The $\gamma$ rays and conversion electrons emitted in the $\beta$ decay of ${}^{78}$Sr to levels in ${}^{78}$Rb have been studied using Ge detectors and a mini-orange spectrometer. A reliable level scheme based on the results of these experiments has been established. The properties of the levels in ${}^{78}$Rb have been compared with calculations based on deformed Hartree-Fock with Skyrme interactions and pairing correlations in the BCS approximation. This has allowed an interpretation of the nature of the observed sets of levels in the odd-odd nucleus ${}^{78}$Rb.

Energies of the lowest 4${}^{+}$ states in ${}^{10,12}$Be and ${}^{14,16}$C are examined in a simple model that works surprisingly well in three of the nuclei. The analysis suggests that three configurations are important for the first 4${}^{+}$ state in ${}^{10}$Be.

The $G$-parity-violating, second-class current- (SCC) induced tensor term in the weak-nucleon axial-vector current was determined from $\beta$-decay correlation measurements of the mass $A$ = 20 mirror pair. The alignment correlation terms in the $\beta$-decay angular distribution from the purely spin aligned mirror pair, ${}^{20}$F and ${}^{20}$Na, were measured in the present study. Combining the present results with existing results of $\beta$ and delayed $\gamma$-ray angular correlation measurements for the $A$ = 20 mirror pair, the SCC-induced tensor term was extracted to be $d_{\mathit{II}}/Ac$ = 0.18 $\pm$ 0.48. In the extraction, the weak-magnetism term, $b/Ac$ = 8.58 $\pm$ 0.28, evaluated from the $M$1 analog $\gamma$-ray decay strength, was used in a framework of the conserved vector current hypothesis. This is the first unambiguous extraction of the $(b-d_{\mathit{II}})/Ac$ term free from the contribution of the second-forbidden form factor, $j_2$, in the axial-vector current, which was a limiting factor for accurate determination of nonexistence of the SSC in the $\beta$ decay of the $A$ = 20 system.

A (${}^3\text{He},t$) charge-exchange reaction experiment on the double-beta decaying nucleus ${}^{136}$Xe has been performed at an incident energy of 420 MeV with the objective to measure the Gamow-Teller (GT) strength distribution in ${}^{136}$Cs. The measurements have been carried out at the dispersion-matched WS beam line and the Grand Raiden spectrometer of the Research Center for Nuclear Physics in Osaka, where an energy resolution of 42 keV was achieved. A new gas cell with thin windows made of polyethylene naphthalate has been employed as a target. The extracted GT strength distribution is confronted with the rather long $2\nu \beta \beta$ decay half-life of ${}^{136}$Xe.

Long-range contributions to the three-nucleon force that have recently been worked out in chiral effective-field theory at next-to-next-to-next-to-leading order are, for the first time, included in the triton and the doublet nucleon-deuteron scattering length calculations. The strengths of the two short-range terms available at this order in the chiral expansion are determined from the triton binding energy and the neutron-deuteron doublet scattering length. The structure of the resulting three-nucleon force is explored and effects for the two-nucleon correlation function in the triton are investigated. Expectation values of the individual contributions to the three-nucleon force in the triton are found to be in the range of a few hundred kilo–electron volts to about 1 MeV. Our study demonstrates that the very complicated operator structure of the novel chiral three-nucleon forces can be successively implemented in three-nucleon Faddeev calculations.

We study nuclear medium effects in the weak structure functions $F_2(x,Q^2)$ and $F_3(x,Q^2)$ in the deep inelastic neutrino and antineutrino induced reactions in nuclei. We use a theoretical model for the nuclear spectral functions which incorporates the conventional nuclear effects, such as Fermi motion, binding, and nucleon correlations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. The calculations have been performed using relativistic nuclear spectral functions. Our results are compared with the experimental data of the NuTeV and the CERN Dortmund Heidelberg Saclay Warsaw (CDHSW) collaborations.

Elastic scattering data for ${}^{141}$Pr($\alpha ,\alpha$)${}^{141}$Pr have been analyzed to derive a new energy-dependent local potential for the ${}^{141}$Pr-$\alpha$ system. This potential is used successfully to predict the cross section of the ${}^{141}$Pr($\alpha ,n$)${}^{144}$Pm reaction at low energies where new experimental data have become available very recently. In contrast to various global potentials, this new potential is able to reproduce simultaneously elastic scattering data around and above the Coulomb barrier and reaction data below the Coulomb barrier for the ${}^{141}$Pr-$\alpha$ system. Reasons for the partial failure of the global potentials are explained by intrinsic properties of the scattering matrix and their variation with energy. The new local potential may become the basis for the construction of a new global $\alpha$-nucleus potential.

Inelastic scattering from ${}^{12}$C has been measured at extremely forward angles including 0 ${}^{\circ }$ using 386 MeV $\alpha$ particles to study the $\alpha$-cluster states around $E_x$ $\sim$ 10 MeV, especially the 2${}^{+}$ state predicted by the $\alpha$-cluster model. We have analyzed ($\alpha$,${\alpha }^{\prime }$) cross-section data using both peak-fitting and multipole decomposition techniques. A 2${}^{+}$ state at $E_x=$ 9.84 $\pm$ 0.06 MeV with a width of 1.01 $\pm$ 0.15 MeV is found to be submerged in the broad 0${}^{+}$ state at $E_x=$ 9.93 $\pm$ 0.03 MeV with a width of 2.71 $\pm$ 0.08 MeV. This 2${}^{+}$ state may be interpreted as the 2${}^{+}$ excitation of the Hoyle state and the $\alpha$-condensate state.

Although ab initio calculations of relativistic Brueckner theory lead to large scalar isovector fields in nuclear matter, at present, successful versions of covariant density functional theory neglect the interactions in this channel. A new high-precision density functional DD-ME$\delta$ is presented which includes four mesons, $\sigma$, $\omega$, $\delta$, and $\rho$, with density-dependent meson-nucleon couplings. It is based to a large extent on microscopic ab initio calculations in nuclear matter. Only four of its parameters are determined by adjusting to binding energies and charge radii of finite nuclei. The other parameters, in particular the density dependence of the meson-nucleon vertices, are adjusted to nonrelativistic and relativistic Brueckner calculations of symmetric and asymmetric nuclear matter. The isovector effective mass $m_p^{*}-m_n^{*}$ derived from relativistic Brueckner theory is used to determine the coupling strength of the $\delta$ meson and its density dependence.

The longitudinal long-range correlations of the triangular flow event-plane angles are calculated in a Boltzmann + hydrodynamics hybrid approach. The potential to disentangle different energy deposition scenarios is explored by utilizing two different transport approaches for the early nonequilibrium evolution. In the hadronic transport approach the particle production in high-energy heavy ion reactions is mainly governed by string excitation and fragmentation processes which are absent in the parton cascade approach. We find that in both approaches the initial state shows a strong longitudinal correlation of the event-plane angles which is diluted but still persists in the final state momentum space distributions of the produced particles. The observation of this effect is an important prerequisite for the experimental determination of odd harmonics that relies on a rapidity independent event-plane definition.

We investigate microscopic self-organization processes of nuclear matter in the outermost layers of neutron star crusts with the DYWAN model. In this framework a pure mean-field description of nuclear dynamics has been performed. Starting from initial crystalline lattices, which are expected in the most external regions, the system organizes itself in exotic structures. The present work focuses on the effects of both the initial lattice symmetries and the nuclear species on the morphology and on the evolution of those structures. The response of the system is analyzed when it is subjected to random fluctuations of the initial lattice.

The ($n,\gamma$) cross section of ${}^{96}$Zr has been investigated at the CERN n_TOF spallation neutron source. High-resolution time-of-flight measurements using an enriched ZrO${}_2$ sample allowed us to analyze 15 resonances below 40 keV with improved accuracy. On average, the capture widths were found to be 25% smaller than reported in earlier experiments. If complemented with the contribution by direct radiative capture, the derived Maxwellian averaged cross sections are consistent with activation data at $kT=25$ keV. The present results confirm the astrophysical implications for the $s$-process branching at ${}^{95}$Zr.

We have measured the total cross section for production of $e^{+}{e}^{-}$ pairs by photons in the Coulomb field of Ge nuclei. Up to 10${}^{16}$ $\gamma$ quanta per second were produced by thermal-neutron capture reactions of a natural gadolinium target, placed inside the high-flux reactor of the ILL Grenoble. Out of this stream of $\gamma$ rays various strong discrete $\gamma$ lines were extracted using the GAMS5 Bragg spectrometer of the ILL. A well-collimated beam of reflected $\gamma$ rays irradiated a germanium detector placed inside an anti-Compton shield, consisting of eight bismuth germanate crystals, assembled as a pair spectrometer. Using this new technique we have measured, for the first time, the pair production cross section at only 18.2 keV above the 1022-keV threshold. Our measurements indicate that the pair production cross section, expressed in units of Bethe-Heitler, grows monotonously toward low energies and does not support the claim of other works of a maximum at $\sim$65 keV.

Collisions of deformed uranium nuclei provide a unique opportunity to study the spatial dependence of charmonium in-medium effects. By selecting the orientations of the colliding nuclei, different path lengths through the nuclear medium could be selected within the same experimental environment. In addition, higher energy densities can be achieved in U + U collisions relative to Au+Au collisions. In this paper, we investigate the prospects for charmonium studies with U + U collisions. We discuss the effects of shadowing and nuclear absorption on the $J/\psi$ yield. We introduce a new observable which could help distinguish between different types of $J/\psi$ interactions in hot and dense matter.

Relativistic mean-field calculations were performed for a number of nuclei in the mass $A\sim 80$ region. Ground-state binding energy, charge radius, and charge density values were compared with experiment. The optical potential was generated folding the nuclear density with the microscopic nuclear interaction DDM3Y. $S$ factors for low-energy ($p,\gamma$) and ($p,n$) reactions were calculated and compared with experiment.

With the help of the radial basis function (RBF) and the Garvey-Kelson relation, the accuracy and predictive power of some global nuclear mass models are significantly improved. The rms deviation between predictions from four models and 2149 known masses falls to $\sim$200 keV. The AME95-03 and AME03-Border tests show that the RBF approach is a very useful tool for further improving the reliability of mass models. Simultaneously, the differences from different model predictions for unknown masses are remarkably reduced and the isospin symmetry is better represented when the RBF extrapolation is combined.

Within the complex-energy configuration-interaction framework, we study correlations of valence neutrons to explain the behavior of charge radii in neutron halo nuclei ${}^{6,8}$He. We find that the experimentally observed decrease of the charge radius between ${}^6$He and ${}^8$He is caused by a subtle interplay between three effects: dineutron correlations, a spin-orbit contribution to the charge radius, and a core swelling effect. We demonstrate that two-neutron angular correlations in the $2_1^{+}$ resonance of ${}^6$He differ markedly from the ground-state correlations in ${}^{6,8}$He. Finally, we discuss the impact of the neutron threshold position and valence neutron correlation energy on the neutron radius, i.e., the pairing-antihalo effect.

We compute a model-independent correlation between the difference of neutron-neutron and proton-proton scattering lengths, $|a_{nn}-a_{pp}^C|$, and the splitting in binding energies between helium-3 and tritium nuclei. We use the effective field theory without explicit pions to show that this correlation relies only on the existence of large scattering lengths in the NN system. Our leading-order calculation, taken together with experimental values for binding energies and $a_{pp}^C$, yields $a_{nn}=-22.9\pm 4.1$fm.

Short-range correlations between nucleon pairs in different spin-isospin channels are investigated for light nuclei using the Argonne $v{8}^{\prime }$ interaction. At distances below 1 fm a universal behavior is found for the deuteron, ${}^3$H, ${}^3$He, and for ground and first excited states in ${}^4$He. This behavior in coordinate space is reflected by a universal behavior for the high-momentum components in momentum space. The universality indicates that a pairwise renormalization is possible in order to obtain a universal effective two-body interaction that does not scatter to high-momentum states. The exact two-body densities are compared with those obtained using the unitary correlation operator method with simple trial wave functions. The effect of three-body correlations due to the tensor force on the two-body densities is discussed.