The flow of kaons, i.e., the average kaon transverse momentum as a function of rapidity, and the associated flow parameter in heavy-ion collisions at energies of the heavy-ion synchrotron SIS at GSI (around 1 GeV) is investigated in the relativistic transport model. It is found that the pattern of kaon flow at the final stage is sensitive to the kaon potential used in the model and is thus a useful probe of the kaon potential in a nuclear medium.

Distributions of the parallel momentum of ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ fragments from the breakup of $63A$ MeV ${}_{}{}^{11}{}_{}{}^{}\mathrm{Be}$ have been measured for ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$, ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$, and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ targets. The distributions have similar narrow widths with a mean value of 43.6 ± 1.1 MeV/c FWHM, and agree with a theoretical momentum distribution for the valence neutron in ${}_{}{}^{11}{}_{}{}^{}\mathrm{Be}$. The breakup mechanisms do not appear to distort the parallel momentum distribution of the ${}_{}{}^{10}{}_{}{}^{}\mathrm{Be}$ core. These findings support the existence of a one-neutron halo in ${}_{}{}^{11}{}_{}{}^{}\mathrm{Be}$ and the use of the parallel momenta of the heavy breakup products as a reliable probe of halo neutron momenta.

The nuclear density overlap, which occurs during refractive heavy-ion scattering, opens an alternative approach to study the equation of state (EOS) for cold nuclear matter. For this purpose elastic ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ scattering at incident enegies of 145, 250, 350, and 480 MeV has been measured very accurately, up to large angles. A systematic folding analysis of these data has been performed using an effective density dependent interaction based on the $G$-matrix elements of the Paris nucleon-nucleon potential. We find, with the observed refractive scattering patterns, that a soft EOS (with the nuclear incompressibility $K$ around 200 MeV) is the most realistic one.

Fragment distributions have been measured for Au + Au collisions at $\frac{E}{A}=100\mathrm{} \mathrm{and} 1000$ MeV. A high detection efficiency for fragments was obtained by combining the ALADIN spectrometer and the MSU-Miniball/WU-Miniwall array. At both energies the maximum multiplicity of intermediate mass fragments (IMF) normalized to the size of the decaying system is about one IMF per 30 nucleons but the element distributions show significant differences. Within a coalescence picture the suppression of heavy fragments in central collisions at $\frac{E}{A}=100\mathrm{}$ MeV may be related to a reduction of the density in momentum space which is caused by the collective expansion.

We derive a $T$-violating $P$-conserving optical potential for neutron-nucleus scattering, starting from a uniquely determined two-body $\rho$-exchange interaction with the same symmetry. We then obtain limits on the $T$-violating $\rho$-nucleon coupling ${\overline{g}}_{\rho }$ from neutron-transmission experiments in ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$. The limits may soon compete with those from measurements of atomic electric-dipole moments.

A novel method is presented for introducing fluctuations in one-body dynamics. It consists of employing a Brownian force in the kinetic equations. For nuclear matter within the spinodal zone, the magnitude of the Brownian force can be determined by demanding correspondence with the growth of the most unstable mode, as given by Boltzmann-Langevin simulations. The method is illustrated and tested for idealized two-dimensional matter and promises to provide a practical means for addressing catastrophic nuclear processes.

Complete sets of polarization transfer coefficients have been measured for quasifree ($\overrightarrow{p},\overrightarrow{n}$) scattering from ${}_{}{}^2{}_{}{}^{}\mathrm{H}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ at 494 MeV and scattering angles of 12.5°, 18°, and 27° ($q=1.2, 1.7, 2.5$ ${\mathrm{fm}}^{-1\mathrm{}}$). These measurements yield separated transverse ($\sigma \times q$) and longitudinal ($\sigma ·q$) isovector spin responses. Comparison of the separated responses to calculations and to electron-scattering responses reveals a strong enhancement in the spin transverse channel. This excess transverse strength masks the effect of pionic correlations in the response ratio.

Lifetimes of superdeformed (SD) states in ${}_{}{}^{194}{}_{}{}^{}\mathrm{Pb}$ were measured with the recoil distance Doppler shift method. The transition quadrupole moments were found to be constant in the whole SD band down to the lowest observed transition. The lifetime of the spin $10\hslash$ SD state is reduced as compared to the rotational value due to the $\gamma$ decay out of the band. This decay can be described by a very small admixture of normal deformed states to the spin $10\hslash$ SD state. The obtained lifetimes provide strong experimental evidence for the existence of the SD configuration down to very low spin states.

Theories that predict kaon condensation in neutron star matter at high densities also make predictions of the form of the density dependent dispersion relation for a $K$ meson moving through nuclear matter. The dispersion relation for the $K^{-}$ in matter at the density of ordinary nuclei then has the property that for sufficiently large momentum $k$ the energy-momentum becomes spacelike, $\omega <k$. The reactions ${\overline{\nu }}_e\to K^{-}+e^{+}$ and ${\overline{\nu }}_{\mu }\to K^{-}+{\mu }^{+}$ become kinematically allowed inside the nucleus, and can be used to gain information on the dispersion relation and on the underlying theory.

Energy spectra for intermediate mass fragments produced in central Au + Au collisions at $\frac{E}{A}=100\mathrm{}$ MeV indicate a collective expansion at breakup. For the first time, values for this collective expansion energy per nucleon are extracted independently for each charge. Typically, these values are one-third to one-half of the incident kinetic energy per nucleon in the c.m. system, but they decrease with $Z_f$, suggesting that all fragments do not participate equally in the collective expansion.

A new method to study the nuclear periphery using antiproton annihilation was applied to nine isotopes with mass numbers between 58 and 238. The method makes use of the detection of the radioactive annihilation products one unit lower in mass number than the target. A clear neutron halo effect, strongly correlated with the neutron binding energy, was observed in some nuclei. The experimental results are in qualitative agreement with calculations of proton and neutron densities at the nuclear periphery based on either a simple asymptotic density model or a more complex Hartree-Fock approach.

It is shown that nuclear three-body potentials involve spin operators of a type not allowed for ordinary two-body $\mathrm{NN}$ interactions. The effect of these operators on the wave function for proton-induced deuteron breakup is discussed, and a class of polarization observables is identified that may have enhanced sensitivity to the three-body forces.

The ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}(p,\gamma ){}_{}{}^{20}{}_{}{}^{}\mathrm{Na}$ reaction may influence considerably the reaction flow between the CNO and NeNa mass regions in high temperature hydrogen burning conditions. The 447 keV resonance has been studied by exploiting radioactive ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ beams with novel detection techniques to measure ${\beta }^{+}$ -delayed $\alpha$ radioactivity of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Na}$ nuclei produced in reactions with polyethylene targets. A 90% C.L. upper limit of 18 meV for the resonance strength has been determined and implications for the spin assignment of the 2.646 MeV state in ${}_{}{}^{20}{}_{}{}^{}\mathrm{Na}$ and the stellar reaction rate are discussed.

Intermediate mass fragment (IMF: $3\le Z\le 20$ emission from necklike structures joining projectilelike and targetlike residues has been observed for peripheral ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$ + ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Cu}$ collisions at $\frac{E}{A}=50\mathrm{}$ MeV. These fragments are emitted primarily at velocities between those of the projectilelike and targetlike residues. Relative to the charge distribution of fragments evaporated from projectilelike residues, the distribution for "neck" emission shows an enhanced emission for fragments with $4\le Z_{\mathrm{IMF}}\le 12$. This feature is consistent with expectations for the fragmentation of a noncompact cylindrical configuration.

The distribution of quadrupole phonon strength to low-lying states in nuclei is examined. It is found that the $2_1^{+}$ and $4_1^{+}$ states of all nuclei from $Z=30\mathrm{} \mathrm{to} 100$ display almost perfect quadrupole phonon character even though they encompass widely ranging structures. The interacting boson approximation reproduces both the very small deviations from phonon purity and the distribution of those deviations as a function of mean field structure in a natural fashion. Simple physical mechanisms explain these results.

The study of backward-forward and forward-forward correlations in collisions of two nuclei at high energies allow us to distinguish between the fusion of strings produced in the collision into new strings of higher color and the possibility of the fusion of produced hadrons into clusters. The results for $\mathrm{AB}$ collisions at the CERN Super Proton Synchrotron (SPS) and the Brookhaven Relativistic Heavy Ion Collider (RHIC) are discussed.

We investigate conditions for the occurrence of Efimov states in the recently discovered halo nuclei. These states could appear in systems where one neutron is added to a pronounced one-neutron halo nucleus. Detailed calculations of the properties of the states are presented and promising candidates are discussed.

Intermittency properties of the multiplicity fluctuations in high energy heavy ion collisions have been studied on the basis of the Landau mean field approach. A universal scaling exponent for the hadron phase is found which does not depend on whether the transition is of first or second order. It is further shown that the multiplicity distributions at different rapidity intervals carry more discriminating information about the nature of the phase transition.

The multiplicities of energetic $\gamma$ rays have been measured in coincidence with both evaporation residues and fission fragments in the reactions of ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ on ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ at projectile energies of 90, 100, 110, 120, 130, and 140 MeV. The experimental data have been compared with results of statistical calculations, which take into account dynamical fission hindrance. The damping of the fission partial width has been determined as a function of excitation energy in ${}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}$.

The cross section for Coulomb dissociation of ${}_{}{}^8{}_{}{}^{}\mathrm{B}$—the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}\left({}_{}{}^8{}_{}{}^{}\mathrm{B}{}_{}{}^7{}_{}{}^{}\mathrm{Be}p\right){}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ reaction—was measured using a ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ radioactive beam of 46.5 MeV/nucleon energy, and the cross section for the ${}_{}{}^7{}_{}{}^{}\mathrm{Be}(p,\gamma ){}_{}{}^8{}_{}{}^{}\mathrm{B}$ capture reaction was deduced at low energies; $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=0.6-1.7\mathrm{}$ MeV. The extracted astrophysical $S_{17}$ factors were found to be consistent with the values measured by Vaughn et al. and Filippone et al. This result encourages further experimental studies extended to lower relative energies for a new determination of the $S_{17}$ value relevant to the ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ solar neutrino flux.