The first reports of $\psi$ and ${\psi }^{\prime }$ production from experiment NA50 at the CERN Super Proton Synchrotron are compared to calculations based on a hadronic model of charmonium suppression developed previously. Data on centrality dependence and total cross sections are in good accord with these predictions.

Mass shifts $\Delta m$ of particles in nuclear matter relative to their vacuum values are considered. A general formula relating $\Delta m\left(E\right)$ ( $E$ is the particle energy) to the real part of the forward particle-nucleon scattering amplitude $\mathrm{Re}f\left(E\right)$ is presented and its applicability domain is formulated. The $\rho$-meson mass shift in nuclear matter is calculated at $2\lesssim E_{\rho }\lesssim 7\mathrm{GeV}$ for transversally and longitudinally polarized $\rho$ mesons.

Differential cross sections and analyzing powers ( $A_y$) have been measured for the proton knockout reaction from $s_{1/2}$ orbits of three kinds of target nuclei at $E_p=392\mathrm{}\mathrm{MeV}$. The $A_y$ values are reduced from those of free proton-proton scattering and the reduction rate is found to depend on target. For the present setting, where the recoil momentum is almost zero, an averaged density seen through this reaction can be estimated and it reaches almost half of the saturation density in some cases. The reduction of $A_y$ shows a monotonically decreasing function of the averaged density, which strongly suggests the existence of a nuclear medium effect on the nucleon-nucleon interaction.

Angular correlations for the ${}^{12}\mathrm{C}({e,e}^{\prime }n{)}^{11}\mathrm{C}$ reaction in the giant resonance region have been measured for forward scattering at an effective momentum transfer of $0.35{\mathrm{fm}}^{-1\mathrm{}}$. The angular correlation for the ground-state transition indicates a strong forward-backward asymmetry at the peak of the giant dipole resonance $(\omega =22.5\mathrm{MeV})$, which is different from the nearly symmetric angular correlations observed for the ${}^{12}\mathrm{C}({e,e}^{\prime }{p}_0{)}^{11}\mathrm{B}$ reaction. Recent random-phase approximation predictions fail to reproduce the experimental angular correlations for both $\left({e,e}^{\prime }{n}_0\right)$ and $\left({e,e}^{\prime }{p}_0\right)$, predicting the opposite patterns to those observed.

Collective transverse flow of nuclear matter was measured as a function of the ratio of neutrons to protons ( $N/Z$) of the interacting system for the first time. The collisions of three isotopically pure beams of $A=58\mathrm{}\mathrm{nuclei}$ with two $A=58\mathrm{}\mathrm{targets}$ were studied at 55 MeV/nucleon. The results for the flow variables demonstrate the sensitivity of transport models to elementary aspects of the nucleon-nucleon collisions.

The energy at which collective transverse flow in the reaction plane disappears, the balance energy $E_{\mathrm{bal}}$, is found to depend on the isospin of the system using the reactions ${}^{58}\mathrm{Fe}{+}^{58}\mathrm{Fe}$ and ${}^{58}\mathrm{Ni}{+}^{58}\mathrm{Ni}$. The more neutron-rich system exhibits higher balance energies for all measured impact parameters, in agreement with the predictions of a transport model which incorporates an isospin dependent mean field and isospin dependent in-medium nucleon-nucleon cross sections.

The magnetic moments of ( $\mathrm{double}\mathrm{magic}+1\mathrm{}\mathrm{proton}$) nuclei having a “jack-knife” $j=l-s$ configuration form crucial tests for the theoretical treatment of mesonic exchange currents and core polarization effects in finite nuclei. The reported precision measurement and analysis of the magnetic moment of ${}^{133}\mathrm{Sb}$ ( ${}^{132}\mathrm{Sn}+\mathrm{one}{g}_{7/2}\mathrm{proton}$) $\mu =3.00\mathrm{}\left(1\right){\mu }_N$ provides the first such test in medium-heavy nuclei. In addition, new data on the N dependence of the ${7/2}^{+}{}^{123-133}\mathrm{Sb}$ ground state moments are presented. Analysis in terms of particle-core coupling indicates slightly negative collective g factors of heavy Sn core nuclei.

Coulomb bubbles, though stable against monopole displacement, are unstable at least with respect to quadrupole and octupole distortions. We show that there exists a temperature at which the pressure of the vapor filling the bubble stabilizes all the radial modes. In extremely thin bubbles, the crispation modes become unstable due to the surface-surface interaction.

Primary and secondary masses of heavy reaction products have been deduced from kinematics and energy–time-of-flight measurements, respectively, for the direct and reverse collisions of ${}^{100}\mathrm{Mo}$ with ${}^{120}\mathrm{Sn}$ at $14.1A$MeV. Direct experimental evidence of the correlation of energy sharing with net mass transfer and model-independent results on the evolution of the average excitation from equal-energy to equal-temperature partition are presented.

Four superdeformed bands have been observed in ${}^{87}\mathrm{Nb}$. Transition quadrupole moment measurements on three of the bands confirm superdeformed shapes. Two of the bands were observed to mutually interact, and cross transitions between them have been observed. This is the first time such behavior has been observed in mass 80 superdeformed bands. Once this interaction is accounted for, a second crossing appears in one of the bands. This crossing is interpreted as evidence for the occupation of the $i_{13/2}$ superintruder orbital, making ${}^{87}\mathrm{Nb}$ the lightest nucleus by far in which the shape-driving properties of this orbital can be studied.

Positron production in ${}^{238}\mathrm{U}{+}^{232}\mathrm{Th}$ and ${}^{238}\mathrm{U}{+}^{181}\mathrm{Ta}$ collisions near the Coulomb barrier has been studied. Earlier experiments reported narrow lines in the spectra of positrons, accumulated without the requirement of electrons detected in coincidence. No evidence of such structure is observed in the present data. The positron energy spectra are compared with estimates from dynamic atomic processes, and from internal pair conversion of electromagnetic transitions from the excited nuclei.

The longitudinal $\left({e,e}^{\prime }\right)$ response function of ${}^4\mathrm{He}$ is calculated precisely with full final state interaction. The explicit calculation of the four-body continuum states is avoided by the method of integral transforms. Precision tests of the response show the high level of accuracy. Nonrelativistic nuclear dynamics are used. The agreement with experimental data is very good over a large energy range for all considered momentum transfers ( $q=300\mathrm{}$, 400, $500\mathrm{MeV}/c$). Only at higher $q$ the theoretical response overestimates the experimental one beyond the quasielastic peak.

We show that pseudospin symmetry in nuclei could arise from nucleons moving in a relativistic mean field which has an attractive scalar and repulsive vector potential nearly equal in magnitude.

We present an attempt towards the many-body description of spontaneous fission based on the semiclassical Vlasov equation and the Feynman path integral method. We define suitable collective variables from the Vlasov solution and use the imaginary time technique for the dynamics below the Coulomb barrier. We demonstrate (1) the stability of the Vlasov solution, (2) the ability of this model to calculate the basic features of the whole spontaneous fission process, (3) the sensitivity of the dynamics below the barrier to the mean field potential, and (4) the important role of collective excitations and of particle emission during the fission process.

First results for the triton binding energy obtained from the relativistic spectator or Gross equation are reported. The Dirac structure of the nucleons is taken into account. Numerical results are presented for a family of realistic one-boson exchange models with off-shell scalar couplings. It is shown that these off-shell couplings improve both the fits to the two-body data and the predictions for the binding energy.

Complete fusion of light radioactive nuclei is predicted to be hindered at near-barrier energies. This feature is investigated in the case of the least bound stable nuclei. Evaporation residues resulting from the ${}^{6,7}\mathrm{Li}{+}^9\mathrm{Be}$ and ${}^{6,7}\mathrm{Li}{+}^{12}\mathrm{C}$ fusion reactions have been measured in order to study common features in reactions involving light weakly bound nuclei. The experimental excitation functions revealed that the fusion cross section is significantly smaller than the total reaction cross section and also smaller than the fusion cross section expected from the available systematics. A clear correlation between the fusion probability and nucleon (cluster) separation energy has been established. The results suggest that the breakup process has a strong influence on the hindrance of the fusion cross section.

We utilize precise weak interaction experiments on atomic muon capture and beta decay in the $A=3\mathrm{}$ nuclei and take into account the effects of nuclear “anomalous thresholds” to extract the pseudoscalar π${-}^3$He${-}^3$H coupling parameter, $G^{\mathrm{eff}}\left(m_{\pi }^2\right)=45.8\mathrm{}\pm 2.4$. This is an order of magnitude improvement in precision over that from the use of pion-nuclear scattering data and dispersion relations.

Quadrupole and hexadecapole moments of superdeformed bands in the $A\sim 150$ mass region have been analyzed in the cranking Skyrme-Hartree-Fock model. It is demonstrated that, independently of the intrinsic configuration and of the proton and neutron numbers, the charge moments calculated with respect to the doubly magic superdeformed core of ${}^{152}\mathrm{Dy}$ can be expressed very precisely in terms of independent contributions from the individual hole and particle orbitals.

${}^{48}\mathrm{Ca}$, the lightest experimentally accessible double beta decay candidate, is the only one simple enough to be treated exactly in the nuclear shell model. Thus the $\beta {\beta }_{2\nu }$ half-life measurement, reported here, provides a unique test of the nuclear physics involved in the $\beta \beta$ matrix element calculation. Enriched ${}^{48}\mathrm{Ca}$ sources of two different thicknesses have been exposed in a time projection chamber. We observe a half-life of ${\mathrm{T}}_{1/2}^{2\nu }=\left({4.3}_{-1.1\mathrm{}}^{+2.4\mathrm{}}\right[\mathrm{stat}]\pm 1.4[\mathrm{syst}\left]\right)\times {10}^{19}$ yr, consistent with shell model calculations.