We propose a new method for measuring longitudinal amplitudes for electroproduction of pseudoscalar mesons that exploits a symmetry relation for polarization observables in parallel kinematics. This polarization technique does not require variation of electron scattering kinematics and avoids the major sources of systematic errors in Rosenbluth separation.

We use our standard self-consistent Thomas-Fermi model of nuclei to calculate the neutron and proton densities, from which we deduce the associated potential wells. We do this for the equilibrium densities as well as for the nonequilibrium densities with larger or smaller diffusenesses. This makes it possible to correlate the changes in the potential-well diffusenesses with the energy cost in going away from the optimum values. These and other properties of the Thomas-Fermi potential wells are tabulated for nuclei with mass numbers $A=20\mathrm{}$ to $A=340\mathrm{}$ along the valley of stability, as well as for neutron-rich or neutron-deficient isotopes. The results are represented by polynominal fits that may be used in macroscopic-microscopic studies of the surface diffuseness degrees of freedom.

Adiabatic nucleon-nucleon potentials are calculated in a six-quark nonrelativistic chiral constituent quark model where the Hamiltonian contains a linear confinement and a pseudoscalar meson (Goldstone boson) exchange interaction between quarks. Calculations are performed both in a cluster model and a molecular orbital basis, through coupled channels. In both cases the potentials present an important hard core at short distances, explained through the dominance of the $[51{]}_{\mathrm{FS}}$ configuration, but do not exhibit an attractive pocket. We add a scalar meson exchange interaction and show how it can account for some middle-range attraction.

We have examined the importance of momentum-dependent-induced nucleon currents such as weak-magnetism and pseudoscalar couplings to the amplitude of neutrinoless double beta decay $(0\mathrm{}\nu \beta \beta$ decay) in the mechanisms of light and heavy Majorana neutrino, as well as in that of Majoron emission. Such effects are expected to occur in all nuclear models in the direction of reducing the light neutrino matrix elements by about $30\%.$ To test this we have performed a calculation of the nuclear matrix elements of the experimentally interesting nuclei $A=76,\hspace{0.5em}82,\hspace{0.5em}96,\hspace{0.5em}100,\hspace{0.5em}116,\hspace{0.5em}128,\hspace{0.5em}130,\hspace{0.5em}136,$ and 150 within the proton-neutron renormalized quasiparticle random-phase approximation. We have found that indeed such corrections vary somewhat from nucleus to nucleus, but in all cases they are greater than $25\%.$ In the case of a heavy neutrino the effect is much larger (up to a factor of 6). Combining our results with the best presently available experimental limits on the half-life of the $0\nu \beta \beta$ decay, we have extracted new limits on the effective neutrino mass (light and heavy) and the effective Majoron coupling constant.

Cranked relativistic Hartree-Bogoliubov (CRHB) theory is presented as an extension of relativistic mean field theory with pairing correlations in the rotating frame. Pairing correlations are taken into account by a finite range two-body force of Gogny type, and approximate particle number projection is performed by the Lipkin-Nogami method. This theory is applied to the description of yrast superdeformed rotational bands observed in even-even nuclei of the $A\sim 190$ mass region. Using the well-established parameter sets NL1 for the Lagrangian and D1S for the pairing force one obtains a very successful description of data such as kinematic ${(J}^{\mathrm{}\left(1\right)\mathrm{}})$ and dynamic ${(J}^{\mathrm{}\left(2\right)\mathrm{}})$ moments of inertia without any adjustment of new parameters. Within the present experimental accuracy the calculated transition quadrupole moments $Q_t$ agree reasonably well with the observed data.

Angular distributions of Xe fragments produced in peripheral collisions of a ${}^{136}$Xe beam (700 MeV/nucleon) with ${}^{208}$Pb and ${}^{\mathrm{nat}}$Sn targets were measured. Equivalent sharp-cutoff minimum impact parameters were derived on the basis of a semiclassical description for the electromagnetic excitation of one- and two-phonon giant resonances. The results are compared with current standard parametrizations of minimum impact parameters and with the soft-spheres model using realistic mass density distributions for projectile and targets.

We present predictions for the formation of (anti)nuclear bound states in nucleus-nucleus reactions at ultrarelativistic energies. The phase-space coalescence method is used in combination with RQMD v2.4 transport calculations to demonstrate the relevance of particle production, as well as the longitudinal and transverse flow components. The formation of deuterons follows an approximate scaling law proportional to the relative freeze-out densities of nucleons and produced secondaries. For antideuterons, an additional suppression appears that is proportional to the number of nucleons, pointing toward multiple rescattering and absorption prior to freeze out.

The $B\left(E2\mathrm{}\right)\mathrm{}$ values for several critical transitions in ${}^{152}\mathrm{Sm}$ are determined following the $\epsilon$ decay of ${}^{152}\mathrm{Eu}.$ These data improve upon and correct previous studies and allow us to perform a full analysis of phase coexistence in ${}^{152}\mathrm{Sm},$ to analyze the mixing found empirically, and to compare this with detailed model calculations.

The cross sections for electron-induced two-nucleon knockout reactions are evaluated for the example of the ${}^{16}\mathrm{O}{(e,e}^{\prime }{pn)}^{14}\mathrm{N}$ reaction leading to discrete states in the residual nucleus ${}^{14}\mathrm{N}.$ These calculations account for the effects of nucleon-nucleon correlations and include the contributions of two-body meson exchange currents as the pion seagull, pion in flight, and the isobar current contribution. The effects of short-range as well as tensor correlations are calculated within the framework of the coupled cluster method employing the Argonne V14 potential as a model for a realistic nucleon-nucleon interaction. The relative importance of correlation effects as compared to the contribution of the meson exchange currents depends on the final state of the residual nucleus. The cross section leading to specific states, such as, e.g., the ground state of ${}^{14}\mathrm{N},$ is rather sensitive to the details of the correlated wave function.

The total average spins of fission fragments were measured as a function of fragment mass in ${}^{12}\mathrm{C},$ ${}^{16}\mathrm{O}{+}^{209}\mathrm{Bi}$ and ${}^{12}\mathrm{C},$ ${}^{16}\mathrm{O}{+}^{232}\mathrm{Th}$ reactions at bombarding energies near and above the Coulomb barrier. The mass dependence of the fragment spin for the ${}^{12}\mathrm{C},$ ${}^{16}\mathrm{O}{+}^{232}\mathrm{Th}$ reactions is observed to be in marked contrast to that for the ${}^{12}\mathrm{C},$ ${}^{16}\mathrm{O}{+}^{209}\mathrm{Bi}$ reactions. The present results have been analyzed within the framework of the statistical model taking into account the finite relaxation times for the equilibration of the collective-spin modes. The observed features in ${}^{12}\mathrm{C},$ ${}^{16}\mathrm{O}{+}^{232}\mathrm{Th}$ reactions can be ascribed to incomplete equilibration of the collective-spin modes where the mass relaxation at extreme mass asymmetries terminates before full statistical equilibration of the collective-spin modes is reached.

The absorption of positive pions on N and Ar has been studied for $T_{{\pi }^{+}}=118,$ 162, and 239 MeV. A precise determination has been made of the total absorption cross section for each energy and target nucleus. Comparisons are made with prior LADS results on ${}^2\mathrm{H},$ ${}^3\mathrm{He},$ and ${}^4\mathrm{He}.$ In addition, results are presented for the detected multiplicities of emitted protons, neutrons, and deuterons following pion absorption.

We present an alternative method for calculating amplitudes for correlated ππ exchange in the “σ” and ρ channel in $\pi N$ scattering. Starting from a fixed mass meson exchange potential, we introduce the width of the exchanged particles by integrating over a mass spectral function. The spectral functions are constructed from the pseudoempirical $N\overline{N}\to \pi \pi$ data. Using this approach we develop a prescription for resolving ambiguities of the correlated ππ exchange in the ρ channel that occur when different dispersion theoretical formulations of ρ exchange are used to construct $\pi N$ potentials.

Actinides with $N\sim 132$ present the best explored region of pear shape nuclei. Still almost no spectroscopic information is available for the heaviest elements, $Z=91\mathrm{}–98,$ which are predicted to be octupole instable. The lack of data for the latter nuclei results from the high fission probability encountered in the heavy-ion reactions used to populate them. In order to overcome this handicap, an $\alpha$-decay tagging technique was used to identify $\gamma$ rays in ${}^{223}\mathrm{Pa}$ produced through the ${}^{208}\mathrm{Pb}{(}^{19}\mathrm{F},4n)$ reaction. A new value of 4.9(4) ms for the half-life of ${}^{223}\mathrm{Pa}$ was obtained as a by-product.

Properties of transitional Lu and spherical Ta ground-state proton emitters are calculated with the relativistic Hartree-Bogoliubov model. The NL3 effective interaction is used in the mean-field Lagrangian, and pairing correlations are described by the pairing part of the finite range Gogny interaction D1S. Proton separation energies, ground-state quadrupole deformations, single-particle orbitals occupied by the odd valence proton, and the corresponding spectroscopic factors are compared with recent experimental data, and with results of the macroscopic-microscopic mass model.

The thermal mean-field (Hartree-Bose-Bogoliubov) approximation is applied to a simple bosonic model that is related to the phase transition from spherical to deformed nuclei. Similarities and differences with the time-dependent approach are discussed, in particular, the sensitivity of each method for the detection of the phase transition.

The neutron-to-proton density ratio at the nuclear periphery was determined for six targets from the yield of nuclei with mass ${(A}_t-1)$ generated by antiproton annihilation on targets with mass number $A_t.$ A new setup allowed us to measure this yield for nuclei with half-lives down to 6 s. The experiment confirmed the negative correlation between the peripheral neutron-to-proton density ratio and the neutron binding energy, which had been previously found. Results of Hartree-Fock-Bogoliubov and relativistic Hartree-Bogoliubov calculations show good agreement for a large number of nuclei. By comparing the measured values with those derived from Hartree-Fock-Bogoliubov calculations, the ratio R of the imaginary parts of the effective scattering lengths of antiprotons on bound neutrons and protons was deduced to be $\mathcal{R}=0.69\mathrm{}\left(4\right).$ For the first time yields of several excited states of some ${(A}_t-1)$ nuclei have been investigated.

Laser spectroscopy measurements have been carried out on very-neutron-deficient platinum isotopes with the COMPLIS experimental setup. Using the ${5d}^9{6s}^3{D}_3\to {5d}^9{6p}^3{P}_2$ optical transition, hyperfine spectra of ${}^{182,181,180,179,178}\mathrm{Pt}$ and ${}^{183}{\mathrm{Pt}}^m$ were recorded for the first time. The variation of the mean square charge radius between these nuclei, the magnetic moments of the odd isotopes, and the quadrupole moment of ${}^{183}{\mathrm{Pt}}^m$ were thus measured. A large deformation change between ${}^{183}{\mathrm{Pt}}^g$ and ${}^{183}{\mathrm{Pt}}^m,$ an odd-even staggering of the charge radius, and a deformation drop from $A=179\mathrm{}$ are clearly observed. Comparisons are made with microscopic theoretical predictions, in particular Hartree-Fock-Bogoliubov calculations using the Gogny force.

The Bertsch, nonparametric model of neutron matter is analyzed and strong indications are found that, in the infinite system limit, the ground state is a Fermi liquid with an effective mass, except for a set of measure zero.

The semiclassical distorted wave (SCDW) model of nucleon inelastic and charge exchange scattering at intermediate energies is modified to take accurate account of off-the-energy-shell matrix elements of the in-medium $N-N$ interaction and explicit account of the exchange of colliding two nucleons, making use of the G matrix parametrized in coordinate representation. The effects of the modification on the double differential inclusive cross sections are discussed for the cases of ${(p,p}^{\prime }x)$ and (p,nx) reactions on ${}^{90}\mathrm{Zr}$ at 160 MeV. The modification enables the SCDW model to calculate spin observables. The depolarizations in ${}^{58}\mathrm{Ni}{(p,p}^{\prime }x)$ at 80 MeV and ${}^{90}\mathrm{Zr}{(p,p}^{\prime }x)$ and ${}^{90}\mathrm{Zr}\mathrm{}(p,nx)\mathrm{}$ at 160 MeV by one- and two-step processes are calculated, and the result for ${}^{58}\mathrm{Ni}{(p,p}^{\prime }x)$ is compared with experimental data. The calculated spin flips in ${(p,p}^{\prime }x)$ and (p,nx) on ${}^{90}\mathrm{Zr}$ are analyzed in terms of the effects of in-medium modification of the $N-N$ interaction and the contributions of individual components of the effective interaction.

We study the coherent photoproduction of pseudoscalar mesons—particularly of neutral pions—placing special emphasis on the various sources that put into question earlier nonrelativistic-impulse-approximation calculations. These include final-state interactions, relativistic effects, off-shell ambiguities, and violations to the impulse approximation. We establish that while distortions play an essential role in the modification of the coherent cross section, the uncertainty in our results due to the various choices of optical-potential models is relatively small (at most 30%). By far the largest uncertainty emerges from the ambiguity in extending the many on-shell-equivalent representations of the elementary amplitude off the mass shell. Indeed, relativistic impulse-approximation calculations that include the same pionic distortions, the same nuclear-structure model, and two sets of elementary amplitudes that are identical on-shell, lead to variations in the magnitude of the coherent cross section by up to factors of 5. Finally, we address qualitatively the assumption of locality implicit in most impulse-approximation treatments, and suggest that the coherent reaction probes—in addition to the nuclear density—the polarization structure of the nucleus.