The yrast level structure of ${}^{215}$Rn has been studied by means of in-beam spectroscopy $\alpha$-$\gamma$-$\gamma$ coincidence techniques through the ${}^{207}$Pb(${}^{18}$O,2$\alpha 2n$) reaction at 93 MeV bombarding energy, using the 8$\pi$ GASP-ISIS spectrometer at Legnaro. New spectroscopic information has been obtained. The deduced low-lying level scheme of ${}^{215}$Rn does not exhibit the alternating parity structure observed in the heavier known isotones ${}^{216}$Fr, ${}^{217}$Ra, ${}^{218}$Ac, and ${}^{219}$Th. From this result, the lightest nucleus showing evidence for octupole collectivity is ${}^{216}$Fr, defining the lowest-mass corner for this kind of phenomenon as $N\ge 129$ and $Z\ge 87$.

The $\alpha$-particle energy spectra have been measured in coincidence with fission fragments (FFs) in the ${}^{12}$C (69 MeV)+${}^{232}$Th reaction at various relative angles with respect to FF direction. The spectra were fitted with a moving-source model calculation to extract the multiplicities corresponding to different emission stages of the fusion-fission process. The fitted value for the near-scission emission component appears anomalously enhanced in comparison to the recently developed systematics for prescission and near-scission $\alpha$-particle multiplicities in heavy-ion reactions. A high-energy component corresponding to the summed energy of two $\alpha$ particles is observed, which suggests breakup of ${}^8$Be into two $\alpha$ particles in $\alpha$-transfer-induced fission coincidence events. The ${}^8$Be breakup fits the 2$\alpha$-particle multiplicity spectra very well at different laboratory angles. When ${}^8$Be breakup is included exclusively as a source of $\alpha$-particle emission in the moving-source analysis along with prescission, postscission, and near-scission emission, the results follow the systematics of heavy-ion data very well. The present results clearly indicate an extra source of $\alpha$-particle emission due to ${}^8$Be breakup in $\alpha$-transfer-induced fission reactions.

Odd-even staggering effects on charge distributions are investigated for fragments produced in semiperipheral and central collisions of ${}^{112}\text{Sn}+{}^{58}\text{Ni}$ at 35 MeV/nucleon. For fragments with $Z\le 16$ one observes a clear overproduction of even charges, which decreases for heavier fragments. Staggering persists up to $Z\sim 30$. The staggering appears to be substantially independent of the centrality of the collisions, suggesting that it is mainly related to the last few steps in the decay of hot nuclei.

The EUROGAM-2 array has been used to study $\gamma$ rays emitted following the spontaneous fission of a ${}^{248}$Cm source. Analysis of Doppler-broadened lineshapes corresponding to transitions from excited rotational states in neutron-rich Sr, Zr, Mo, Ru, and Pd fission fragments has enabled measurements of state lifetimes in these nuclei at nuclear spins of $I\sim 10$. Extracted transition quadrupole moments are compared with various recent theoretical approaches, as well as with measurements at lower spin, and an interpretation of the data is made within the context of prolate-oblate shape competition in this region.

A systematic study of 160 heavy and superheavy nuclei is performed in the Hartree-Fock-Bogoliubov (HFB) approach with the finite-range and density-dependent Gogny force with the D1S parameter set. We show calculations in several approximations: with axially symmetric and reflection-symmetric wave functions, with axially symmetric and non-reflection-symmetric wave functions, and finally with some representative triaxial wave functions. Relevant properties of the ground state and along the fission path are thoroughly analyzed. Fission barriers, $Q_{\alpha }$ factors, and lifetimes with respect to fission and $\alpha$ decay as well as other observables are discussed. Larger configuration spaces and more general HFB wave functions as compared to previous studies provide a very good agreement with the experimental data.

High-spin states in the odd-odd ${}^{174}$Re have been investigated via the ${}^{152}$Sm(${}^{27}$Al, 5$\mathit{\text{n}}\gamma$)${}^{174}$Re reaction with the help of excitation function, x-$\gamma$, and $\gamma -\gamma$ coincidence measurements. Five rotational bands have been observed and their configurations were assigned based on alignments, band crossing frequencies, electromagnetic properties, and the estimated bandhead excitation energies. Low-spin signature inversion has been identified in the two-quasiparticle bands built on $\pi h_{11/2}\otimes \nu i_{13/2}$, $\pi h_{9/2}\otimes \nu i_{13/2}$, and $\pi 1/2^{-}\left[541\right]\otimes \nu 5/2^{-}\left[512\right]$ configurations. $E2$ interband transitions were analyzed with band-mixing calculations giving information on shapes and shape driving effects for the bands of interest.

Nuclear structure quantum Monte Carlo methods such as Green's function or auxiliary field diffusion Monte Carlo have used phenomenological local real-space potentials containing as few derivatives as possible, such as the Argonne-Urbana family of interactions, to make sampling simple and efficient. Basis set methods such as no-core shell model and coupled-cluster techniques typically use softer non-local potentials because of their more rapid convergence with basis set size. These non-local potentials are usually defined in momentum space and are often based on effective field theory. Comparisons of the results of the two types of methods can be difficult when different potentials are used. We show methods for evaluating the real-space imaginary-time propagators needed to perform quantum Monte Carlo calculations using such non-local potentials. We explore the universality of the large imaginary time propagators for different potentials and discuss how non-local potentials can be used in quantum Monte Carlo calculations.

Background: The total inclusive cross sections obtained for quasielastic (QE) scattering in the Mini Booster Neutrino Experiment (MiniBooNE) are significantly larger than those calculated by all models based on the impulse approximation and using the world average value for the axial mass of $M_A\approx 1\mathrm{GeV}$. This discrepancy has led to various, quite different explanations in terms of increased axial masses, changes in the functional form of the axial form factor, increased vector strength in nuclei, and initial two-particle interactions. This is disconcerting since the neutrino energy reconstruction depends on the reaction mechanism.

Purpose: We investigate whether exclusive observables, such as nucleon knockout, can be used to distinguish between the various proposed reaction mechanisms. We determine the influence of 2p-2h excitations on the neutrino energy reconstruction.

Method: We extend the Giessen Boltzmann–Uehling–Uhlenbeck (GiBUU) model by explicitly incorporating initial 2p-2h excitations.

Results: We calculate inclusive cross sections and numbers and spectra of knockout nucleons and show their sensitivity to the presence of 2p-2h initial excitations. We also discuss the influence of 2p-2h excitations on the neutrino energy reconstruction.

Conclusions: Inclusive double-differential cross sections, depending only on muon variables, are fairly insensitive to the reaction mechanism. 2p-2h excitations lead to an increase in the number $n$ of knockout nucleons for $n⩾2$, while only the $n=1$ knockout remains a clean signal of true QE scattering. The spectra of knockout nucleons are also changed, but their shape is hardly affected. In the energy reconstruction, 2p-2h interactions as well as $\Delta$ excitations lead to a downward shift of the reconstructed energy; this effect of 2p-2h excitations disappears at higher energies because the 2p-2h influence is spread out over a wider energy range.

Magnetic hyperfine field at Cu isotopes as impurities in Fe were recently measured at low temperature. A model to explain these experimental results is proposed. The diluted Cu impurities in the ferromagnetic Fe host are described by an extension of the Daniel-Friedel model, including the next neighbor perturbation. In order to account for the available experimental data in Cu isotopes with atomic masses $A$ $=$ 59, 67, 69, and 71 as impurity, we needed to incorporate the Cu anomaly volume in the effective charge to be screened and self-consistent procedures.

High-spin states in ${}^{126}$I have been investigated by using in-beam $\gamma$-ray spectroscopy with the ${}^{124}$Sn(${}^7\text{Li},5n$)${}^{126}$I reaction at a beam energy of 48 MeV. The level scheme of ${}^{126}$I has been extended and modified considerably by adding about 80 new $\gamma$ rays and establishing five new bands. The configurations have been tentatively assigned for the yrast, yrare, and other excited bands with the help of triaxial projected shell-model (TPSM) and cranked shell-model calculations. The first band crossing in the yrast band is found due to alignments of a pair of ${\left(h_{11/2}\right)}^2$ neutrons. The first and the second band crossings in the yrare band are caused by the alignments of a pair of ${\left(d_{5/2}\right)}^2$ protons and a pair of ${\left(h_{11/2}\right)}^2$ neutrons, respectively. Due to the successive excitations of two, four, and six quasiparticles, the alignments in the yrare band present a gigantic rising feature. The yrast band exhibits a signature inversion at low spins and becomes normal after a reversion spin of $I_{\mathrm{rev}}=14$. The yrare band exhibits an abnormal signature inversion in which the signature inversion phase persists up to the highest spin. The signature inversions in ${}^{126}$I are well reproduced and successfully interpreted by the TPSM calculations. Some features of chirality are found for the four-quasiparticle (4qp) part of the yrast band and the 4qp excited band 2.

Radioactive isotopes of beryllium to phosphorus were produced by projectile fragmentation of an ${}^{40}$Ar beam with either a Be, Ni, or Ta target at the National Superconducting Cyclotron Laboratory. The fragmentation cross sections, parallel momentum transfers, and widths were systematically measured and compared to the empirical parametrization of epax and to predictions from internuclear cascade and deep inelastic codes. The predicted distributions for the widths from the internuclear cascade simulations agree to within one standard deviation with the measured results, whereas the velocities and cross sections are found to be more consistent with the deep-inelastic-transfer calculations. A target dependence was found in the reaction cross sections for the neutron-rich nuclei with the largest $N/Z$, suggesting an enhancement in the fragment yields larger $N/Z$ targets.

The dynamical cluster-decay model (DCM), a nonstatistical description developed by Gupta and collaborators to account for the decay studies of excited compound nuclei formed in low-energy reactions has been applied to study various reactions. One of the main ingredient of the model is the use of temperature-dependent binding energies. In the present work, the effect of temperature-dependent binding energies in the model is analyzed. In earlier works on the DCM, the temperature-dependent liquid drop energy from Davidson et al.'s work [N. J. Davidson, S. S. Hsiao, J. Markram, H. G. Miller, and Y. Tzeng, Nucl. Phys. A 570, 61 (1994)], with two of its constants refitted for each isotopic chain to reproduce ground-state experimental binding energies, is used. In this work, the temperature-dependent binding energy formulas of Krappe [H. J. Krappe, Phys. Rev. C 59, 2640 (1999)] and Guet et al. [C. Guet, E. Strumberger, and M. Brack, Phys Lett. B 205, 427 (1988)] are used in the DCM without any refitting of the coefficient of the liquid drop needed to study the decay of the hot and rotating ${}^{56}{\mathrm{Ni}}^{*}$ system formed in the ${}^{32}\mathrm{S}+{}^{24}\mathrm{Mg}$ reaction at two incident energies, $E_{\mathrm{c}.\mathrm{m}.}=51.6$ and 60.5 MeV. The use of Krappe's formula results in the explicit preference of a four-nucleon transfer, indicating a strong minima in the potential energies corresponding to $\alpha$-structured nuclei as well as exhibiting structural effects in the preformation calculations favoring $\alpha$-structured nuclei. The overall cross sections for the light particles and intermediate mass fragments are nicely reproduced by the use of Krappe's formula. However, the individual channel cross-sections exhibit a strong distribution only for $\alpha$ nuclei, and for other fragments the results are lower by a factor of 2 to 3. The use of Guet et al.'s formula though does not show any explicit structure effects in the potential energy calculations or the preformation calculations; the overall cross sections calculated for light particles and intermediate mass fragments compare well with the experimental data. The results of individual channel cross-sections, however, do not exhibit any explicit preference for the $\alpha$-structured nuclei; rather, the individual channel cross sections decreases with an increase in the mass number of the fragments. The calculated average kinetic energies using both formulas for the favored $\alpha$ fragments compares well with experimental values. Without any refitting of the coefficients of the temperature-dependent binding energies, the DCM works out well and the explicit preference of $\alpha$ structure depends mainly on the choice of formula used.

We propose a model of the nucleon in which quark-diquark configurations immersed in a pion cloud are treated in a manner consistent with Poincaré invariance. With suitably chosen parameters, the computations employing this model reproduce the measured electromagnetic form factors and the quark-spin contribution to the total nucleon angular momentum.

We have performed measurements of scintillation light in liquid neon, observing a signal yield in our detector as high as (3.5 $\pm$ 0.4) photoelectrons/keV. We measure pulse shape discrimination efficiency between electronic and nuclear recoils in liquid neon from 50 to 300 keV nuclear recoil energy. We also measure the ${\mathcal{L}}_{\mathrm{eff}}$  parameter in liquid neon between 30 and 370 keV nuclear recoil energy, observing an average ${\mathcal{L}}_{\mathrm{eff}}$$=0.24$ above 50 keV. We observe a dependence of the scintillation time distribution and signal yield on the pressure and temperature of the liquid neon.

Using quasimonochromatic laser-Compton scattering $\gamma$ rays, total photoneutron cross sections were measured for ${}^{206,207,208}$Pb near neutron threshold with a high-efficiency 4$\pi$ neutron detector. Partial $E1$ and $M1$ photoneutron cross sections along with total cross sections were determined for ${}^{207,208}$Pb at four energies near threshold by measuring anisotropies in photoneutron emission with linearly polarized $\gamma$ rays. The $E1$ strength dominates over the $M1$ strength in the neutron channel where $E1$ photoneutron cross sections show extra strength of the pygmy dipole resonance in ${}^{207,208}$Pb near the neutron threshold corresponding to 0.32$\%$–0.42$\%$ of the Thomas-Reiche-Kuhn sum rule. Several ${\mu }_N^2$ units of $B\left(M1\right)\uparrow$ strength were observed in ${}^{207,208}$Pb just above neutron threshold, which correspond to an $M1$ cross section less than 10$\%$ of the total photoneutron cross section.

The reformulated coupled-cluster method (CCM), in which average many-body potentials are introduced, provides a useful framework to organize numerous terms appearing in CCM equations, which enables us to clarify the structure of the CCM theory and physical importance of various terms more easily. We explicitly apply this framework to ${}^4$He, retaining one-body and two-body correlations as the first illustrating attempt. Numerical results with using two modern nucleon-nucleon interactions (AV18 and CD-Bonn) and their low-momentum interactions are presented. The characters of short-range and many-body correlations are discussed. Although not considered explicitly, the expression of the ground-state energy in the presence of a three-nucleon force is given.

The four-proton hole ${}^{96}\mathrm{Pd}$ neighbor of the doubly-magic ${}^{100}\mathrm{Sn}$ nucleus was studied in-beam, using a fusion-evaporation reaction of a ${}^{58}\mathrm{Ni}$ beam on a ${}^{45}\mathrm{Sc}$ target. States of ${}^{96}\mathrm{Pd}$ were established up to an excitation energy of 9707 keV. A core-excited odd-parity isomer with $T_{1/2}=37.7\left(1.1\right)$ ns was identified. Shell model calculations were performed in four different model spaces. Even-parity states of ${}^{96}\mathrm{Pd}$ are very well reproduced in large-scale shell model (LSSM) calculations in which excitations are allowed of up to five $g_{9/2}$ protons and neutrons across the $N=Z=50$ gap, to the $g_{7/2}$, $d_{5/2}$, $d_{3/2}$, and $s_{1/2}$ orbitals. The odd-parity isomer can be only qualitatively interpreted though, employing calculation in the full $fpg$ shell model space, with just one particle-hole core excitation.

The electromagnetic dipole strength of the nucleus ${}^{136}$Ba has been investigated. Two measurements were performed with electron energies of 7.0 and 11.4 MeV at the bremsstrahlung facility at the ELBE accelerator of the Helmholtz-Zentrum Dresden-Rossendorf. Photon scattering experiments on the same nucleus have been performed at the high-intensity gamma-ray source (HI$\gamma$S) facility of the Triangle Universities Nuclear Laboratory between 4.7 and 9.3 MeV. The geant4 code has been used to determine detector response and non-nuclear scattered events. Thus it is possible to account for the dipole strength in the quasicontinuum of unresolvable transitions. A statistical code was used to simulate inelastic transitions and to determine the branching ratios of transitions to the ground state. The resulting photoabsorption cross section is compared to quasiparticle random-phase approximation and relativistic quasiparticle time blocking approximation calculations.

Background: To understand explosive hydrogen burning in stars and to explore various explosive scenarios such as type I x-ray bursts (XRBs), reliable reaction rates are needed. The cross sections for radiative proton capture on near-dripline nuclei are necessary for the determination of the reaction rates, but cannot be measured directly.

Purpose: To determine the reaction rate for the radiative proton capture reaction ${}^{23}\mathrm{Al}{(p,\gamma )}^{24}\mathrm{Si}$ using indirect methods and, as a consequence, evaluate if sequential $2p$ capture on ${}^{22}$Mg seed nuclei is significant at high temperatures.

Method: Nonresonant radiative proton capture on ${}^{23}$Al is investigated using the one-proton breakup of ${}^{24}$Si at 61  MeV/nucleon and the asymptotic normalization coefficient (ANC) for ${}^{24}{\mathrm{Si}}_{\mathrm{gs}}\to {}^{23}\mathrm{Al}+p$ is deduced.

Results: From the ANC, the nonresonant component of the astrophysical $S$-factor for the ${}^{23}\mathrm{Al}{(p,\gamma )}^{24}\mathrm{Si}$ reaction is determined and, using other new experimental data the resonant component is re-evaluated.

Conclusions: The ${}^{23}\mathrm{Al}{(p,\gamma )}^{24}\mathrm{Si}$ reaction is of interest for type I XRB nucleosynthesis and its reaction rate can affect both the ${}^{22}$Na abundance and the total energy output. New determinations of the rates for the ${}^{22}\mathrm{Mg}{(p,\gamma )}^{23}\mathrm{Al}{(p,\gamma )}^{24}\mathrm{Si}$ reaction chain are provided here and we point to the need that they be included in XRB scenarios.

Recently a generalized density matrix (GDM) procedure was proposed [Jia and Zelevinsky, Phys. Rev. C 84, 064311 (2011)] for calculating a collective/bosonic Hamiltonian microscopically from the shell-model Hamiltonian. In this work we examine the validity of the method by comparing the GDM results with those of the exact shell-model diagonalization in a number of models. It is shown that the GDM method reproduces the low-lying collective states quite well, both for energies and transition rates, across the whole region going from vibrational to $\gamma$-unstable and deformed nuclei.