The neutron capture cross sections of ${}^{74}\mathrm{Ge}$, ${}^{76}\mathrm{Ge}$, and ${}^{75}\mathrm{As}$ have been measured at the Karlsruhe Van de Graaff accelerator by means of the activation technique. The neutron source reaction ${}^7\mathrm{Li}(p,n){}^7\mathrm{Be}$ was used for simulating a thermal energy distribution for $\mathit{kT}=25$ keV to determine the astrophysically relevant stellar cross sections directly. Based on an extended series of activations, consistent results could be obtained, corresponding to Maxwellian average cross sections at $\mathit{kT}=30$ keV of $37.6\pm 3.9$ mb for ${}^{74}\mathrm{Ge}$, $21.5\pm 1.8$ mb for ${}^{76}\mathrm{Ge}$, and $362\pm 19$ mb for ${}^{75}\mathrm{As}$. These results are more accurate than previous data and are, therefore, important for resolving previous discrepancies. By extrapolation Maxwellian averaged cross sections were derived for thermal energies from 5 to 100 keV. The implications of these results for the $s$-process abundances in massive stars and for the background conditions in double $\beta$ decay experiments are discussed.

High spin states in neutron-deficient ${}^{106}\mathrm{In}$ were investigated using ${}^{78}\mathrm{Se}({}^{32}\mathrm{S},p3n)$ reaction at 125 MeV. The level scheme is extended up to 7 MeV of excitation energy for the negative parity states constituting four dipole bands, and the positive parity states which mainly exhibit single-particle excitations are extended up to 5 MeV. Projected deformed Hartree-Fock calculations were carried out to understand the configurations of different bands in this nucleus.

Isospin diffusion in semiperipheral collisions is probed as a function of the dissipated energy by studying two systems ${}^{58}\mathrm{Ni}+{}^{58}\mathrm{Ni}$ and ${}^{58}\mathrm{Ni}+{}^{197}\mathrm{Au}$, over the incident energy range $52A\text{−}74A$ MeV. A close examination of the multiplicities of light products in the forward part of the phase space clearly shows an influence of the isospin of the target on the neutron richness of these products. A progressive isospin diffusion is observed when collisions become more central, in connection with the interaction time.

We study isospin effects in semiperipheral collisions above the Fermi energy by considering the symmetric ${}^{58}\mathrm{Ni}+{}^{58}\mathrm{Ni}$ and the asymmetric ${}^{58}\mathrm{Ni}+{}^{197}\mathrm{Au}$ reactions over the incident energy range $52A\text{−}74A$ MeV. A microscopic transport model with two different parametrizations of the symmetry energy term is used to investigate the isotopic content of pre-equilibrium emission and the $N/Z$ diffusion process. Simulations are also compared to experimental data obtained with the INDRA array and provide information on the degree of isospin equilibration observed in $\mathrm{Ni}+\mathrm{Au}$ collisions. A better overall agreement between data and simulations is obtained when using a symmetry term that linearly increases with nuclear density.

Dilepton production in intermediate energy nucleus-nucleus collisions as well as in elementary proton-proton reactions is analyzed within the ultrarelativistic quantum molecular dynamics transport model. For $\mathrm{C}+\mathrm{C}$ collisions at $1A$ GeV and $2A$ GeV the resulting invariant mass spectra are compared to recent HADES data. We find that the experimental spectrum for $\mathrm{C}+\mathrm{C}$ at $2A$ GeV is slightly overestimated by the theoretical calculations in the region around the vector meson peak but fairly described in the low mass region, where the data are satisfactorily saturated by the Dalitz decay of the $\eta$ meson and the Δ resonance. At $1A$ GeV an underestimation of the experimental data is found, pointing that at lower energies the low-mass region is not fully saturated by standardly parametrized Δ Dalitz decays alone. Furthermore, predictions for dilepton spectra for $\mathit{pp}$ reactions at 1.25, 2.2, and 3.5 GeV and $\mathrm{Ar}+\mathrm{K}\mathrm{Cl}$ reactions at $1.75A$ GeV are presented. The study is complemented by a detailed investigation of the role of absorption of the parent particles on the corresponding dilepton yields in the regime that has so far been probed by HADES.

Differential cross sections for the reaction $\gamma p\to n{\pi }^{+}$ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.725 to 2.875 GeV. Where available, the results obtained here compare well with previously published results for the reaction. Agreement with the SAID and MAID analyses is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been made up to 2.7 GeV. Resonance couplings have been extracted and compared to previous determinations. With the addition of these cross sections to the world data set, significant changes have occurred in the high-energy behavior of the SAID cross-section predictions and amplitudes.

The soft-rotator model is applied to self-consistent analyses of the nuclear level structures and the nucleon interaction data of the even-even Sn isotopes, ${}^{116}\mathrm{Sn}$, ${}^{118}\mathrm{Sn}$, ${}^{120}\mathrm{Sn}$, and ${}^{122}\mathrm{Sn}$. The model successfully describes low-lying collective levels of these isotopes, which exhibit neither typical rotational nor harmonic vibrational structures. The experimental nucleon interaction data—total neutron cross sections, proton reaction cross sections, and nucleon elastic and inelastic scattering data—are well described up to 200 MeV in a coupled-channels optical model approach. For the calculations, nuclear wave functions for the Sn isotopes are taken from the nonaxial soft-rotator model with the model parameters adjusted to fit the measured low-lying collective level structures. We find that the ${\beta }_2$ and ${\beta }_3$ deformations for incident protons are larger than those for incident neutrons by $~15\%$, which is clear evidence of the deviation from the pure collective model for these isotopes.

We report the consequences of implementing momentum dependent interactions (MDI) on multifragmentation in heavy-ion reactions over entire collision geometry. The evolution of a single cold nucleus using static soft and soft momentum dependent equations of state demonstrates that inclusion of momentum dependence increases the emission of free nucleons. However, no heavier fragments are emitted artificially. The calculations performed within the framework of quantum molecular dynamics approach suggest that MDI strongly influence the system size dependence of fragment production. A comparison with ALADiN experimental data justifies the use of momentum dependent interactions in heavy-ion collisions.

Electromagnetic form factors of proton and neutron, obtained from a new fit of data, are presented. The proton form factors are obtained from a simultaneous fit to the ratio ${\mu }_p{G}_{\mathit{Ep}}/G_{\mathit{Mp}}$ determined from polarization transfer measurements and to $\mathit{ep}$ elastic cross section data. Phenomenological two-photon exchange corrections are taken into account. The present fit for protons was performed in the kinematical region $Q^2\in (0,6)$ ${\mathrm{GeV}}^2$. For both protons and neutrons we use the latest available data. For all form factors, the uncertainties and correlations of form factor parameters are investigated with the ${\chi }^2$ method.

Beam-recoil transferred polarizations for the exclusive $\overrightarrow{e}p\to e^{\text{'}}{K}^{+}\overrightarrow{\Lambda },{\overrightarrow{\Sigma }}^0$ reactions have been measured using the Continuous Electron Beam Accelerator Facility's large acceptance spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. New measurements have been completed at beam energies of 4.261 and 5.754 GeV that span a range of momentum transfer $Q^2$ from 0.7 to 5.4 ${\mathrm{GeV}}^2$, invariant energy $W$ from 1.6 to 2.6 GeV, and the full center-of-mass angular range of the $K^{+}$ meson. These new data add to the existing CLAS $K^{+}\Lambda$ measurements at 2.567 GeV, and provide the first-ever data for the $K^{+}{\Sigma }^0$ channel in electroproduction. Comparisons of the data with several theoretical models are used to study the sensitivity to $s$-channel resonance contributions and the underlying reaction mechanism. Interpretations within two semiclassical partonic models are made to probe the underlying reaction mechanism and the $s\overline{s}$ quark-pair creation dynamics.

$M1$ properties, comprising magnetic moments and radiative capture of thermal neutron observables, are studied in two- and three-nucleon systems. We use meson exchange current derived up to $\mathrm{N}{}^3\mathrm{LO}$ using heavy baryon chiral perturbation theory à la Weinberg. Calculations have been performed for several qualitatively different realistic nuclear Hamiltonians, which permits us to analyze model dependence of our results. Our results are found to be strongly correlated with the effective range parameters such as binding energies and the scattering lengths. Taking into account such correlations, the results are in good agreement with the experimental data with small model dependence.

Eight new isomeric states in neutron-rich nuclides have been discovered in fission fragments produced by the reaction of an 80 MeV/nucleon ${}^{238}\mathrm{U}$ beam with a ${}^9\mathrm{Be}$ target and separated in-flight using the A1900 fragment separator. The experiment was conducted at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. Gamma rays were detected in a high-purity germanium detector located at the focal plane within a time window of $20\hspace{0.5em}\mu$s following ion implantation. In some cases the isomers were observed to decay into previously reported states, allowing us to assign the initial decay from the isomeric state. Among the outcomes, the results suggest that many studies on the nuclear structure of medium-mass neutron-rich nuclei are feasible at projectile fragmentation facilities using induced fission.

The isotope ${}^{257}\mathrm{Rf}$ was produced in the fusion-evaporation reaction ${}^{208}\mathrm{Pb}({}^{50}\mathrm{Ti},n){}^{257}\mathrm{Rf}$. Reaction products were separated and identified by mass. Delayed spectroscopy of ${}^{257}\mathrm{Rf}$ and its decay products was performed. A partial decay scheme with configuration assignments is proposed based on $\alpha$ hindrance factors. The excitation energy of the $1/2^{+}[620]$ configuration in ${}^{253}\mathrm{No}$ is proposed. The energy of this $1/2^{+}$ state in a series of $N=151$ isotones increases with nuclear charge, reflecting an increase in the $N=152$ gap. This gap is deduced to grow substantially from 850 to 1400 keV between $Z=94$ and 102. An isomeric state in ${}^{257}\mathrm{Rf}$, with a half-life of ${160}_{-31}^{+42}\hspace{0.5em}\mu$s, was discovered by detecting internal conversion electrons followed by $\alpha$ decay. It is interpreted as a three-quasiparticle high-$K$ isomer. A second group of internal conversion electrons, with a half-life of $4.1_{-1.3}^{+2.4}$ s, followed by $\alpha$ decay, was also observed. These events might originate from the decay of excited states in ${}^{257}\mathrm{Lr}$, populated by electron-capture decay of ${}^{257}\mathrm{Rf}$. Fission of ${}^{257}\mathrm{Rf}$ was unambiguously detected, with a branching ratio of $b_{\mathrm{Rf}}^{\mathrm{SF}}=0.02\pm 0.01$.

We use diagrammatic perturbation theory to construct an effective shell-model operator for the neutrinoless double-$\beta$ decay of ${}^{82}\mathrm{Se}$. The starting point is the same Bonn-C nucleon-nucleon interaction that is used to generate the Hamiltonian for recent shell-model calculations of double-$\beta$ decay. After first summing high-energy ladder diagrams that account for short-range correlations and then adding diagrams of low order in the $G$ matrix to account for longer-range correlations, we fold the two-body matrix elements of the resulting effective operator with transition densities from the recent shell-model calculation to obtain the overall nuclear matrix element that governs the decay. Although the high-energy ladder diagrams suppress this matrix element at very short distances as expected, they enhance it at distances between one and two fermis, so that their overall effect is small. The corrections due to longer-range physics are large, but cancel one another so that the fully corrected matrix element is comparable to that produced by the bare operator. This cancellation between large and physically distinct low-order terms indicates the importance of a reliable nonperturbative calculation.

Full Faddeev-type calculations are performed for the breakup of ${}^{11}\mathrm{Be}$ on a proton target at 63.7 MeV/nucleon incident energy. A simplified two-body model for ${}^{11}\mathrm{Be}$ involves an inert ${}^{10}\mathrm{Be}(0^{+})$ core and a valence neutron. Inclusive cross sections as a function of the proton angle are calculated around the well known resonance at $E_r=1.275$ MeV including both resonant and nonresonant contributions. A reasonable agreement between the calculated angular distributions and the data is obtained but a large discrepancy relative to similar CDCC calculations is found at small proton angles.

Double-differential cross sections for light-ion ($p$, $d$, $t$, ${}^3\mathrm{He}$, and $\alpha$) production in carbon induced by 96 MeV neutrons have been measured at eight laboratory angles from ${20}^{°}$ to ${160}^{°}$ in steps of ${20}^{°}$. Experimental techniques are presented as well as procedures for data taking and data reduction. Deduced energy-differential, angle-differential, and production cross sections are reported. Experimental cross sections are compared with theoretical reaction model calculations and experimental data in the literature. The measured particle data show marked discrepancies from the results of the model calculations in spectral shape and magnitude. The measured production cross sections for protons, deuterons, tritons, ${}^3\mathrm{He}$, and $\alpha$ particles support the trends suggested by data at lower energies.

In ultrarelativistic heavy ion collisions, the multiplicity of multistrange baryons per participating nucleon increases with centrality in a different fashion for different systems and energies. At RHIC, for copper+copper (CuCu) collisions the increase is much steeper than for gold-gold ($\mathrm{Au}\mathrm{Au}$) collisions. We show that this system size dependence is due to a core-corona effect: the relative importance of the corona as compared to the core (thermalized matter) contribution varies and the contribution of a corona nucleon to the multiplicity differs from that of a core nucleon. ϕ mesons follow—as all hadrons—the same trend, but the difference between core and corona multiplicity is relatively small, and therefore the CuCu and $\mathrm{Au}\mathrm{Au}$ results are quite similar. This simple geometrical explanation makes also a strong case in favor of the validity of Glauber geometry in the peripheral regions of ultrarelativistic heavy ion collisions, which is crucial for understanding the early evolution of the system.

Self-consistent random phase approximation (RPA) approaches in the relativistic framework are applied to calculate the isospin symmetry-breaking corrections ${\delta }_c$ for the $0^{+}\to 0^{+}$ superallowed transitions. It is found that the corrections ${\delta }_c$ are sensitive to the proper treatments of the Coulomb mean field, but not so much to specific effective interactions. With these corrections ${\delta }_c$, the nucleus-independent $\mathcal{F}t$ values are obtained in combination with the experimental $\mathit{ft}$ values in the most recent survey and the improved radiative corrections. It is found that the constancy of the $\mathcal{F}t$ values is satisfied for all effective interactions employed. Furthermore, the element $V_{\mathit{ud}}$ and unitarity of the Cabibbo-Kobayashi-Maskawa matrix are discussed.

${}^{11}\mathrm{Be}+{}^{12}\mathrm{C}$ elastic-scattering data at 38.4 MeV/nucleon has been analyzed using the optical model. The optical potential is calculated in the framework of the double folding model using M3Y effective nucleon-nucleon interaction. Different models of ${}^{11}\mathrm{Be}$ density are tested and the model that does not include the halo structure gives poor fitting with data. The breakup effect is studied by introducing a complex dynamical polarization potential (DPP) that is added to the “bare” potential. The DPP is taken in different forms that have been obtained from simple phenomenological, semiclassical approximation, and microscopic methods. The simple phenomenological DPP is related to the semiclassical approximation method. The sensitivity of the differential and reaction cross sections to these polarization potentials is tested. The microscopic DPP that has been constructed from the derivative of the folding potential describes the breakup effect well. It gives an explicit justification for the long range of the polarization potential.

Recent relativistic mean-field calculations have provided nuclear distributions of Ca isotopes whose mass numbers are 60 through 74. We calculate observables of proton elastic scattering from these unstable isotopes and discuss relations between observables and nuclear distributions of such unstable nuclei. The calculations are based on relativistic impulse approximation (RIA) at incident proton energies from 100 through 500 MeV where predictions of RIA have been shown to provide good agreement with experimental data. To validate the use of optimal factorization and first-order calculations at these energies, contributions from the Fermi motion of the target nuclei and multiple scattering are estimated and compared with results calculated without these effects.