The role of meson exchange currents (MEC) in electron- and photon-induced one-nucleon emission processes is studied in a nonrelativistic model including correlations and final state interactions. The nuclear current is the sum of a one-body and of a two-body part. The two-body current includes pion seagull, pion-in-flight, and the isobar current contributions. Numerical results are presented for the exclusive ${}^{16}\mathrm{O}{(e,e}^{\prime }{p)}^{15}\mathrm{N}$ and ${}^{16}\mathrm{O}(\gamma {,p)}^{15}\mathrm{N}$ reactions. MEC effects are in general rather small in ${(e,e}^{\prime }p),$ while in $(\gamma ,p)$ they are always large and important to obtain a consistent description of ${(e,e}^{\prime }p)$ and $(\gamma ,p)$ data, with the same spectroscopic factors. The calculated $(\gamma ,p)$ cross sections are sensitive to short-range correlations at high values of the recoil momentum, where MEC effects are larger and overwhelm the contribution of correlations.

The ${}^6\mathrm{He}$ $+$ ${}^4\mathrm{He}$ elastic scattering cross section was measured at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=11.6\mathrm{}\mathrm{MeV}$ using a ${}^6\mathrm{He}$ radioactive beam and a ${}^4\mathrm{He}$-implanted Al foil as target. The use of the thin implanted target allowed to enlarge the angular range in which the data were collected, with respect to a previous measurement at the same center-of-mass energy. The new and previous data are compared with several calculations. The inclusion of a description for the $2n$-transfer process, either with a parity-dependent term, or with a distorted-wave Born approximation transfer amplitude, is crucial to reproduce the increase of the cross section at large angles, thus assessing the contribution of the $2n$-transfer process to the reaction. At the present energy, the complicated nature of the transfer process and the possible role played by the coupling to other channels, in particular, the breakup, require sophisticated reaction models in order to extract the relevant information on the peculiar ${}^6\mathrm{He}$ nucleus. The quality of the data is such that the differences between ${}^6\mathrm{He}$ and the similar ${}^6\mathrm{Li}$ system should be identified by such calculations.

Results on the study of localized fluctuations in the multiplicity of charged particles and photons produced in $158A\mathrm{GeV}/c$ Pb+Pb collisions are presented for varying centralities. The charged versus neutral particle multiplicity correlations in common phase space regions of varying azimuthal sizes are analyzed by two different methods. Various types of mixed events are constructed to probe fluctuations arising from different sources. The measured results are compared to those from simulations and from mixed events. The comparison indicates the presence of nonstatistical fluctuations in both the charged particle and photon multiplicities in limited azimuthal regions. However, no correlated charged-neutral fluctuations, a possible signature of formation of disoriented chiral condensates, are observed. An upper limit on the production of disoriented chiral condensates is set.

We calculate $K^{-}$-nucleus elastic differential, reaction, and total cross sections for different nuclei ${(}^{12}\mathrm{C},$ ${}^{40}\mathrm{Ca},$ and ${}^{208}\mathrm{Pb})$ at several laboratory antikaon momenta, ranging from 127 MeV to 800 MeV. We use different antikaon-nucleus optical potentials, some of them fitted to kaonic atom data, and study the sensitivity of the cross sections to the considered antikaon-nucleus dynamics.

High angular momentum states in ${}^{86}\mathrm{Zr}$ were populated through the ${}^{58}\mathrm{Ni}{(}^{32}\mathrm{S},4p)$ reaction at 135 MeV using the 88-In. Cyclotron at Lawrence Berkeley National Laboratory. Recoiling ${}^{86}\mathrm{Zr}$ nuclei were stopped in a thick Ta backing. Prompt multi-$\gamma$ coincidences with evaporated charged particles were detected using the full array of GAMMASPHERE and the MICROBALL. Mean lifetimes of 36 levels in ${}^{86}\mathrm{Zr}$ were measured using the Doppler-shift attenuation method. Transition quadrupole moments $Q_t$ were found in the range of about $0.3–1.5e\mathrm{b}$ in the positive-parity bands. The negative-parity bands show $Q_t$ values from about 0.25 to $1.2e\mathrm{b}.$ In the yrast positive-parity band, a sharp drop in collectivity approaching the ${30}^{+}$ state supports the interpretation of band termination in this configuration. Decreasing $Q_t$ values approaching the ${24}^{+}$ and ${27}^{-}$ states also provide an indication of terminating structures.

We present new experimental data on directed flow in collisions of $\mathrm{Au}+\mathrm{Au},$ $\mathrm{Xe}+\mathrm{CsI},$ and $\mathrm{Ni}+\mathrm{Ni}$ at incident energies from $90A$ to $400A\mathrm{MeV}.$ We study the centrality and system dependence of integral and differential directed flow for particles selected according to charge. All the features of the experimental data are compared with isospin quantum molecular dynamics (IQMD) model calculations in an attempt to extract information about the nuclear matter equation of state (EoS). We show that the combination of rapidity and transverse momentum analysis of directed flow allows to disentangle various parametrizations in the model. At $400A\mathrm{MeV},$ a soft EoS with momentum dependent interactions is best suited to explain the experimental data in $\mathrm{Au}+\mathrm{Au}$ and $\mathrm{Xe}+\mathrm{CsI},$ but in the case of $\mathrm{Ni}+\mathrm{Ni}$ the model underpredicts flow for any EoS. At $90A\mathrm{MeV}$ incident beam energy, none of the IQMD parametrizations studied here are able to consistently explain the experimental data.

Properties of low-spin states in ${}^{114}\mathrm{Cd}$ have been studied with the ${(n,n}^{\prime }\gamma )$ reaction. $\gamma$-ray angular distributions and excitation functions have been used to characterize the decays of the excited levels, and level lifetimes have been obtained with the Doppler-shift attenuation method. The one-phonon, mixed-symmetry strength is found to be concentrated in the $2_6^{+}$ state, which exhibits a strong $M1\mathrm{}$ transition to the first-excited $2^{+}$ state and a weak $E2\mathrm{}$ transition to the ground state. The data agree well with expectations of the neutron-proton interacting boson model.

We have calculated the one-body Fermi and Gamow-Teller charge-current and vector and axial-vector neutral-current nuclear matrix elements in nucleon matter at densities of 0.08, 0.16, and $0.24{\mathrm{fm}}^{-3}$ and proton fractions ranging from 0.2 to 0.5. The correlated states for nucleon matter are obtained by operating on Fermi-gas states by a symmetrized product of pair correlation operators determined from variational calculations with the Argonne-v18 and Urbana-IX two- and three-nucleon interactions. The squares of the charge- current matrix elements are found to be quenched by 20–25 % by the short-range correlations in nucleon matter. Most of the quenching is due to spin-isospin correlations induced by the pion exchange interactions which change the isospins and spins of the nucleons. A large part of it can be related to the probability for a spin-up proton quasiparticle to be a bare spin-up/down proton/neutron. Within the interval considered, the charge-current matrix elements do not have significant dependence on the matter density, proton fraction, and magnitudes of nucleon momenta; however, they do depend on momentum transfer. The neutral-current matrix elements have a significant dependence on the proton fraction. We also calculate the matrix elements of the nuclear Hamiltonian in the same correlated basis. These provide relatively mild effective interactions that give the variational energies in the Hartree-Fock approximation. The calculated two-nucleon effective interaction describes the spin-isospin susceptibilities of nuclear and neutron matter fairly accurately. However terms greater than or equal to three-body terms are necessary to reproduce the compressibility. Realistic calculations of weak interaction rates in nucleon matter can presumably be carried out using the effective operators and interactions studied here. All presented results use the simple two-body cluster approximation to calculate the correlated basis matrix elements. This allows for a clear discussion of the physical effects in the effective operators and interactions.

A facility for detection of scattered neutrons in the energy interval 50–130 MeV, scattered nucleon detection assembly, has recently been installed at the 20–180 MeV neutron beam line of The Svedberg Laboratory, Uppsala. First results on elastic neutron scattering from ${}^{12}\mathrm{C}$ and ${}^{208}\mathrm{Pb}$ at 96 MeV incident neutron energy are presented. This experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. The results are compared with modern optical model predictions.

We use a fully self-consistent Hartree-Fock (HF) based continuum random phase approximation (CRPA) to calculate strength functions $S\left(E\right)\mathrm{}$ and transition densities ${\rho }_t\mathrm{}\left(r\right)\mathrm{}$ for isoscalar giant resonances with multipolarities $L=0,$ 1, and 2 in ${}^{80}\mathrm{Zr}$ nucleus. In particular, we consider the effects of spurious state mixing (SSM) in the isoscalar giant dipole resonance and extend the projection method to determine the mixing amplitude of the spurious state so that properly normalized $S\left(E\right)\mathrm{}$ and ${\rho }_t\mathrm{}\left(r\right),$ having no contribution due to SSM, can be obtained. For the calculation to be highly accurate, we use a very fine radial mesh (0.04 fm) and zero smearing width in HF-CRPA calculations. We use our most accurate results as a basis to (i) establish the credibility of the projection method, employed to eliminate the SSM, and (ii) to assess the consequences of the common violations of self-consistency, often encountered in actual implementation of HF based CRPA and discretized RPA (DRPA) published in the literature, on the values of $S\left(E\right)\mathrm{}$ and ${\rho }_t\mathrm{}\left(r\right).$ This is achieved by varying the radial mesh size, the particle-hole interaction, the smearing parameter, and the particle-hole energy cutoff used in the HF-RPA calculations.

The energy of a compound nuclear system rotating in the quasimolecular shape path has been determined within a generalized liquid drop model and a two-center shell model. The normally deformed minimum disappears at the highest spins while second and third deformed minima able to lodge super and highly deformed states appear progressively with increasing angular momenta. The ${}^{16}\mathrm{O}{+}^{28}\mathrm{Si}$ and ${}^{28}\mathrm{Si}{+}^{28}\mathrm{Si}$ reactions leading respectively to the compound systems ${}^{44}\mathrm{Ti}$ and ${}^{56}\mathrm{Ni}$ and the rotating ${}^{126}\mathrm{Ba}$ nucleus formed in the ${}^{64}\mathrm{Ni}{(}^{64}\mathrm{Ni}{,2n)}^{126}\mathrm{Ba}$ reaction are particularly investigated.

Two experiments have been performed using the ${}^{58}\mathrm{Ni}{(}^{32}\mathrm{S},3p)$ reaction at 135 MeV with Gammasphere and the Microball to study the high-spin structure of the transitional nucleus ${}^{87}\mathrm{Nb}.$ The first experiment using a thin target provided a considerable extension and refinement of the level scheme, as well as firm spin assignments from directional correlation of oriented nuclei. Sub-picosecond lifetimes were measured in the second backed-target experiment using the Doppler-shift attenuation method. The lifetimes imply a rather modest average deformation of ${\beta }_2\sim 0.1,$ but with considerable variation from state to state. Strong alternations were observed in the $B\left(M1\mathrm{}\right)\mathrm{}$ strengths of transitions between some pairs of bands. The experimental results were compared with calculations performed within the cranked Nilsson-Strutinsky approach. The calculations generally reproduce the irregularities in the structure of the yrast lines and plunging transition quadrupole moments $Q_t$ within the bands explaining them as reflections of configuration changes and an approach of band termination, respectively.

Charge-density distributions and the associated nuclear radii are calculated with the Hartree-Fock method for comparison with available data from electron scattering. Two forms of Skyrme interactions are used for the calculations. As a further refinement the single-particle occupancies are constrained to values obtained from shell-model calculations. A significant improvement in the agreement is obtained if shell-model occupancies are used.

$\gamma$ Rays in the $\pi {\nu }^{-1}$ nucleus ${}^{208}\mathrm{Bi}$ have been studied at the Gammasphere using deep-inelastic reactions induced by a $305-\mathrm{MeV}{\hspace{0.5em}}^{48}\mathrm{Ca}$ beam on a thick ${}^{208}\mathrm{Pb}$ target. Previously unknown yrast $\gamma$-ray cascades above the ${10}^{-}$ millisecond isomer in ${}^{208}\mathrm{Bi}$ were identified in cross coincidence with known $\gamma$ rays from complementary potassium products. Yrast and near-yrast levels up to 5.6 MeV in ${}^{208}\mathrm{Bi}$ have been located, and they are interpreted in light of earlier charged particle spectroscopy results, and with the help of shell model calculations.

For transport model simulations of collisions between two nuclei which have $N/Z$ significantly different from unity one needs a one-body potential which is both isospin and momentum dependent. This work provides sets of such potentials.

The differential cross section for the reaction $p{d}^3\mathrm{He}\eta$ in the energy region 930–1100 MeV is investigated in a two-step model. The model assumes a $\pi$ meson to be produced in a first $N\overrightarrow{N}\pi d$ collision and the $\eta$ meson in a second $\pi \overrightarrow{N}\eta N$ collision. Part of the angular dependence observed is ascribed to the $\pi \overrightarrow{N}\eta N$ amplitude, through its dependence on the $P_{11}$ and $D_{13}$ resonances, but the main structure comes from the ${}^3\mathrm{He}$ form factor. Fermi motion is taken into account, but does not seem to significantly change the results. The two-step model by itself is not completely successful in explaining the $p{d}^3\mathrm{He}\eta$ differential cross section, but basic features are reproduced.

The $Q_{\mathrm{EC}}$ value of ${}^{80}\mathrm{Y}$ has been measured by β-γ coincidence spectroscopy to be ⩾8929(83) keV. Combining this result with the adopted mass excess of the daughter ${}^{80}\mathrm{Sr}$ gives a mass excess for ${}^{80}\mathrm{Y}$ of ⩾-61 376(83) keV. Results are compared with other measurements, with Audi-Wapstra systematics, and with predictions of mass formulas. Implications of this measurement are considered for the rp process.

A variable combination of realistic and random two-body interactions allows the study of collective properties [such as the energy spectra and $B\left(E2\mathrm{}\right)\mathrm{}$ transition strengths] in ${}^{44}\mathrm{Ti},$ ${}^{48}\mathrm{Cr},$ and ${}^{24}\mathrm{Mg}.$ It is found that the average energies of the yrast band states maintain the ordering for any degree of randomness, but the $B\left(E2\mathrm{}\right)\mathrm{}$ values lose their quadrupole collectivity when randomness dominates the Hamiltonian. The high probability of the yrast band to be ordered in the presence of pure random forces exhibits the strong correlations between the different members of the band.

The relativistic quasiparticle random phase approximation (RQRPA) is formulated in the canonical single-nucleon basis of the relativistic Hartree-Bogoliubov (RHB) model. For the interaction in the particle-hole channel effective Lagrangians with nonlinear meson self-interactions are used, and pairing correlations are described by the pairing part of the finite-range Gogny interaction. The RQRPA configuration space includes the Dirac sea of negative-energy states. Both in the particle-hole and particle-particle channels, the same interactions are used in the RHB calculation of the ground state and in the matrix equations of the RQRPA. The RHB+RQRPA approach is tested in the example of multipole excitations of neutron-rich oxygen isotopes. The RQRPA is applied in the analysis of the evolution of the low-lying isovector dipole strength in Sn isotopes and $N=82\mathrm{}$ isotones.

Hartree-Fock calculations with the SKX Skyrme interaction are carried out to obtain α-decay Q values for deformed nuclei above ${}^{208}\mathrm{Pb}$ assuming axial symmetry. The results for even-even nuclei are compared with the experiment and with the previous calculations. Predictions are made for α-decay Q values and half-lives of even-even superheavy nuclei. The results are also compared for the recently discovered odd-even chain starting at $Z=112\mathrm{}$ and $N=165.\mathrm{}$