The validity of the surrogate ratio method for determining ($n,f$) cross sections for actinide nuclei is examined. This method relates the ratio of two compound-nucleus reaction cross sections to a ratio of coincidence events from two measurements in which the same compound nuclei are formed via a direct reaction. With certain assumptions, the method allows one of the cross sections to be inferred if the other is known. We develop a nuclear reaction-model simulation to investigate whether the assumptions underlying the ratio approach are valid and employ these simulations to assess whether the cross sections obtained indirectly by applying a ratio analysis agree with the expected results. In particular, we simulate surrogate experiments that allow us to determine fission cross sections for selected actinide nuclei. The nuclei studied, ${}^{233}\mathrm{U}$ and ${}^{235}\mathrm{U}$, are very similar to those considered in recent surrogate experiments. We find that in favorable cases the ratio method provides useful estimates of the desired cross sections, and we discuss some of the limitations of the approach.

The strong $K^{-}p$ scattering length is extracted within chiral SU(3) unitary approaches from a very large variety of fits to low-energy $K^{-}p$ scattering data. Very good overall agreement with available scattering data is obtained and the resulting scattering length is compared with the new accurate kaonic hydrogen data from DEAR. The pole structures of the obtained fits to experiment are critically examined.

By considering the $x$-dependence of ${\pi }^{+},{\pi }^{-},K^{+},K^{-},\Lambda ,\overline{\Lambda },p,\overline{p}$ hadron productions in charged lepton semi-inclusive deep-inelastic scattering off nuclear target (using Fe as an example) and deuteron D target, we find that $({\overline{\Lambda }}^A/{\Lambda }^A)/({\overline{\Lambda }}^D/{\Lambda }^D)$ and $({\overline{p}}^A/p^A)/({\overline{p}}^A/p^A)$ are ideal to figure out the nuclear sea content, which is predicted to be different by different models accounting for the nuclear EMC effect.

The $S$-matrix approach is used to calculate both charged- and neutral-pion production in nucleon-nucleon ($\mathit{NN}$) scattering near threshold. The irreducible pion-rescattering diagram, direct production mechanism, Δ isobars in intermediate states, and $Z$ diagrams mediated by heavy isoscalar mesons are included in the calculation. For the $\mathit{NN}$ distortions, we considered a realistic interaction, within the Bonn family of potentials, which describes the nucleonic inelasticities above the pion production energy threshold.

We study the effect of the splitting of neutron and proton effective masses with isospin asymmetry on the properties of the Skyrme energy density functional. We discuss the ability of the latter to predict observables of infinite matter and finite nuclei, paying particular attention to controlling the agreement with ab initio predictions of the spin-isospin content of the nuclear equation of state, as well as diagnosing the onset of finite size instabilities, which we find to be of critical importance. We show that these various constraints cannot be simultaneously fulfilled by the standard Skyrme force, calling at least for an extension of its $P$-wave part.

We present a set of new deuteron global phenomenological optical model potential parameters for nuclides in the mass range $12⩽A⩽209$ with incident energies from threshold up to 200 MeV, based on the experimental data of deuteron total reaction cross sections and elastic scattering angular distributions. The extracted deuteron global optical model potential parameters are compared to existing deuteron global optical potential.

The cross section for inelastic scattering of Borromean halo nuclei from protons is evaluated using the Multiple Scattering expansion of the Total transition amplitude (MST) formalism. Differential cross sections and energy spectra are shown for $p$-${}^6\mathrm{He}$ at 700 MeV/nucleon. The role of spin flip excitations is analyzed.

It is shown that a quantum chromodynamics-based nuclear absorption model, with few parameters fixed to reproduce experimental $J/\psi$ yield in 200 GeV proton-proton/proton-nucleon and 450 GeV proton-nucleon collisions, can explain the preliminary PHENIX data on the centrality dependence of $J/\psi$ suppression in Cu+Cu collisions at Relativistic Heavy Ion Collider (RHIC) energy, $\sqrt{s_{\mathit{NN}}}=200$ GeV. However, the model does not give a satisfactory description for the preliminary PHENIX data on the centrality dependence of $J/\psi$ suppression in Au+Au collisions. The analysis suggests that in Au+Au collisions, $J/\psi$ are suppressed in a medium unlike the medium produced in CERN Super Proton Synchrotron energy nuclear collisions or in RHIC energy Cu+Cu collisions.

We propose a model for the description of strongly interacting quarks and gluon quasiparticles at $T=(1-3)T_c$ as a classical and nonrelativistic colored Coulomb gas. The sign and strength of the interparticle interactions are fixed by the scalar product of their classical color vectors subject to Wong's equations. The model displays a number of phases as the Coulomb coupling is increased ranging from a gas, to a liquid, to a crystal with antiferromagnetic-like color ordering. We analyze the model using molecular dynamics simulations and discuss the density-density correlator in real time. We extract pertinent decorrelation times, diffusion, and viscosity constants for all phases. The classical results when extrapolated to the strongly coupled quark-gluon plasma suggest that the phase is liquid-like, with a diffusion constant $D\approx 0.1/T$ and a shear viscosity to entropy density ratio $\eta /s\approx 1/3$.

We analyze the screening and bulk energy of a classical and strongly interacting plasma of color charges, a model we recently introduced for the description of a quark-gluon plasma at $T=(1-3)T_c$. The partition function is organized around the Debye-Hückel limit. The linear Debye-Hückel limit is corrected by a virial expansion. For the pressure, the expansion is badly convergent even in the dilute limit. The nonlinear Debye-Hückel theory is studied numerically as an alternative for moderately strong plasmas. We use the Debye theory of solid to extend the analysis to the crystal phase at very strong coupling. The analytical results for the bulk energy per particle compare well with the numerical results from molecular dynamics simulations for all couplings.

We present the first study of the β decay of ${}^{23}\mathrm{Al}$ undertaken with pure samples. The study was motivated by nuclear astrophysics questions. Pure samples of ${}^{23}\mathrm{Al}$ were obtained from the momentum achromat recoil separator (MARS) of Texas A&M University, collected on a fast tape-transport system, and moved to a shielded location where β and β-γ coincidence measurements were made. We deduced β branching ratios and log $\mathit{ft}$ values for transitions to states in ${}^{23}\mathrm{Mg}$, and from them determined unambiguously the spin and parity of the ${}^{23}\mathrm{Al}$ ground state to be $J^{\pi }=5/2^{+}$. We discuss how this excludes the large increases in the radiative proton capture cross section for the reaction ${}^{22}\mathrm{Mg}(p,\gamma ){}^{23}\mathrm{Al}$ at astrophysical energies, which were implied by claims that the spin and parity is $J^{\pi }=1/2^{+}$. The log $\mathit{ft}$ for the Fermi transition to its isobaric analog state (IAS) in ${}^{23}\mathrm{Mg}$ is also determined for the first time. This IAS and a state 16 keV below it are observed, well separated in the same experiment for the first time. We can now solve a number of inconsistencies in the literature, exclude strong isospin mixing claimed before, and obtain a new determination of the resonance strength. Both states are resonances in the ${}^{22}\mathrm{Na}$($p,\gamma$)${}^{23}\mathrm{Mg}$ reaction at energies important in novae. The reactions ${}^{22}\mathrm{Mg}(p,\gamma ){}^{23}\mathrm{Al}$ and ${}^{22}\mathrm{Na}(p,\gamma ){}^{23}\mathrm{Mg}$ have both been suggested as possible candidates for diverting some of the flux in oxygen-neon novae explosions from the $A=22$ into the $A=23$ mass chain.

The nuclear spin-lattice relaxation of ${}^{62}\mathrm{Cu}$ in iron has been studied with the low temperature nuclear orientation method. At temperatures ranging from 6.5 mK to about 100 mK and a magnetic field of 0.1 $T$ the relaxation constant for ${}^{62}\mathrm{Cu}$ in Fe was found to be $C_{\mathrm{K}}[$${}^{62}\mathrm{Cu}$$]=4.34(25)\mathrm{s}\mathrm{K}$.

A systematic study of the inclusive ($0\nu +2\nu$) double beta ($\beta \beta$) decay of ${}^{100}\mathrm{Mo}$ to various excited final states of ${}^{100}\mathrm{Ru}$ was performed. Utilizing two large HPGe detectors operated in coincidence, a search for the subsequent deexcitation $\gamma \gamma$ cascades was conducted. A 1.05-kg sample of isotopically enriched $(98.4\%)$${}^{100}\mathrm{Mo}$ was investigated for 455 days, yielding an unambiguous observation of the $\beta \beta$ decay of ${}^{100}\mathrm{Mo}$ to the $0_1^{+}$ state (1130.3 keV) of ${}^{100}\mathrm{Ru}$. This excited final state decays via the $0_1^{+}\to 2_1^{+}\to 0_{\mathrm{gs}}^{+}$ sequence (with $E_{\gamma 1}=590.8$ keV and $E_{\gamma 2}=539.5$ keV), and 22 such coincidence events were detected, with a continuous background estimated to be 2.5 events. This counting rate corresponds to a decay half-life for the $\beta \beta (0^{+}\to 0_1^{+})$ transition of $T_{1/2}^{(0\nu +2\nu )}=[6.0_{-1.1}^{+1.9}(\mathrm{stat})\pm 0.6(\mathrm{syst})]\times {10}^{20}$ years. Lower limits on decay half-lives were achieved for higher excited final states.

Neutron total cross-section measurements on ${}^{54}\mathrm{Cr}$ up to a neutron energy of 2 MeV have been analyzed to deduce resonance parameters as well as spins and parities. Neutron strength functions have been deduced, based on data in the energy range 20–1000 keV, for $s$-, $p$-, and $d$-wave interactions and, in units of (${10}^{-4}$), are $2.8\pm 0.9$, $0.23\pm 0.06$, and $4.4\pm 0.7$, respectively. Corresponding level densities in units of ${\mathrm{keV}}^{-1}$are $0.025\pm 0.003$, $0.032\pm 0.003$, and $0.107\pm 0.006$, respectively. The distribution of nearest-neighbor spacings for $s$ waves has been compared to Poisson and Wigner predictions for both ${}^{54}\mathrm{Cr}$ and ${}^{52}\mathrm{Cr}$. Hints are seen of greater chaotic behavior in the case of the closed-neutron-shell ${}^{52}\mathrm{Cr}$ and of regular dynamics for ${}^{54}\mathrm{Cr}$, suggestive of changes in chaoticity of nuclear dynamics with shell closure.

The hadronization scheme for parton transport in relativistic heavy ion collisions is considered in detail. It is pointed out that the traditional scheme for particles being freezed out one by one leads to serious problem on unreasonable long lifetime of partons. A collective phase transition following a supercooling is implemented in a simple way. It turns out that the modified model with a sudden phase transition is able to reproduce the experimental longitudinal distributions of final state particles better than the original one does. The encouraging results indicate that equilibrium phase transition should be taken into proper account in parton transport models for relativistic heavy ion collisions.

We propose a new approach in QCD sum rules applied for exotic hadrons with a number of quarks, exemplifying the pentaquark ${\Theta }^{+}(I=0,J=1/2)$ in the Borel sum rule. Our approach enables reliable extraction of the pentaquark properties from the sum rule with good stability in a remarkably wide Borel window. The appearance of its valid window originates from a favorable setup of the correlation functions with the aid of chirality of the interpolating fields on the analogy of the Weinberg sum rule for the vector currents. Our setup leads to large suppression of the continuum contributions which have spoiled the Borel stability in the previous analyses, and consequently enhances importance of the higher-dimensional contributions of the OPE, which are indispensable for investigating the pentaquark properties. Implementing the OPE analysis up to dimension 15, we find that the sum rules for the chiral-even and odd parts independently give the ${\Theta }^{+}$ mass of $1.68\pm 0.22$ GeV with uncertainties of the condensate values. Our sum rule indeed gives rather flat Borel curves almost independent of the continuum thresholds both for the mass and pole residue. Finally, we also discuss possible isolation of the observed states from the $\mathit{KN}$ scattering state on view of chiral symmetry.

The symmetry energy of nucleonic matter is usually assumed to be quadratic in the isospin density. While this may be justified at subsaturation densities, there is no need to enforce this restriction at supersaturation densities. The presence of a quartic term can strongly modify the critical density for the direct Urca process which leads to faster cooling of neutron stars. Neutron star cooling predictions which lie below the observational data can, for some equations of state, be repaired with a quartic term which effectively turns off the direct Urca process.

In medium $T$-matrix calculations for symmetric nuclear matter at zero and finite temperatures are presented. The internal energy is calculated from the Galitskii-Koltun's sum rule and from the summation of the diagrams for the interaction energy. The pressure at finite temperature is obtained from the generating functional form of the thermodynamic potential. The entropy at high temperature is estimated and compared to expressions corresponding to a quasiparticle gas.

Statistical model analysis of the measured evaporation residue and fission excitation functions indicates the presence of shell corrections to the liquid drop energy at the saddle point deformations for nuclei of mass $~200$, if one attempts to fit simultaneously the measured prefission neutron multiplicities.

The photoproduction of $K^0$ on the deuteron has been investigated with the inclusion of the $\mathit{YN}$ and $\mathit{KN}$ final-state interaction (FSI), as well as the pion-mediated process $\gamma d\to \pi \mathit{NN}\to \mathit{KYN}$. The $\mathit{YN}$ rescattering effects for the inclusive cross section are found to be large in the threshold regions. Polarization observables show sizable FSI effects at larger kaon and hyperon angles. It is shown that the extraction of the elementary $\gamma N\to \mathit{KY}$ amplitude is possible in the quasifree scattering region where FSI effects are negligible. Furthermore, the cross sections in this region are large, indicating that measurements in this kinematic region are favored.