The neutron capture cross sections of ${}^{170}\mathrm{Yb},$ ${}^{171}\mathrm{Yb},$ ${}^{172}\mathrm{Yb},$ ${}^{173}\mathrm{Yb},$ ${}^{174}\mathrm{Yb},$ and ${}^{176}\mathrm{Yb}$ have been measured in the energy range from 3 to 225 keV relative to the gold standard. Neutrons were produced at the Karlsruhe 3.75 MV Van de Graaff Accelerator via the ${}^7\mathrm{Li}{\mathrm{}(p,n)\mathrm{}}^7\mathrm{Be}$ reaction by bombarding metallic Li targets with a pulsed proton beam, and capture events were registered with the Karlsruhe $4\pi$ Barium Fluoride Detector. Neutron capture in the even ytterbium isotopes is characterized by a strong population of isomeric states, leading to unrecognized systematic uncertainties in previous measurements. For the first time, partial cross sections to ground and isomeric states could be experimentally identified in neutron time-of-flight measurements for ${}^{172}\mathrm{Yb},$ ${}^{173}\mathrm{Yb},$ ${}^{174}\mathrm{Yb},$ and ${}^{176}\mathrm{Yb}.$ The present overall uncertainties of (1–1.5) % correspond to an improvement by factors of 4–10 compared to existing data. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between $kT=8\mathrm{}$ keV and 100 keV. In four cases, the results differ by more than 15% from recent evaluations. The s-process analyses based on the present data provide further evidence in favor of stellar models for thermally pulsing low-mass asymptotic giant branch stars.

Single-particle resonance parameters and wave functions in spherical and deformed nuclei are determined through analytic continuation in the potential strength. In this method, the analyticity of the eigenvalues and eigenfunctions of the Schrödinger equation with respect to the coupling strength is exploited to analytically continue the bound-state solutions into the positive-energy region by means of Padé approximants of the second kind. The method is here applied to single-particle wave functions of the ${}^{154}\mathrm{Sm}$ and ${}^{131}\mathrm{Eu}$ nuclei. A comparison of the results with the direct solution of the Schrödinger equation shows that the method can be confidently applied also in coupled-channel situations requiring high numerical accuracy.

To study heavy ion collisions at energies available from the Relativistic Heavy Ion Collider (RHIC), we have developed a multiphase transport model that includes both initial partonic and final hadronic interactions. Specifically, the Zhang’s parton cascade (ZPC) model, which uses as input the parton distribution from the heavy ion jet interaction generator (HIJING) model, is extended to include the quark-gluon–to–hadronic-matter transition and also final-state hadronic interactions based on a relativistic transport (ART) model. Predictions of the model for central Au on Au collisions at RHIC are reported.

The ${}^{14}\mathrm{N}{(n}_{\mathrm{th}}{,p)}^{14}\mathrm{C}$ reaction cross section was determined at the high flux reactor of the ILL in Grenoble using various polyimide and adenine samples. We obtained a precise value of $(1.93\mathrm{}\pm 0.05)\mathrm{b}$ for the cross section. A comparison is made with the currently available results in the literature and the astrophysical context is briefly discussed. Also the previously determined ${}^{17}\mathrm{O}{(n}_{\mathrm{th}},\alpha {)}^{14}\mathrm{C}$ cross section is renormalized taking into account this new result.

$U_A\mathrm{}\left(1\right)\mathrm{}$ symmetry breaking is studied by introducing the flavor mixing interaction proposed by Kobayashi, Maskawa, and ’t Hooft. Combining the one gluon exchange interaction, the rainbowlike Schwinger-Dyson equation and the ladderlike Bethe-Salpeter equation are derived. The anomalous PCAC relation in the framework of this approximation is considered. The masses of the pseudoscalar mesons $\pi ,$ $\eta ,$ and ${\eta }^{\prime }$ are calculated. It is found that the pion mass is not sensitive to the strength of the flavor mixing interaction. On the other hand, the masses of $\eta$ and ${\eta }^{\prime }$ are reproduced by a relatively weak flavor mixing interaction, for which the chiral symmetry breaking is dominantly induced by the soft-gluon exchange interaction. The decay constants are calculated and the anomalous PCAC relation is numerically checked. It is found that the flavor structures of the $\eta$ and ${\eta }^{\prime }$ mesons significantly depend on their masses and therefore it is questionable to define a flavor mixing angle for $\eta$ and ${\eta }^{\prime }.$

The $\gamma$-circular polarizations ${(P}_{\gamma })$ and asymmetries ${(A}_{\gamma })$ of several parity forbidden $\gamma$ transitions in ${}^{16}{\mathrm{O}}^{*}$ have been investigated within an effective operator approach. Considering various strong and weak interaction models, the maximum theoretical value among the circular polarizations has been found to be $1.85\times {10}^{-3}$ which corresponds to the 4.15 MeV $\gamma$ ray ${(2\mathrm{}}^{+}T=0;\hspace{0.5em}{E}_x=13.02\mathrm{}\hspace{0.5em}\mathrm{MeV}\to 2^{-}T=0;\hspace{0.5em}{E}_x=8.87\mathrm{}\hspace{0.5em}\mathrm{MeV})$ in ${}^{16}{\mathrm{O}}^{*}.$ The isovector component of the parity nonconserving matrix element dominates the mixing of the parity doublet ${(2\mathrm{}}^{-}T=1;\hspace{0.5em}{E}_x=12.9686\mathrm{}\hspace{0.5em}\mathrm{MeV}-2^{+}T=0;\hspace{0.5em}{E}_x=13.02\mathrm{}\hspace{0.5em}\mathrm{MeV})$ in ${}^{16}{\mathrm{O}}^{*}.$

We propose a microscopic approach for quark many-body systems based on molecular dynamics. Using color confinement and one-gluon exchange potentials together with meson exchange potentials between quarks, we construct nucleons and nuclear/quark matter. Dynamical transition between confinement and deconfinement phases are studied at high baryon density with this molecular dynamics simulation.

We show that the tail of the chiral two-pion exchange nucleon-nucleon potential is proportional to the pion-nucleon $\left(\pi N\right)$ scalar form factor and discuss how it can be translated into effective scalar meson interactions. We then construct a kernel for the process $N\overrightarrow{N}\pi NN,$ due to the exchange of two pions, which may be used in either three-body forces or pion production in $\mathrm{NN}$ scattering. Our final expression involves a partial cancellation among three terms, due to chiral symmetry, but the net result is still important. We also find that, at large internucleon distances, the kernel has the same spatial dependence as the central $\mathrm{NN}$ potential and we produce expressions relating these processes directly.

It is proposed that the odd-even staggering (OES) in the $\gamma$ bands of heavy deformed nuclei can be reasonably characterized by a discrete approximation of the fourth derivative of the odd-even energy difference as a function of angular momentum L. This quantity exhibits a well-developed staggering pattern (zigzagging behavior with alternating signs) in rare-earth nuclei and actinides with long $\gamma$ bands $(L>~10).$ It is shown that the OES can be interpreted as the result of the interaction of the $\gamma$ band with the ground band in the framework of a vector boson model with SU(3) dynamical symmetry. The model energy expression reproduces reasonably the staggering pattern in the considered nuclei up to $L=12\mathrm{}–13.$ The general behavior of the OES effect in rotational regions is studied in terms of the ground-$\gamma$ band-mixing interaction, showing that a strong OES effect occurs in regions with strong ground-$\gamma$ band-mixing interaction. The approach used allows a detailed comparison of the OES in $\gamma$ bands with the other kinds of staggering effects in nuclei and diatomic molecules.

The present work reports results for (i) $\mathrm{pd}$ radiative capture observables at center-of-mass (c.m.) energies $<~2$ MeV; (ii) contributions to the Gerasimov-Drell-Hearn (GDH) integral of ${}^3\mathrm{He}$ in the threshold region; and (iii) longitudinal, transverse, and interference response functions, at excitation energies below the threshold for breakup into $ppn,$ of interest in ${}^3\mathrm{He}\to \left(\overrightarrow{e}{,e}^{\prime }\right)$ experiments. An exhaustive comparison of these results with available data from the TUNL and Wisconsin groups for $\mathrm{pd}$ capture, and from the Saskatoon group for threshold electrodisintegration of ${}^3\mathrm{He},$ is carried out. The calculations are based on pair-correlated-hyperspherical-harmonics bound and continuum wave functions obtained from a realistic Hamiltonian consisting of the Argonne $v_{18}$ two-nucleon and Urbana IX three-nucleon interactions. The electromagnetic current operator includes one- and two-body components, leading terms of which are constructed from the Argonne $v_{18}$ interaction. The theoretical predictions obtained by including only one-body currents are in violent disagreement with data. These differences between theory and experiment are, to a large extent, removed when two-body currents are taken into account, although some rather large discrepancies remain in the c.m. energy range 0–100 keV, particularly for the $\mathrm{pd}$ differential cross section $\sigma \left(\theta \right)$ and tensor analyzing power $T_{20}\left(\theta \right)$ at small angles, and contributions to the GDH integral. A rather detailed analysis indicates that these discrepancies have, in large part, a common origin, and can be traced back to an excess of $E_1$ strength obtained in the theoretical calculation as compared to that observed experimentally. It is suggested that this fact might have implications for the nuclear interaction at very low energies. Finally, the validity of the long-wavelength approximation for electric dipole transitions is discussed.

We consider the deviations from electromagnetic high-energy scattering and photoproduction of leptons in the field of pointlike nuclei, generated by a nuclear charge distribution. The concept of the eikonal form factor for the description of scattering is briefly reviewed. In the region of small momentum transfers a coherence phenomenon of multiphoton exchange is discussed. The strong dependence of the non-Coulomb corrections to the photoproduction cross section of light lepton pairs upon the nuclear charge and the lepton mass can be traced back to this coherence effect. The higher-order corrections found for photoproduction are used to estimate the higher-order corrections to lepton pair production in ultrarelativistic heavy-ion collisions in logarithmic accuracy.

The centrality dependence of directed and elliptic flow in light and heavy systems of colliding nuclei is studied within two microscopic transport models at energies from $1A$ GeV to $160A$ GeV. The pion-directed flow has negative slope in the midrapidity range irrespective of bombarding energy and mass number of the colliding ions. In contrast, the directed flow of nucleons vanishes and even develops antiflow in the midrapidity range in (semi)peripheral collisions at energies around $11.6A$ GeV and higher. The origin of the disappearance of flow is linked to nuclear shadowing. Since the effect is stronger for a light system, it can be distinguished from a similar phenomenon caused by quark-gluon plasma formation. In the latter case the disappearance of flow due to the softening of the equation of state should be most pronounced in collisions of heavy ions. The centrality dependence of the elliptic flow shows that the maximum in the $〈v_2\mathrm{}\left(b\right)\mathrm{}〉$ distribution is shifted to very peripheral events with rising incident energy, in accordance with experimental data. This is an indication of the transition from baryonic to mesonic degrees of freedom in hot hadronic matter.

Within the framework of an isospin-dependent quantum molecular-dynamics model, the rotational flow in reactions of ${}^{58}\mathrm{Fe}{+}^{58}\mathrm{Fe}$ and ${}^{58}\mathrm{Ni}{+}^{58}\mathrm{Ni}$ at 40 MeV/nucleon for different impact parameters is investigated by analyzing the midrapidity azimuthal distribution. The rotational observables are also calculated semiquantitatively. For the first time, it is found that the more neutron-rich system ${(}^{58}\mathrm{Fe}{+}^{58}\mathrm{Fe})$ exhibits stronger rotational collective flow. This isospin dependence of rotational collective flow is more appreciable in semiperipheral collisions and it is shown to mainly result from the isospin dependence of nucleon-nucleon cross section rather than the symmetry energy. Meanwhile, it is indicated that the rotational flow depends strongly on the impact parameter.

Monochromatic x rays have been used to explore the phenomenon of nuclear excitation by electronic transition (NEET) in the ${}^{189}\mathrm{Os}$ atomic/nuclear system. A new theoretical approach to calculating this process has also been developed and predicts a value for the “NEET probability,” $P_{\mathit{NEET}},$ of $1.3\times {10}^{-10}.$ $P_{\mathit{NEET}}$ is the probability that a given atomic excitation (in this case a K vacancy), will result in the excitation of a specific nuclear state (in this case the 69.5-keV level in ${}^{189}\mathrm{Os}).\mathrm{}$ This value is much lower than most of the calculated values given in the literature for this system. Our measurement gives the result $P_{\mathit{NEET}}<9\mathrm{}\times {10}^{-10},$ an upper limit which is several orders of magnitude lower than the values found in previous measurements, but which is consistent with the new calculation.

We have measured the lifetimes of the weak decay of ${}_{\Lambda }^{12}\mathrm{C},$ ${}_{\Lambda }^{28}\mathrm{Si},$ and ${}_{\Lambda }^{56}\mathrm{Fe}$ hypernuclei which were produced via a $\left({\pi }^{+}{,K}^{+}\right)$ reaction at KEK 12-GeV PS. The lifetimes were obtained by direct measurement of the production and decay time of the hypernucleus using a fast timing counter system whose time resolution was about 83 ps. Our results for the lifetimes of ${}_{\Lambda }^{12}\mathrm{C},$ ${}_{\Lambda }^{28}\mathrm{Si},$ and ${}_{\Lambda }\mathrm{Fe}$ are $231\pm 15,$ $206\pm 11,$ and $215\pm 14\hspace{0.5em}\mathrm{ps},$ respectively. The lifetimes of ${}_{\Lambda }^{11}\mathrm{B}$ and ${}_{\Lambda }^{27}\mathrm{Al}$ with the application of the gate to the $p_{\Lambda }$ state of the formation spectra of ${}_{\Lambda }^{12}\mathrm{C}$ and ${}_{\Lambda }^{28}\mathrm{Si}$ were also determined to be $211\pm 13$ and $203\pm 10\hspace{0.5em}\mathrm{ps}.$ From the present work, it was found that the total decay width saturates according to the hypernuclear mass number even at $A\sim 12.$ This suggests the importance of the proper treatment of the short range nature of the nonmesonic decay of $\Lambda$ hypernuclei.

The low-lying $M1\mathrm{}$ transition strength distributions observed in rare earth and actinide nuclei reflects on both the collective and noncollective aspects of the nuclear interaction. As shown in this article, the pseudo-SU(3) model can accommodate these complementary features and provides a natural interpretation for different aspects of this “scissors” mode.

The neutron-rich nuclei, ${}^{66}\mathrm{Co},$ ${}^{68}\mathrm{Co},$ and ${}^{70}\mathrm{Co}$ were produced using a laser-ionization isotope-separation on-line method. The resulting $\beta$-delayed $\gamma$ decay was studied. The half-life of ${}^{66}\mathrm{Co}$ is measured to be 0.18(1) s. Two $\beta$-decaying states are identified in ${}^{68}\mathrm{Co}$ with half-lives of 0.23(3) and 1.6(3) s. In addition, two $\beta$-decaying states are observed in ${}^{70}\mathrm{Co}$ with half-lives of 0.12(3) and 0.50(18) s. From the $\beta$ decay of these states in ${}^{66,68,70}\mathrm{Co},$ many new excited levels are established in ${}^{66}\mathrm{Ni},$ ${}^{68}\mathrm{Ni},$ and ${}^{70}\mathrm{Ni}.$ These results are compared to the valence mirror nuclei in the $N=50\mathrm{}$ region as well as with shell-model calculations. It can be concluded that collective excitations appear to play an increasingly important role with increasing occupation of the $\nu g_{9/2}$ orbital.

We continue the investigations of the ${}^{16}\mathrm{O}$ ground state using the coupled-cluster expansion $\left[\exp \right(\mathbf{S}\left)\right]$ method with realistic nuclear interaction. In this stage of the project, we take into account the three nucleon interaction, and examine in some detail the definition of the internal Hamiltonian, thus trying to correct for the center-of-mass motion. We show that this may result in a better separation of the internal and center-of-mass degrees of freedom in the many-body nuclear wave function. The resulting ground state wave function is used to calculate the “theoretical” charge form factor and charge density. Using the “theoretical” charge density, we generate the charge form factor in the DWBA picture, which is then compared with the available experimental data. The longitudinal response function in inclusive electron scattering for ${}^{16}\mathrm{O}$ is also computed.

Measurements of prompt $\gamma$ rays, following neutron capture in ${}^{107}\mathrm{Ag}$ and ${}^{109}\mathrm{Ag}$ have been performed at the GELINA facility in the resonance energy region up to about 1 keV. From the intensities of low- and high-energy $\gamma$ rays the spins of 53 ${}^{107}\mathrm{Ag}$ and 78 ${}^{109}\mathrm{Ag}$ s- and p-wave resonances have been assigned. These spectroscopic quantities are important for the interpretation of data from parity violation experiments performed by the TRIPLE Collaboration. The intensities of low-energy transitions showed a dependence not only on the spin of the resonance but also on its parity. This effect allows the assignment of the parity of the resonances and may open new perspectives in the study of the $\gamma$ decay of the compound nucleus.

The general formalism of nucleon recoil polarization in the $\left(\overrightarrow{e}{,e}^{\prime }\overrightarrow{N}N\right)$ reaction is given. Numerical predictions are presented for the components of the outgoing proton polarization and of the polarization transfer coefficient in the specific case of the exclusive ${}^{16}\mathrm{O}(\overrightarrow{e}{,e}^{\prime }\overrightarrow{p}{p)}^{14}\mathrm{C}$ knockout reaction leading to discrete states in the residual nucleus. Reaction calculations are performed in a direct knockout framework where final-state interactions and one-body and two-body currents are included. The two-nucleon overlap integrals are obtained from a calculation of the two-proton spectral function of ${}^{16}\mathrm{O}$ where long-range and short-range correlations are consistently included. The comparison of results obtained in different kinematics confirms that resolution of different final states in the ${}^{16}\mathrm{O}(\overrightarrow{e}{,e}^{\prime }\overrightarrow{p}{p)}^{14}\mathrm{C}$ reaction may act as a filter to disentangle and separately investigate the reaction processes due to short-range correlations and two-body currents and indicates that measurements of the components of the outgoing proton polarization may offer good opportunities to study short-range correlations.