The structure functions of the nucleus in the cumulative region of $x>\mathrm{}1\mathrm{}$ are studied in terms of nucleon degrees of freedom. At high $Q^2$ the resulting expressions are presented as a sum of contributions from few-nucleon correlations. Two-nucleon correlations are studied in detail. Spin variables are averaged out. In the region $1<x<\mathrm{}2\mathrm{}$ the structure functions are calculated using the relativistic interaction proposed by Gross et al. They are found to fall with x faster than an exponential. For carbon at $x=1.05,$ where the method is not rigorously applicable, they turn out to be roughly 2 times larger than the experimental data.

The $\beta$-decay rates of neutron-rich nuclei relevant to the r-process nucleosynthesis are mostly beyond experimental reach. Their predictions demand a self-consistent extrapolation of various nuclear properties away from the experimentally known regions. The allowed transitions approximation commonly used in large-scale microscopic calculations also needs to be revised in different mass regions. The density functional+continuum QRPA approximation to self-consistent calculations of the ground state properties, Gamow-Teller and first-forbidden $\beta$-decay transitions of nuclei far from stability is developed. Systematic calculations are performed of the allowed and first-forbidden $\beta$-decay rates for the r-process relevant nuclides near the closed neutron shells at $N=50,82,126.\mathrm{}$ The importance of first-forbidden decays near $Z>~50,N\approx 82$ and near $N=126\mathrm{}$ is shown. The total $\beta$-decay half-lives in the region “east” of the ${}^{208}\mathrm{Pb}$ are estimated. A comparison with recent experimental data, global calculations, and self-consistent microscopic predictions is presented.

We calculate the imaginary part of the induced pseudoscalar form factor of the nucleon $G_P\mathrm{}\left(t\right)\mathrm{}$ in the framework of two-loop heavy baryon chiral perturbation theory. The effect of the calculated three-pion continuum on the pseudoscalar constant $g_P{=(m}_{\mu }{/2M)G}_P(t=-{0.877m}_{\mu }^2),$ measurable in ordinary muon capture ${\mu }^{-}\overrightarrow{p}{\nu }_{\mu }n,$ turns out to be negligibly small. Possible contributions from counterterms at two-loop order are numerically smaller than the uncertainty of the dominant pion-pole term proportional to the pion-nucleon coupling constant $g_{\pi N}=13.2\mathrm{}\pm \mathrm{0.2.}$ We conclude that a sufficiently accurate representation of the induced pseudoscalar form factor of the nucleon at low momentum transfers t is given by the sum of the pion-pole term and the Adler-Dothan-Wolfenstein term: $G_P{\mathrm{}\left(t\right)=4g}_{\pi N}{\mathrm{Mf}}_{\pi }{/(m}_{\pi }^2-t)-{2g}_A{M}^2〈r_A^2〉/3,$ with $〈r_A^2〉=(0.44\mathrm{}\pm 0.02){\mathrm{fm}}^2$ the axial mean square radius of the nucleon.

The ratios of charged antiparticles to particles have been obtained for pions, kaons, and protons near midrapidity in central Au+Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=200\mathrm{}$ GeV. Ratios of $〈{\pi }^{-}〉/〈{\pi }^{+}〉=1.025\mathrm{}\pm 0.006\mathrm{}(\mathrm{stat}.\mathrm{})\mathrm{}\pm 0.018\mathrm{}(\mathrm{syst}.\mathrm{})\mathrm{},〈K^{-}〉/〈K^{+}〉=0.95\mathrm{}\pm 0.03\mathrm{}(\mathrm{stat}.\mathrm{})\mathrm{}\pm 0.03\mathrm{}(\mathrm{syst}.\mathrm{})\mathrm{},$ and $〈\overline{p}〉/〈p〉=0.73\mathrm{}\pm 0.02\mathrm{}(\mathrm{stat}.\mathrm{})\mathrm{}\pm 0.03\mathrm{}(\mathrm{syst}.\mathrm{})\mathrm{}$ have been observed. The $〈K^{-}〉/〈K^{+}〉$ and $〈\overline{p}〉/〈p〉$ ratios are consistent with a baryochemical potential ${\mu }_B$ of 27 MeV, roughly a factor of 2 smaller than in $\sqrt{s_{{}_{\mathrm{NN}}}}=130\mathrm{}$ GeV collisions. The data are compared to results from lower energies and model calculations. Our accurate measurements of the particle ratios impose stringent constraints on current and future models dealing with baryon production and transport.

The structure of the particle unbound nucleus ${}^{10}\mathrm{Li}$ was investigated in a kinematically complete experiment using the ${}^9\mathrm{Li}{\mathrm{}(d,p)\mathrm{}}^{10}\mathrm{Li}$ reaction in inverse kinematics at an incident ${}^9\mathrm{Li}$ energy of 20 MeV/nucleon. The experiment utilized the S800 Spectrograph at the National Superconducting Cyclotron Laboratory to measure the outgoing ${}^9\mathrm{Li}$ from the breakup of ${}^{10}\mathrm{Li}$ in coincidence with the recoiling protons from the $\mathrm{}(d,p)\mathrm{}$ reaction which were measured using an array of silicon detectors. Based on the kinematics of the recoiling protons from the ${}^9\mathrm{Li}\mathrm{}(d,p)\mathrm{}$ reaction, we measured a lower limit of $\Delta =33.10\mathrm{}\pm 0.08$ MeV (i.e., $\Delta >33.02\mathrm{}$ MeV) for the mass excess of ${}^{10}\mathrm{Li}$ which is consistent with previous measurements. Through the complete reconstruction of the breakup kinematics, the structure of ${}^{10}\mathrm{Li}$ associated with a ground state ${}^9\mathrm{Li}$ core was distinguishable from structure associated with a ${}^9\mathrm{Li}$ core in its first excited state. The observed ratio of ${}^9{\mathrm{Li}}^{*}$ core events to the total number of ${}^{10}\mathrm{Li}$ events that were detected in the experiment was $0.10\pm 0.04$ at forward center of mass angles $(2.7\mathrm{}°$ to $9.5°),$ and $0.24\pm 0.03$ at more backward center of mass angles $(11\mathrm{}°$ to $26°).\mathrm{}$ The resulting Q-value spectra was best fit with either a single resonance located at $Q=-2.58\left(11\right)\mathrm{}$ MeV [corresponding to a neutron separation energy $S_n=-0.35\left(11\right)\mathrm{}$ MeV] or two resonances located at $Q=-3.00\left(24\right)\mathrm{}$ MeV $[S_n=-0.77(24)\mathrm{}$ MeV] and $Q>\mathrm{}-2.43$ MeV ${(S}_n>-0.2$ MeV).

Energy distributions of neutrons emitted from thick targets of ${}^{27}\mathrm{Al}$ and ${}^{46}\mathrm{Ti}$ are measured for alpha induced reactions at 30, 40, and 50 MeV projectile energies. Measurements are done at $0°,30°,$ and $45°$ with respect to the projectile direction using the proton recoil scintillation technique. The measured data are compared with results from calculations using three different approaches of the exciton model namely, the master equation, the closed form and the hybrid model (a variant of the exciton model). The corresponding nuclear reaction model codes used for the purpose are PEQAG [E. Betak and J. Dobes, Report No. IP EPRC SAS 43/(1983), Bratislava, 1983], PRECO-D2, [C. Kalbach, Report No. LA-10248-MS, Los Alamos National Laboratory, Los Alamos, 1985] and ALICE91 [M. Blann, Lawrence Livermore National Laboratory Report No. UCID 19614, 1982], respectively. Proton induced neutron yield distributions measured by others are also included in the comparison. The calculated results from the hybrid model code ALICE91 give overall close approximations of the measured data compared to the other models.

We analyze the Sudbury Neutrino Observatory (SNO) and Super-Kamiokande (SK) data on charged current (CC), neutral current (NC), and neutrino electron elastic scattering reactions to constrain the leading weak axial two-body current parametrized by $L_{1,A}.$ This two-body current is the dominant uncertainty of every low-energy weak interaction deuteron breakup process, including SNO’s CC and NC reactions. Our method shows that the theoretical inputs to SNO’s determination of the CC and NC fluxes can be self-calibrated, be calibrated by SK, or be calibrated by reactor data. The only assumption made is that the total flux of active neutrinos has the standard ${}^8\mathrm{B}$ spectral shape (but distortions in the electron neutrino spectrum are allowed). We show that SNO’s conclusion about the inconsistency of the no-flavor-conversion hypothesis does not contain significant theoretical uncertainty, and we determine the magnitude of the active solar neutrino flux.

Excited low-spin states in ${}^{94}\mathrm{Mo}$ have been studied extensively with a combination of $\gamma$-ray spectroscopic techniques. We have performed photon scattering experiments, $\gamma \gamma$ coincidence measurements following the ${\beta }^{+}$ decay of ${}^{94}{\mathrm{Tc}}^{\mathrm{m}},$ in-beam $\gamma \gamma$ coincidence studies with the reaction ${}^{91}\mathrm{Zr}(\alpha {,n)}^{94}\mathrm{Mo},$ and ${}^{94}\mathrm{Mo}{(n,n}^{\prime }\gamma )$ measurements. These experiments yielded detailed information about the low-spin level scheme of ${}^{94}\mathrm{Mo}.$ From measured lifetimes, branching ratios, and multipole mixing ratios, many absolute transition strengths were determined. These data permitted the interpretation of several low-spin states in terms of collective excitations, that are not fully symmetric with respect to the proton-neutron degree of freedom, the so-called mixed-symmetry (MS) states: The one-phonon $2^{+}$ MS state and three members of an expected multiplet of two-phonon MS states were identified from absolute $M1\mathrm{}$ and $E2\mathrm{}$ transition strengths. The data also enable us to identify several proton-neutron-symmetric multiphonon states.

We investigate the nucleon-nucleon interaction by using the meson exchange model and the two-body Dirac equations of constraint dynamics. This approach to the two-body problem has been successfully tested for QED and QCD relativistic bound states. An important question we wish to address is whether or not the two-body nucleon-nucleon scattering problem can be reasonably described in this approach as well. This test involves a number of related problems. First we must reduce our two-body Dirac equations exactly to a Schrödinger-like equation in such a way that allows us to use techniques to solve them already developed for Schrödinger-like systems in nonrelativistic quantum mechanics. Related to this, we present a new derivation of Calogero’s variable phase shift differential equation for coupled Schrödinger-like equations. Then we determine if the use of nine meson exchanges in our equations gives a reasonable fit to the experimental scattering phase shifts for $n-p$ scattering. The data involve seven angular momentum states including the singlet states ${}^1{S}_0,$ ${}^1{P}_1,$ ${}^1{D}_2$ and the triplet states ${}^3{P}_0,$ ${}^3{P}_1,$ ${}^3{S}_1,$ ${}^3{D}_1.$ Two models that we have tested give us a fairly good fit. The parameters obtained by fitting the $n-p$ experimental scattering phase shift give a fairly good prediction for most of the $p-p$ experimental scattering phase shifts examined (for the singlet states ${}^1{S}_0,$ ${}^1{D}_2$ and triplet states ${}^3{P}_0,$ ${}^3{P}_1).\mathrm{}$ Thus the two-body Dirac equations of constraint dynamics present us with a fit that encourages the exploration of a more realistic model. We outline generalizations of the meson exchange model for invariant potentials that may possibly improve the fit.

A comprehensive high-spin decay scheme has been deduced for ${}^{57}\mathrm{Co}$ using the Gammasphere Germanium detector array coupled to the $4\pi$ charged-particle detector system Microball. Following the fusion-evaporation reaction of ${}^{28}\mathrm{Si}{(}^{36}\mathrm{Ar},1\mathrm{}\alpha {3p)}^{57}\mathrm{Co}$ at 136 MeV beam energy about 90 excited states have been observed in ${}^{57}\mathrm{Co},$ which are connected by some 230 $\gamma -\mathrm{r}\mathrm{a}\mathrm{y}$ transitions. The proposed level scheme reaches 16 MeV excitation energy at a spin of $17ħ–18ħ.$ With its complexity the level scheme of ${}^{57}\mathrm{Co}$ appears to be “complete” up to 1 or 2 MeV above the yrast line. This aspect is further investigated through a comparison of the data with spherical shell-model calculations.

A three-configuration mixing calculation is performed in the context of the interacting boson model with the aim to describe recently observed collective bands built on low-lying $0^{+}$ states in neutron-deficient lead isotopes. The configurations that are included correspond to the regular, spherical states as well as two-particle two-hole and four-particle four-hole excitations across the $Z=82\mathrm{}$ shell gap.

Using a semiclassical mean field theory, we show that the screening potential exhibits a characteristic radial variation in the tunneling region in sharp contrast to the assumption of the constant shift in all previous works. Also, we show that the explicit treatment of the tunneling region gives a larger screening energy than that in the conventional approach, which studies the time evolution only in the classical region and estimates the screening energy from the screening potential at the external classical turning point. This modification becomes important if the electronic state is not a single adiabatic state at the external turning point either by pretunneling transitions of the electronic state or by the symmetry of the system even if there is no essential change with the electronic state in the tunneling region.

Effects of resonant single-particle (s.p.) states on the pairing correlations are investigated by an exact treatment of the pairing Hamiltonian on the Gamow shell model basis. We introduce the s.p. states with complex energies into the Richardson equations. The solution shows the property that the resonant s.p. states with large widths are less occupied. The importance of many-body correlations between bound and resonant particle pairs is shown.

We investigate the consequences of possible medium modifications of the $\phi$ meson at finite nuclear matter density on the $K^{+}{K}^{-}$ mass distribution in photonuclear reactions. The inclusive cross sections for $K^{+}{K}^{-}$ pair production are calculated within a semiclassical Boltzmann-Uehling-Uhlenback (BUU) transport model, which combines the initial-state interaction of the incoming photon with the final-state interactions of the produced particles. The effects of final-state interactions on the invariant mass distribution of the observed $K^{+}{K}^{-}$ pairs are discussed in detail. In addition, we calculate the Coulomb correction and possible effects of hadronic kaon potentials on the $K^{+}{K}^{-}$ mass spectrum. Due to the large cross sections for reactions of the final-state particles with the surrounding nuclear medium and the influence of the Coulomb potential, we find no measurable sensitivity of the observables to the $\phi$ properties at finite baryon density.

The decay of on-line mass-separated ${}^{114}\mathrm{Rh}$ has been studied by $\gamma$ spectroscopy. A definite odd parity and a probable $I=7\mathrm{}$ are deduced for the high-spin $\beta$-decaying level. The 1116 keV and 1392 keV levels in the ${}^{114}\mathrm{Pd}$ daughter nucleus are candidates for the bottom of the $\beta$ band. There is no support for a previously reported very-low-lying $0^{+}$ level at 871 keV. A $K=4\mathrm{}$ band built on the new level at 1639 keV is proposed. The lowest-lying two-quasiparticle levels in ${}^{114}\mathrm{Pd}$ are calculated in the framework of the quantum Monte Carlo pairing model using deformed shell model states. The lowest configurations are associated with an oblate minimum of the potential energy.

Extensions to the yrast decay sequence of the neutron-rich nucleus ${}_{17}^{41}{\mathrm{Cl}}_{24}$ have been established through the analysis of the $\gamma$ deexcitation of fragments produced in deep-inelastic processes which occur when 230 MeV ${}^{36}\mathrm{S}$ ions interact with a target of ${}^{176}\mathrm{Yb}.$ The highly sensitive GASP array of escape-suppressed Ge detectors was used to measure the resulting $\gamma$-ray deexcitations of both projectilelike and targetlike fragments. New excited states in ${}^{41}\mathrm{Cl}$ are observed at 1445 and 2451 keV, thus adding to the two previously known excited states. Comparisons to shell-model calculations have also been made.

By using the updated improved quantum molecular dynamics model in which a surface-symmetry potential term has been introduced, the excitation functions for fusion reactions of ${}^{40,48}\mathrm{Ca}{+}^{90,96}\mathrm{Zr}$ at energies around the Coulomb barrier have been studied. The experimental data of the fusion cross sections for ${}^{40}\mathrm{Ca}{+}^{90,96}\mathrm{Zr}$ have been reproduced remarkably well without introducing any new parameters. The fusion cross sections for the neutron-rich fusion reactions of ${}^{48}\mathrm{Ca}{+}^{90,96}\mathrm{Zr}$ around the Coulomb barrier are predicted to be enhanced compared with a non-neutron-rich fusion reaction. In order to clarify the mechanism of the enhancement of the fusion cross sections for neutron-rich nuclear fusions, we pay great attention to studying the dynamic lowering of the Coulomb barrier during a neck formation. The isospin effect on the barrier lowering is investigated. It is interesting that the effect of the projectile and target nuclear structure on fusion dynamics can be revealed to a certain extent in our approach. The time evolution of the $N/Z$ ratio at the neck region has been firstly illustrated. A large enhancement of the $N/Z$ ratio at neck region for neutron-rich nuclear fusion reactions is found.

A comparison is made between a typical intranuclear cascade (INC) model and the experimental inclusive slow $(T<\mathrm{}0.4\mathrm{}\mathrm{GeV})$ and fast $(T>\mathrm{}0.4\mathrm{}\mathrm{GeV})$ proton spectra in the p-C, C-C, and C-Ta in interactions at $3.3A\mathrm{GeV}$ over a broad angular interval from $0°$ to $180°.$ It is found that the INC model reproduces rather well the inclusive slow and fast proton spectra, provided that the mean number of interacting protons (participants) in the corresponding angular interval does not exceed 2. The systematic discrepancies are identified and shown to correspond mainly to the noncovariant nature of the INC calculations.

High-energy $\gamma$ rays in the energy range of $\sim 4–35\mathrm{MeV}$ were measured in coincidence with a $\gamma$-ray multiplicity detector array in the reaction ${}^{28}\mathrm{Si}{+}^{58}\mathrm{Ni}$ at ${E(}^{28}\mathrm{Si})=100\mathrm{}$ and 125 MeV. The data were analyzed using the statistical model, and the giant dipole resonance parameters were extracted for various multiplicity windows. The exclusive temperature dependence of the $\gamma$-ray strength function has been obtained for a wide range of angular momentum, while the angular momentum dependence has been derived over a restricted range of temperature. The observed increase in the resonance width can be attributed to an increase in temperature. No dependence on angular momentum is observed. The last observation is at variance with the results in the tin region for similar rotational frequencies.

The reaction ${p(e,e}^{\prime }{\pi }^{+}{)X}^0$ was studied with two high-resolution magnetic spectrometers to search for narrow baryon resonances. A missing mass resolution of 2.0 MeV was achieved. A search for structures in the mass region of $0.97<\mathrm{}{M}_{X^0}<1.06\mathrm{}$ GeV yielded no significant signal. The yield ratio of ${p(e,e}^{\prime }{\pi }^{+}{)X}^0{/p(e,e}^{\prime }{\pi }^{+})n$ was determined to be $(-0.35\pm 0.35)\times {10}^{-3}$ at 1.004 GeV and $(0.34\mathrm{}\pm 0.42)\times {10}^{-3}$ at 1.044 GeV. This measurement clearly demonstrated the potential of high-resolution missing mass searches in coincidence experiments.