~0.6$. The quadrupole spectra have a Lévy form similar to the soft component of the single-particle spectrum, but with significantly reduced ($~0.7$ times) slope parameters $T$. Comparison of quadrupole spectra with single-particle spectra suggests that the quadrupole component comprises a small fraction (<5%) of the total hadron yield, contradicting the hydrodynamic picture of a thermalized, flowing bulk medium. The form of $v_2(p_t)$ is, within a constant factor, the product of $p_t^{\text{'}}$ ($p_t$ in the boost frame) times the ratio of quadrupole spectrum to single-particle spectrum. That ratio in turn implies that above $0.5\hspace{0.5em}\mathrm{GeV}/c$, the form of $v_2(p_t)$ is dominated by the hard component of the single-particle spectrum (interpreted as being due to minijets). It is therefore unlikely that the so-called constituent-quark scaling attributed to $v_2$ is relevant to soft hadron production mechanisms (e.g., chemical freeze-out).

We analyze the decay rates ${\lambda }_{{\beta }_c^{-}}$ and ${\lambda }_{{\beta }_b^{-}}$ of the continuum- and bound-state ${\beta }^{-}$-decays for bare ${}^{205}\mathrm{Hg}$${}^{80+}$ and ${}^{207}\mathrm{Tl}$${}^{81+}$ ions. For the ratio of the decay rates $R_{b/c}={\lambda }_{{\beta }_b^{-}}/{\lambda }_{{\beta }_c^{-}}$ we obtain the values $R_{b/c}=0.161$ and $R_{b/c}=0.190$ for bare ${}^{205}\mathrm{Hg}$${}^{80+}$ and ${}^{207}\mathrm{Tl}$${}^{81+}$ ions, respectively. The theoretical value of the ratio $R_{b/c}=0.190$ for the decays of ${}^{207}\mathrm{Tl}$${}^{81+}$ agrees well with the experimental data $R_{b/c}^{\exp }=0.188(18)$, obtained at GSI. The theoretical ratio $R_{b/c}=0.161$ for ${}^{205}\mathrm{Hg}$${}^{80+}$ is about $20\%$ smaller than the experimental value $R_{b/c}^{\exp }=0.20(2)$, measured recently at GSI. We give arguments that the nuclear structure of the nuclei in the ${}^{205}\mathrm{Hg}$${}^{80+}\to$ ${}^{205}\mathrm{Tl}$${}^{81+}$ transition cannot provide such an enhancement of the ratio. We estimate the values of the continuum- and bound-state ${\beta }^{-}$-decay rates of the bare ${}^{205}\mathrm{Hg}$${}^{80+}$ ions.

The discovery of naturally occurring long-lived isomeric states ($t_{1/2}>{10}^8$ yr) in the neutron-deficient isotopes ${}^{211,213,217,218}\mathrm{Th}$ [A. Marinov et al., Phys. Rev. C 76, 021303(R) (2007)] was reexamined using accelerator mass spectrometry (AMS). Because AMS does not suffer from molecular isobaric background in the detection system, it is an extremely sensitive technique. Despite our up to two orders of magnitude higher sensitivity we cannot confirm the discoveries of neutron-deficient thorium isotopes and provide upper limits for their abundances.

The dipole response of the $N=50$ nucleus ${}^{90}\mathrm{Zr}$ was studied in photon-scattering experiments at the electron linear accelerator ELBE with bremsstrahlung produced at kinetic electron energies of 7.9, 9.0, and 13.2 MeV. We identified 189 levels up to an excitation energy of 12.9 MeV. Statistical methods were applied to estimate intensities of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. In this way we derived the photoabsorption cross section up to the neutron-separation energy. This cross section matches well the photoabsorption cross section obtained from ($\gamma$, $n$) data and thus provides information about the extension of the dipole-strength distribution toward energies below the neutron-separation energy. An enhancement of $E1$ strength has been found in the range of 6 to 11 MeV. Calculations within the framework of the quasiparticle-phonon model ascribe this strength to a vibration of the excessive neutrons against the $N=Z$ neutron-proton core, giving rise to a pygmy dipole resonance.

Nuclear pairing properties are studied within an approach that includes the quasiparticle-number fluctuation (QNF) and coupling to the quasiparticle-pair vibrations at finite temperature and angular momentum. The formalism is developed to describe noncollective rotations about the symmetry axis. The numerical calculations are performed within a doubly folded equidistant multilevel model as well as several realistic nuclei. The results obtained for the pairing gap, total energy, and heat capacity show that the QNF smoothes out the sharp SN phase transition and leads to the appearance of a thermally assisted pairing gap in rotating nuclei at finite temperature. The corrections due to the dynamic coupling to SCQRPA vibrations and particle-number projection are analyzed. The effect of backbending of the momentum of inertia as a function of squared angular velocity is also discussed.

Precise quasielastic and $\alpha$-transfer excitation functions, at ${\theta }_{\mathrm{lab}}={161}^{°}$, have been measured at energies near the Coulomb barrier for the ${}^{16}\mathrm{O}$ $+$ ${}^{63}\mathrm{Cu}$ system. This is the first time reported quasielastic barrier distribution for a medium odd-$A$ nucleus target deduced from the data. Additional elastic scattering angular distributions data available in the literature for this system were also used in the investigation of the role of several individual channels in the reaction dynamics, by comparing the data with free-parameter coupled-channels calculations. In order to do so, the nucleus-nucleus bare potential has a double-folding potential as the real component and only a very short-range imaginary potential. The quasielastic barrier distribution has been shown to be a powerful tool in this analysis at the barrier region. A high collectivity of the ${}^{63}\mathrm{Cu}$ was observed, mainly due to the strong influence of its $5/2^{-}$ and $7/2^{-}$ states on all reaction channels investigated. A striking influence of the reorientation of the ground-state target-spin on the elastic cross sections, taken at backward angles, was also observed.

The jet quenching parameter $\widehat{q}$ is analyzed for a quark jet propagating in an anisotropic plasma. The momentum anisotropy is calculated at high temperature of the underlying quark-gluon plasma. $\widehat{q}$ is explicitly estimated in leading-logarithmic approximation by the broadening of the massless quark interacting via gluon exchange. A plasma instability is present. Strong indications are found that $\widehat{q}$ is increasing with increasing anisotropy. Possible implications for the saturation scale $Q_s$ in $A\text{−}A$ collisions are pointed out.

The four proton-hole nucleus ${}^{204}\mathrm{Pt}$ was populated in the fragmentation of an $E/A=1$ GeV ${}^{208}\mathrm{Pb}$ beam. The yrast structure of ${}^{204}\mathrm{Pt}$ has been observed up to angular momentum $I=10\hslash$ by detecting delayed $\gamma$-ray transitions originating from metastable states. These long-lived excited states have been identified to have spin-parities of $I^{\pi }=({10}^{+})$, $(7^{-})$, and $(5^{-})$ and half-lives of $T_{1/2}=146(14)\hspace{0.5em}\mathit{ns}$, $55(3)\mu$s, and $5.5(7)\mu$s, respectively. The structure of the magic $N=126$ ${}^{204}\mathrm{Pt}$ nucleus is discussed and understood in terms of the spherical shell model. The data suggest a revision of the two-body interaction for $N=126$, $Z<82$, which determines the evolution of nuclear structure toward the r-process waiting point nuclei.

The structure of neutron-rich Cr isotopes is systematically investigated by using the spherical shell model. The calculations reproduce well the known energy levels for the even-even ${}^{52-62}\mathrm{Cr}$ and odd-mass ${}^{53-59}\mathrm{Cr}$ nuclei, and predict a lowering of excitation energies around neutron number $N=40$. The calculated $B(E2;2_1^{+}\to 0_1^{+})$ systematics shows a pronounced collectivity around $N=40$; a similar characteristic behavior has been suggested for Zn and Ge isotopes. Causes for the sudden drop of the $9/2_1^{+}$ energy in ${}^{59}\mathrm{Cr}$ and the appearance of very low $0_2^{+}$ states around $N=40$ are discussed. We also predict a new band with strong collectivity built on the $0_2^{+}$ state in the $N=40$ isotope ${}^{64}\mathrm{Cr}$.

The time delays in fission induced by bombardment of W with 180 MeV ${}^{32}\mathrm{S}$, $240\text{−}255$ MeV ${}^{48}\mathrm{Ti}$, $330\text{−}375$ MeV ${}^{58}\mathrm{Ni}$, and 390 MeV ${}^{74}\mathrm{Ge}$ have been measured by observation of crystal blocking. Nearly all results are consistent with exponential decay with lifetimes of order ${10}^{-18}$ s which depend weakly on the atomic number of the composite nucleus. This is inconsistent with the Bohr-Wheeler model of fission from a compound nucleus in statistical equilibrium at each stage in a neutron evaporation cascade and supports a picture of strongly damped quasifission. A simple diffusion model with one-body dissipation reproduces roughly the observed time scale and the exponential decay. It suggests that the outer fission barrier could play a significant role in the observed, very slow decays.