In the scattering of positive pions by nuclei the double-charge-exchange (DCX) reaction creates the possibility of the formation of pionic atom states in the vicinity of the threshold of the reaction. These quasistationary states can manifest themselves as resonances in the elastic scattering cross section. The strength and shape of these resonances are strongly affected by the instability of the nucleus created in the DCX channel. It is shown that this mechanism can explain oscillation structures in the excitation function observed in scattering of low-energy positive pions from ${}^{12}\mathrm{C}$.

Intensity distributions of cascade $\gamma$-ray transitions following the capture of thermal neutrons by ${}^{113}$Cd have been measured at the Los Alamos Neutron Science Center for various $\gamma$-ray multiplicities. The experiment was carried out at the highly segmented $4\pi$ $\gamma$-ray calorimeter—Detector for Advanced Neutron Capture Experiments (DANCE). A measured two-dimensional spectrum of counts versus $\gamma$-ray energy versus $\gamma$-ray multiplicity, from the strongest resonance in the ${}^{113}$Cd$(n,\gamma )$ reaction at 0.178 eV has been compared to predictions from the statistical model. The best representation of the $\gamma$-ray cascades following the capture of thermal neutrons on ${}^{113}$Cd is presented. The intensity distribution of these cascades is of great importance for estimates of response to thermal neutrons of devices that use natural or enriched cadmium.

Proton double-differential cross sections from ${}^{59}\mathrm{Co}(\alpha ,p){}^{62}\mathrm{Ni}$, ${}^{57}\mathrm{Fe}(\alpha ,p){}^{60}\mathrm{Co}$, ${}^{56}\mathrm{Fe}({}^7\mathrm{Li},p){}^{62}\mathrm{Ni}$, and ${}^{55}\mathrm{Mn}({}^6\mathrm{Li},p){}^{60}\mathrm{Co}$ reactions have been measured with 21-MeV $\alpha$ and 15-MeV lithium beams. Cross sections have been compared against calculations with the empire reaction code. Different input level density models have been tested. It was found that the Gilbert and Cameron [A. Gilbert and A. G. W. Cameron, Can. J. Phys. 43, 1446 (1965)] level density model is best to reproduce experimental data. Level densities and spin cutoff parameters for ${}^{62}\mathrm{Ni}$ and ${}^{60}\mathrm{Co}$ above the excitation energy range of discrete levels (in continuum) have been obtained with a Monte Carlo technique. Excitation energy dependencies were found to be inconsistent with the Fermi-gas model.

We study the hadronic effects on the $X\left(3872\right)$ meson abundance in heavy ion collisions. We evaluate the absorption cross sections of the $X\left(3872\right)$ meson by pions and rho mesons in the hadronic stage of heavy ion collisions, and further investigate the variation in the $X\left(3872\right)$ meson abundance during the expansion of the hadronic matter for its two possible quantum number states; $J^P=1^{+}$ and $2^{-}$. We show that the absorption cross sections and the time evolution of the $X\left(3872\right)$ meson abundance are strongly dependent on the structure and quantum number of the $X\left(3872\right)$ meson. We thus suggest that studying the abundance of the $X\left(3872\right)$ meson in relativistic heavy ion collisions provides a chance to infer its quantum number as well as its structure.

In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, effects of the symmetry energy on the evolutions of the free $n/p$ ratio and the charged pion ratio in the semicentral collision of ${}^{197}$Au+${}^{197}$Au at an incident beam energy of 400 MeV/nucleon are studied. At the beginning of the reaction (before 11 fm/$c$) they are both affected by the low-density behavior of the symmetry energy but soon after are affected by the high-density behavior of the symmetry energy after nuclei are compressed (after 11 fm/$c$), and the effects of the symmetry energy are generally smaller compared with the central collision case. Interestingly, their dependences on the symmetry energy are shown to rise with an increase of the cone-azimuthal angle of the emitted particles. In the direction perpendicular to the reaction plane, the ${\pi }^{-}/{\pi }^{+}$ ratio or the free $n/p$ ratio, especially at high kinetic energies, exhibits significant sensitivity to the symmetry energy.

The energy levels of the odd-odd nucleus ${}^{126}$I have been investigated by in-beam $\gamma$-ray spectroscopic techniques. Twenty seven new $\gamma$ transitions have been identified. The polarization analysis was carried out using the clover detector as a Compton polarimeter. We have made definite parity assignments to six bands. Five of them were in agreement with the previous assignments of parity, but one band for which the theoretical interpretation was earlier reported with an assumed negative parity [Zheng et al., Phys. Rev. C 86, 014320 (2012)] was found to be of positive parity. We have carried out the theoretical analysis of different bands using the particle rotor model and the calculations of the total Routhian surface. The signature inversion observed in the yrast negative-parity band has been understood as the change in the axis of rotation from the shortest to the intermediate axis of the triaxial nucleus. Two positive-parity bands based on the particle configuration $\pi h_{11/2}\otimes \nu h_{11/2}$, have been found to be good candidates for the chiral partner behavior.

To understand the low-energy structure of the neutron deficient iodine isotopes, lifetimes for the low-lying $9/2^{+}$ and $11/2^{+}$ positive-parity states in ${}^{113}$I have been measured as $\tau =28\left(4\right)$ ps and $\tau =3.7\left(7\right)$ ps, respectively. The lifetime for the $11/2^{-}$ state, which feeds the $9/2^{+}$ and $11/2^{+}$ states, was remeasured with improved accuracy as $\tau =216\left(7\right)$ ps. The reduced transition probability, $B\left(E2\right)=32\left(5\right)$ W.u., for the $9/2^{+}\to 5/2^{+}$ transition agrees with that calculated within the shell model using a Hamiltonian based on the charge-dependent Bonn nucleon-nucleon interaction. In contrast, the much larger transition probability, $B\left(E2\right)=209\left(39\right)$ W.u., measured for the $11/2^{+}\to 7/2^{+}$ transition has been interpreted, with the aid of configuration-constrained total Routhian surface calculations, as resulting from a slightly $\gamma$-soft rotor with an associated quadrupole deformation of ${\beta }_2\approx 0.18$. Remarkably similar reduced $E1$ transition probabilities of $5.5\left(5\right)\times {10}^{-4}$ and $4.9\left(5\right)\times {10}^{-4}$ W.u. were deduced for the $11/2^{-}\to 9/2^{+}$ and $11/2^{-}\to 11/2^{+}$ transitions, respectively, which feed apparently dissimilar but competing structures.

Within a dynamical and statistical approach we study the main regularities in the production of hypernuclei coming from projectile and target residues in relativistic ion collisions. We demonstrate that yields of hypernuclei increase considerably above the energy threshold for $\Lambda$ hyperons and there is a saturation for yields of single hypernuclei with increasing the beam energy up to few TeV. The production of specific hypernuclei depend very much on the isotopic composition of the projectile, and this gives a chance to obtain exotic hypernuclei that may be difficult to reach in traditional hypernuclear experiments. Possibilities for the detection of such hypernuclei with planned and available relativistic ion facilities are discussed.

Using the stochastic Langevin model, we calculate the evolution of postsaddle giant dipole resonance (GDR) $\gamma$-ray multiplicity ($M_{\gamma }$) as a function of the postsaddle friction strength ($\beta$) with excitation energy for ${}^{240}$Cf, ${}^{224}$Th, and ${}^{200}$Pb systems. It is found that with raising the excitation energy the sensitivity of the postsaddle $\gamma$ emission to friction is substantially increased. We further find that $M_{\gamma }$ shows a greater sensitivity to $\beta$ with increasing size of the fissioning nucleus. The results suggest that on the experimental side, populating those fissioning systems with a large size and a high energy favors better determination of the postsaddle friction strength by measuring the GDR $\gamma$ multiplicity emitted in the fission process.

We analyze the mixing nature of the low-lying scalar resonance consisting of the $\pi \pi$ composite and the elementary particle within the $\sigma$ model. A method to disentangle the mixing is formulated in the scattering theory with the concept of the two-level problem. We investigate the composite and elementary components of the $\sigma$ meson by changing a mixing parameter. We also study the dependence of the results on model parameters such as the cut-off value and the mass of the elementary $\sigma$ meson.

Recent results from a measurement campaign studying the isomerism in neutron-deficient Tl isotopes are presented. The measurements make use of a nuclear spectroscopy setup coupled to the high-resolution Penning-trap mass spectrometer ISOLTRAP at CERN's radioactive ion-beam facility ISOLDE. The mass values of ${}^{190,194}$Tl are improved and a mass-spin-state assignment is carried out. An additional mass measurement of the grandparent nuclide ${}^{198}$At allows the deduction of the spin-state ordering in ${}^{190}$Tl. As a result, the excitation energies of the isomers in both Tl isotopes are determined for the first time to $E_{\mathrm{ex}}{(}^{194}\text{Tl})=260\left(15\right)$ keV and $E_{\mathrm{ex}}{(}^{190}\text{Tl})=89\left(12\right)$ keV. Furthermore, this allows anchoring of the ground-state and isomer masses of ${}^{194}$Bi, ${}^{202}$Fr, and ${}^{206}$Ac, which are linked by two independent $\alpha$-decay chains.

Weakly bound deformed nuclei have been studied by the Skyrme Hartree-Fock-Bogoliubov (HFB) approach in large coordinate-space boxes. In particular, the box-size dependence of the HFB calculations of weakly bound deformed nuclei are investigated, including the particle density and pairing density distributions at nuclear surfaces, the near-threshold resonant and continuum quasiparticle spectra, and energetic properties. The box size may have larger influences in pairing properties than in other bulk properties. We demonstrate that large-box calculations of weakly bound nuclei are important to precisely describe exotic phenomena such as deformed halos and peninsulas of stability beyond drip lines.

A realistic density-dependent nucleon-nucleon ($NN$) interaction with a finite-range exchange part which produces the nuclear matter saturation curve and the energy dependence of the nucleon-nucleus optical model potential is used to calculate the microscopic $\alpha$-nucleus potential in the well-established double-folding model. The main effect of antisymmetrization under exchange of nucleons between the $\alpha$ and daughter nuclei has been included in the folding model through the finite-range exchange part of the $NN$ interaction. The $\alpha$-decay half-lives have been determined using a microscopic potential within the semiclassical Wentzel-Kramers-Brillouin approximation in combination with the Bohr-Sommerfeld quantization condition. We systematically studied the preformation probability, $S_{\alpha }$, for ten even-even and odd mass heavy nuclei from Po to No isotopes. We found that $S_{\alpha }$ has a regular behavior with $N$ if the $\alpha$ particle emitted from adjacent isotopes comes from the same energy levels or from a group of levels, assuming that the order of levels in this group is not changed. Sudden increase in $S_{\alpha }$ is found when protons and neutrons holes exist below the Fermi levels. Based on the similarity in the behavior of $S_{\alpha }$ with the neutron number for two adjacent nuclei, we try to determine the unknown or doubted nuclear spins and parities or at least correlate spins of adjacent nuclei.

We report on the experimental study of quadrupole collectivity in the neutron-deficient nucleus ${}^{104}$Sn using intermediate-energy Coulomb excitation. The $B(E2;0_1^{+}\to 2_1^{+})$ value for the excitation of the first $2^{+}$ state in ${}^{104}$Sn has been measured to be $0.180\left(37\right)e^2$b${}^2$ relative to the well-known $B\left(E2\right)$ value of ${}^{102}$Cd. This result disagrees by more than one sigma with a recently published measurement [G. Guastalla et al.,  Phys. Rev. Lett. 110, 172501 (2013)]. Our result indicates that the most modern many-body calculations remain unable to describe the enhanced collectivity below midshell in Sn approaching $N=Z=50$. We attribute the enhanced collectivity to proton particle-hole configurations beyond the necessarily limited shell-model spaces and suggest the asymmetry of the $B\left(E2\right)$-value trend around midshell to originate from enhanced proton excitations across $Z=50$ as $N=Z$ is approached.

We present a detailed analysis of nuclear effects in inclusive electron scattering from polarized ${}^3$He nuclei for polarization asymmetries, structure functions, and their moments, in both the nucleon-resonance and deep-inelastic regions. We compare the results of calculations within the weak binding approximation at finite $Q^2$ with the effective polarization ansatz often used in experimental data analyses and explore the impact of $\Delta$ components in the nuclear wave function and nucleon off-shell corrections on extractions of the free neutron structure. Using the same framework we also make predictions for the $Q^2$ dependence of quasielastic scattering from polarized ${}^3$He, data which can be used to constrain the spin-dependent nuclear smearing functions in ${}^3$He.

The extended random-phase approximation (RPA) theories are analyzed from the point of view of the problem of the stability of their solutions. Three kinds of such theories are considered: the second RPA and two versions of the quasiparticle-phonon coupling model within the time-blocking approximation: the model including $1p1h\otimes$phonon configurations and the two-phonon model. It is shown that stability is ensured by making use of the subtraction method proposed previously to solve the double counting problem in these theories. This enables one to generalize the famous Thouless theorem proved in the case of the RPA. These results are illustrated by an example of the schematic model.

Proton emission from deformed nuclei near the drip line is regarded as a versatile tool in nuclear structure physics and such a study in odd-odd nuclei provides us with an excellent opportunity to understand several interesting features including the interaction between the valence proton and the valence neutron. We present a detailed formalism for a full microscopic calculation of such proton emitters, where the nuclear structure and decay aspects are taken into account exactly. This formalism is based on the nonadiabatic approach for the two quasiparticle plus rotor model, where the residual neutron-proton interactions are considered in the mean field represented by a deformed Woods-Saxon potential. We demonstrate a systematic way of unambiguously identifying several parameters involved in the calculations with the aid of the experimental data. The quality of results in the case of ${}^{180}$Ta justifies the approach which is further extended to discuss in detail the proton emission from ${}^{130}$Eu. $I^{\pi }=1^{+}$ state in ${}^{130}$Eu still remains to be the proton emitting state irrespective of the choice of several parameters. We also note that the decay widths could be quite sensitive to the residual $np$ interaction in case of proton emission from isomeric states.

In this paper we study the spin-$J$ nucleon-pair approximation for a single-$j$ shell, with a simple $J$-pairing interaction. For a four-nucleon system, the $J$-pair truncation works remarkably well, in particular for isospin $T=0$ states. The lowest $I=0$ states of four nucleons are exactly described by the $J$-pair approximation. If both $J=0$ and $J=2j$ pairing interactions are considered, the $J=2j$ pair truncation works very well in one of the two lowest $I=2j-1$ states. For six nucleons, $J$-pair approximations are very good for $J\sim 2j$, and the seniority scheme provides us with exact solutions to the $J=0$ pairing interaction.

The ${}^{12}$C(${}^{18}$O,${}^{16}$O)${}^{14}$C and ${}^{12,13}$C(${}^{18}$O,${}^{17}$O)${}^{13,14}$C reactions are studied at 84 MeV. Mass distributions and energy spectra of the ejectiles are measured, indicating the selectivity of these reactions to populate two- and one-neutron configurations in the states of the residual nucleus, respectively. The measured absolute cross-section angular distributions are analyzed by exact finite range coupled reaction channel calculations based on a parameter free double-folding optical potential. The form factors for the (${}^{18}$O,${}^{16}$O) reaction are extracted within an extreme cluster and independent particles scheme with shell-model-derived coupling strengths. The results show that the measured cross sections are accurately described for the first time without the need for any arbitrary scaling factor. The (${}^{18}$O,${}^{16}$O) reaction is thus found to be a powerful tool for quantitative spectroscopic studies of pair configurations in nuclear states.