The ground-state configuration of the $N=157$ nucleus ${}^{259}$No has been identified through $\alpha$-$\gamma$ coincidence and $\alpha$-singles measurements. Three $\gamma$ transitions were observed for the first time in the $\alpha$ decay of ${}^{259}$No, and its decay scheme was established. The neutron 9/2${}^{+}$[615] configuration was assigned to the ground state of ${}^{259}$No as well as to the 231.4 keV level in ${}^{255}$Fm. Ground-state deformations and neutron single-particle energies in $Z=102$ isotopes were calculated with the macroscopic-microscopic model. The 9/2${}^{+}$[615] orbital was calculated to be the highest among the five orbitals between the $N=152$ and 162 deformed shell gaps, which is consistent with the experimental one-quasiparticle energies in $N=153$ and 155 isotones, but is inconsistent with the present experimental result of the 9/2${}^{+}$[615] ground state at $N=157$. To reproduce the 9/2${}^{+}$[615] ground state at $N=157$, the order of the neutron orbitals should be different between the $N=153$ and 157 isotones.

The valence neutron composition of the ${}^{130}$Te and ${}^{130}$Xe ground states has been studied with a view to constraining calculations of the nuclear matrix element for the neutrinoless double-$\beta$ decay of ${}^{130}$Te. Single-neutron adding and removing reactions on ${}^{128,130}$Te and ${}^{130,132}$Xe have been used to probe the vacancy of the $0g_{7/2}$, $1d_{5/2}$, $1d_{3/2}$, $2s_{1/2}$, and $0h_{11/2}$ orbitals. The change in the vacancy of these orbitals, obtained through a self-consistent determination of spectroscopic factors utilizing the Macfarlane-French sum rules, for ${}^{130}\mathrm{Te}\to {}^{130}\mathrm{Xe}$ is shared only between the $d$, $s_{1/2}$, and $h_{11/2}$ orbitals, with the $g_{7/2}$ playing no significant role. This is in disagreement with recent calculations within both the quasiparticle random-phase approximation and shell-model frameworks, which show a role for the $g_{7/2}$ orbital that should have been observable. The neutron pairing properties of ${}^{130}$Xe have also been explored through the ${}^{132}$Xe($p$,$t$) reaction showing no evidence for pairing vibrations.

The cross section of the reaction ${}^{136}$Xe(n,2n)${}^{135}$Xe to both the ground state and the 526.6 keV isomeric states of ${}^{135}$Xe was measured between 9.0 and 14.9 MeV. These data are important to guide evaluations and theoretical calculations aimed at estimating the importance of neutron-induced background effects in searches for neutrinoless double-β decay of ${}^{136}$Xe.

Background: The nuclei in the region around ${}^{68}$Ni display an apparent rapid development of collectivity as protons are removed from the $f_{7/2}$ single-particle state along the $N=40$ isotonic chain. Proton and neutron excitations across the $Z=28$ and $N=40$ gaps are observed in odd-A ${}_{27}$Co and ${}_{26}$Fe isotopes. Little spectroscopic information beyond the excited 2${}^{+}$ and 4${}^{+}$ is available in the even-even  ${}_{26}^{66,68}\mathrm{Fe}$ nuclei to compare with shell model calculations.

Purpose: Our goal is to determine the low-energy level schemes of ${}^{66,68}$Fe and compare the observed excitations with shell model calculations to identify states wherein a contribution from excitations across $Z=28$ and $N=40$ are present.

Method: The low-energy states of ${}^{66,68}$Fe were populated through the beta decay of ${}^{66,68}$Mn produced at the National Superconducting Cyclotron Laboratory. Beta-delayed gamma-ray transitions were detected and correlated to the respective parent isotope to construct a low-energy level scheme.

Results: The low-energy level schemes of ${}^{66,68}$Fe were constructed from observed gamma-ray coincidences and absolute gamma-ray intensities. Tentative spin and parity assignments were assigned based on comparisons with shell model calculations and systematics. The two lowest 0${}^{+}$ and 2${}^{+}$ states were characterized in terms of the number of protons and neutrons excited across the respective shell gaps.

Conclusion: The removal of two protons from ${}^{68}$Ni to ${}^{66}$Fe results in an inversion of the normal configuration and the one characterized by significant excitation across the $Z=28$ and $N=40$ gaps. Approximately, one proton and two neutrons are excited across their respective single-particle gaps in the ground state of ${}^{66}$Fe.

Deep-inelastic reactions and $\gamma$-ray spectroscopy have been used to study excited states in ${}^{195}$Au. A three-quasiparticle isomer with a mean-life of 18.6(3) $\mu$s has been assigned at 2461+$\Delta$ keV, with decays into newly identified structures. Possible configurations for the isomer are discussed including a $J^{\pi }$  $=$31/2${}^{-}$ intrinsic state produced by coupling the 11/2${}^{-}$[505] proton hole to the 10${}^{+}$ state obtained from the 9/2${}^{+}$[624],11/2${}^{+}$[615] two-neutron holes, expected from configuration-constrained potential-energy-surface calculations. Residual interactions are evaluated within a semi-empirical shell model basis. New lifetime information is also obtained for the 21/2${}^{+}$ and 25/2${}^{+}$ states at 1813 and 1980 keV. The relationship between these and other newly identified states and the negative-parity states in the even-even neighbors is discussed.

We solve the ab initio no-core shell model (NCSM) in the complete $8\hslash \Omega$ ($N_{\max }=8$) basis for $A=7$ and $A=8$ nuclei with two-nucleon and three-nucleon interactions derived within chiral effective field theory (EFT). We find that including the chiral EFT three-nucleon interaction in the Hamiltonian improves overall agreement with experimental binding energies, excitation spectra, transitions, and electromagnetic moments. We predict states that exhibit sensitivity to including the chiral EFT three-nucleon interaction but are not yet known experimentally.

Within the framework of the Brueckner theory, the off-shell behaviors of the mass operator $M(k,\omega )=V(k,\omega )+iW(k,\omega )$, i.e., its dependence upon the momentum $k$ and upon the nucleon frequency $\omega$, are investigated by including nuclear three-body force (TBF). The first two terms of the hole-line expansion of the mass operator are taken into account. The TBF effects on their off-shell properties are discussed. A comparison is made between the on-shell and off-shell values of $M_1$. The nucleon spectral function and nucleon momentum distribution are also calculated, and the calculation shows that they are hardly affected by the TBF effect at the saturation density. At a density two times greater than the saturation density, inclusion of the TBF may lead to a visible effect on the spectral function and may enhance the depletion of the hole states.

Excited states in ${}^{129}$I were populated with the ${}^{124}$Sn(${}^7$Li,$2n$) reaction at 23 MeV. In-beam measurements of $\gamma$-ray coincidences were performed with an array of eight HPGe detectors and five LaBr${}_3$(Ce) scintillation detectors. Based on the $\gamma \gamma$ coincidence data, a positive parity band structure built on the $7/2^{+}$ ground state was established and the $\pi g_{7/2}$ configuration at oblate deformation was assigned to it. The results are compared to interacting Boson-Fermion model (IBFM) and total Routhian surface (TRS) calculations.

This paper deals with the solution of the spherically symmetric time-dependent Hartree-Fock approximation applied in the case of nuclear giant monopole resonances in the small and large amplitude regimes. The problem is spatially unbounded as the resonance state is in the continuum. The practical requirement to perform the calculation in a finite-sized spatial region results in a difficulty with the spatial boundary conditions. Here we propose an absorbing boundary condition scheme to handle the conflict. The derivation, via a Laplace transform method, and implementation is described. The accuracy and efficiency of the scheme is tested and the results presented to support the case that they are a effective way of handling the artificial boundary.

We present an efficient numerical technique to evaluate the matrix of the (quasiparticle-) random-phase approximation, using the finite-amplitude method (FAM). The method is tested in calculation of monopole excitations in ${}^{120}$Sn, compared with result obtained with the former iterative FAM. The neutron-pair-transfer modes are calculated with the present method and their character change in neutron-rich Pb isotopes is discussed. Computational aspects of different FAM approaches are also discussed for future applications to a large-scale computation.

The fusion excitation function of ${}^{32}$S + ${}^{48}$Ca has been experimentally studied in a wide energy range, from above the Coulomb barrier down to cross sections in the sub-$\mu$b region. The measurements were done at INFN–Laboratori Nazionali di Legnaro, using the ${}^{32}$S beam from the XTU Tandem accelerator. The excitation function has a smooth behavior below the barrier, and no evident hindrance character shows up in the measured energy region. The fusion barrier distribution has a peculiar shape with two distinct peaks of similar height, lower and higher than the Akyüz-Winther barrier. Coupled-channels calculations using the M3Y + repulsion potential are presented for this system and for ${}^{36}$S + ${}^{48}$Ca. The results of these calculations give a good account of the data, and indicate the influence of one- and two-nucleon transfer channels with positive $Q$ values, which are only open for ${}^{32}$S + ${}^{48}$Ca.

The cross sections of the ${}^{238}$U($n$,3$n$)${}^{236}$U reaction induced by neutrons with energies around 14 MeV were determined using a combination of the activation technique and accelerator mass spectrometry (AMS) at the China Institute of Atomic Energy (CIAE). U${}_3$O${}_8$ samples were irradiated for 198 h by neutrons produced by the ${}^3$H($d$,$n$)${}^4$He reaction on a 600-kV neutron generator at CIAE. Neutron flux was continuously determined by the activation of flux monitors, Co foils, closely attached to the sample. To accurately determine the long half-life product ${}^{236}$U, an AMS procedure was established with a sensitivity of about 10${}^{-11}$ for ${}^{236}$U/${}^{238}$U. As a result, the cross sections of ${}^{238}$U($n$,3$n$)${}^{236}$U for the incident neutron energies of ($14.18\pm 0.30$) and ($14.65\pm 0.40$) MeV were obtained to be ($489.3\pm 48.0$) and ($556.7\pm 27.8$) mb, respectively.

Evaporation protons from the fusion of the ${}^3\mathrm{He}{+}^{58}$Ni system were measured at three energies near but above the Coulomb barrier. The respective elastic scattering angular distribution was also determined for one of these energies. The fusion data, after being properly reduced to eliminate size and charge effects, are compared to the recently measured fusion excitation function for the proton-halo system ${}^8\mathrm{B}{+}^{58}$Ni. As a reference, fusion data for the ${}^{16}\mathrm{O}{+}^{58}$Ni system are also presented. With respect to this reference, the fusion cross sections for the proton-rich systems show an enhancement likely related to static effects. An excitation function for the respective total-reaction cross section was extracted from the measured elastic data along with additional data from the literature. Surprisingly, this excitation function follows the trend expected for weakly bound systems.

We attempt to make some progress in the problem of the apparently large diffuseness of the Woods-Saxon strong nucleus-nucleus interaction potential (SnnP) needed to fit a large number of precision fusion excitation functions. This problem has been formulated in Newton et al. [Phys. Lett. B 586, 219 (2004);Phys. Rev. C 70, 024605 (2004)]. We applied the classical dissipative trajectory model to describe the data on fusion (capture) of ${}^{16}\mathrm{O}$ with ${}^{92}\mathrm{Zr},$ ${}^{144}\mathrm{Sm},$ and ${}^{208}\mathrm{Pb}.$ No fluctuations or dynamical deformations of the interacting nuclei are accounted for. The friction force is supposed to be proportional to the squared derivative of the SnnP (the surface friction model). The SnnP is calculated within the framework of the double-folding model with the density-dependent M3Y $NN$ forces. This potential is known to possess rather small diffuseness in contradistinction to what is required by the data analysis in Newton et al. [Phys. Lett. B 586, 219 (2004);Phys. Rev. C 70, 024605 (2004)]. Varying slightly the strength of radial friction (universally for all three reactions) and the diffuseness of the charge density of ${}^{208}\mathrm{Pb}$ we have obtained satisfactory agreement of the calculated excitation functions with the data.

We have performed continuum discretized coupled channel (CDCC) calculations for the ${}^6$Li + ${}^{59}$Co, ${}^{144}$Sm, and ${}^{208}$Pb systems, to investigate the dependence of the relative importance of nuclear and Coulomb breakup on the target charge (mass) at near-barrier energies. The calculations were in good agreement with the experimental elastic scattering angular distributions for these systems and then their predictions to the nuclear, Coulomb, and total breakup were investigated. Although the relative importance of the nuclear breakup is, as expected, larger for lighter targets, this effect is not very pronounced. We also investigate a scaling of the nuclear breakup with the target mass and we compare the predictions for the integrated total breakup cross sections with experimental fusion cross sections at similar energies.

We explore the available parameter space that gives reasonable fits to the total charm cross section to make a better estimate of its true uncertainty. We study the effect of the parameter choices on the energy dependence of the $J/\psi$ cross section.

The nucleon's axial charge, $g_A$, expresses features that are both fundamental to the strong interaction and crucial to its connection with weak-interaction physics. We show that dynamical chiral symmetry breaking (DCSB) suppresses the axial charge of a dressed quark, $g_A^q$, at infrared momenta. Since this effect disappears as chiral symmetry is restored, one may argue that $g_A$ vanishes with the restoration of chiral symmetry because no nucleon bound state survives the associated transition. The suppression of $g_A^q$ is shown to be part of an explanation for a 25$\%$ reduction of $g_A$ from its nonrelativistic quark-model value. Critical, too, however, is the presence of dressed-quark angular momentum within the nucleon. The value of $g_A^q$ depends on the kernels of the gap and Bethe-Salpeter equations. We find that incorporation of essentially nonperturbative effects associated with DCSB into these kernels inflates the value relative to that obtained at leading order in a widely used truncation of QCD's Dyson-Schwinger equations. Such corrections also affect the nucleon's axial radius. In both cases, however, agreement with experiment will require similar improvements to the Faddeev kernel and associated interaction current.

We calculate the nucleon self-energies in isospin-asymmetric nuclear matter using QCD sum rules. Taking the difference of these for the neutron and proton enables us to express the potential part of the nuclear symmetry energy in terms of local operators. We find that the scalar (vector) self-energy part gives a negative (positive) contribution to the nuclear symmetry energy which is consistent with the results from relativistic mean-field theories. Moreover, we find that an important contribution to the negative contribution of the scalar self-energy comes from the twist-4 matrix elements, whose leading density dependence can be extracted from deep inelastic scattering experiments. This suggests that the twist-4 contribution partly mimics the exchange of the $\delta$ meson and that it constitutes an essential part in the origin of the nuclear symmetry energy from QCD. Our result also extends an early success of QCD sum-rule method in understanding the symmetric nuclear matter in terms of QCD variables to the asymmetric nuclear matter case.

We apply an extended version of the SU(3) parity model, containing quark degrees of freedom, to study neutron stars. The model successfully reproduces the main thermodynamic features of QCD which allows us to describe the composition of dense matter. Chiral symmetry restoration is realized inside the star and the chiral partners of the baryons appear, their masses becoming degenerate. Furthermore, quark degrees of freedom appear in a transition to a deconfined state. Performing an investigation of the macroscopic properties of neutron stars, we show that observational constraints, such as mass and thermal evolution, are satisfied and new predictions can be made.

Background: Recent experiments on the electric dipole (E1) polarizability in heavy nuclei have stimulated theoretical interest in the low-energy electric dipole strength, both isovector and isoscalar.

Purpose: We study the information content carried by the electric dipole strength with respect to isovector and isoscalar indicators characterizing bulk nuclear matter and finite nuclei. To separate isoscalar and isovector modes, and low-energy strength and giant resonances, we analyze the E1 strength as a function of the excitation energy $E$ and momentum transfer $q$.

Methods: We use the self-consistent nuclear density functional theory with Skyrme energy density functionals, augmented by the random phase approximation, to compute the E1 strength and covariance analysis to assess correlations between observables. Calculations are performed for the spherical, doubly magic nuclei ${}^{208}$Pb and ${}^{132}$Sn.

Results: We demonstrate that E1 transition densities in the low-energy region below the giant dipole resonance exhibit appreciable state dependence and multinodal structures, which are fingerprints of weak collectivity. The correlation between the accumulated low-energy strength and the symmetry energy is weak, and dramatically depends on the energy cutoff assumed. On the other hand, a strong correlation is predicted between isovector indicators and the accumulated isovector strength at $E$ around 20 MeV and momentum transfer $q\sim 0.65$ fm${}^{-1}$.

Conclusions: Momentum- and coordinate-space patterns of the low-energy dipole modes indicate a strong fragmentation into individual particle-hole excitations. The global measure of low-energy dipole strength correlates poorly with the nuclear symmetry energy and other isovector characteristics. Consequently, our results do not support the suggestion that there exists a collective “pygmy dipole resonance,” which is a strong indicator of nuclear isovector properties. By considering nonzero values of momentum transfer, one can isolate individual excitations and nicely separate low-energy excitations from the $T=1$ and $T=0$ giant collective modes. That is, measurements at $q>0$ may serve as a tool to correlate the E1 strength with certain bulk observables, such as incompressibility and symmetry energy.