High energy γ rays from the decay of the giant dipole resonance built on highly excited states in ${}_{}{}^{164}{}_{}{}^{}\mathrm{Yb}$ at ${\mathit{E}}_{\mathrm{ex}}$=49 MeV formed in two different reactions have been measured. While standard statistical model calculations can describe the γ-ray spectrum from the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{148}{}_{}{}^{}\mathrm{Sm}$ reaction they fail to reproduce the γ-ray spectra from the more symmetric reaction ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$ + ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$. Simple model calculations which include particle evaporation and γ-ray decay during the formation process suggest that the observed differences may be related to a long fusion time in the more symmetric reaction.

For simple models of the nuclear charge operator, measurements of the Coulomb sum and the charge form factor of a nucleus directly determine the proton-proton correlations. We examine experimental results obtained for few-body nuclei at Bates and Saclay using models of the charge operator that include both one- and two-body terms. Previous analyses using one-body terms only have failed to reproduce the experimental results. However, we find that the same operators which have been used to successfully describe the charge form factors also produce substantial agreement with measurements of the Coulomb sum.

We have measured two-fragment reduced-velocity correlation functions of the intermediate mass fragments (IMF: 3≤Z≤7) produced in multifragment final states for the Kr+Nb system (E/A=35, 45, 55, 65, and 75 MeV). From the measured correlation functions we extract mean IMF emission lifetimes (τ) which are observed to decrease from τ≊400 fm/c at E/A=35 MeV to τ≊125 fm/c at E/A=55 MeV. For beam energies in excess of E/A=55 MeV, no further decrease in τ is observed, indicating a possible saturation of the mean emission lifetime for IMF produced in multifragment exit channels.

The momentum dependence of the two-proton correlation function is studied for central and peripheral ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$${+}^{45}$Sc collisions at E/A=80 MeV. Calculations with the Boltzmann-Uehling-Uhlenbeck transport theory reproduce well the measured momentum dependence of the correlation functions for central collisions, but underpredict the momentum dependence for peripheral collisions.

We determine the entropy-per-baryon content of the central reaction region in terms of the charged particle multiplicity. We study the consistency of our findings with recent data on strange antibaryon production at 200A GeV in S-A collisons (A∼200) assuming formation of a central fireball. Hadron gas models which do not invoke strong medium modifications of hadron masses do not provide enough entropy and are inconsistent with the combined experimental results. In contrast the quark-gluon plasma hypothesis explains them naturally.

Velocity distributions and fragment-fragment correlation functions have been measured as a function of charged particle multiplicity for ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$${+}^{\mathrm{nat}}$Cu collisions at E/A=50 MeV. With increasing multiplicity, the velocity distributions evolve from a pattern exhibiting targetlike and projectilelike sources to an anisotropic distribution centered near the projectile-target center-of-mass velocity. Emission times extracted from the correlation functions are consistent with the decay of a projectilelike source in low multiplicity collisions, but the time scale for fragment emission in the high multiplicity collisions is too short for a separation of sources to occur.

Fission dynamics of hot nuclei have been investigated using the two-dimensional Langevin equation. Including particle evaporation in the continuous limit, prescission multiplicities of neutrons, protons, and α particles have been calculated. Both the calculated number of prescission neutrons and the average total kinetic energy of fission fragments are consistent with experimental values when one-body dissipation is assumed. Unusually strong hydrodynamical two-body viscosity also reproduces the experimental neutron multiplicity, but it significantly underestimates the average kinetic energy.

It is argued that color transparency in quasielastic scattering of electrons and hadrons on nuclei is possible only due to Fermi motion. We found a strong dependence of nuclear transparency on Bjorken x in (e,e’p); it is close to the Glauber model expectations at x>1, but increases and even exceeds one at x<1. It is argued that color transparency is accompanied by large longitudinal momentum transfer to nuclear matter during the passage of the small size wave packet.

We have deduced compound nuclear isospin mixing in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}_{}^{\mathrm{*}}{}_{}{}^{}$ and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}_{}^{\mathrm{*}}{}_{}{}^{}$ at excitation energies between 33 and 65 MeV. The γ-ray yield from the decay of giant dipole resonances built on excited states is found to be suppressed, implying that isospin mixing is small. By comparison with data from the literature at lower excitation energy, we conclude that isospin is a better symmetry in these compound nuclei at high excitation energy.

We have measured the spin correlation coefficient (${\mathit{C}}_{\mathit{N}\mathit{N}}$) and the neutron and proton analyzing powers (${\mathit{A}}_{\mathit{n}}$ and ${\mathit{A}}_{\mathit{p}}$) for the n→p→→dγ reaction at a neutron beam energy of 183 MeV. Calculations of the spin correlation are particularly sensitive to the treatment of mesonic and isobaric currents. Predictions that include both explicit photon couplings to exchanged mesons and intermediate isobar states, and relativistic correction terms in the Hamiltonian, agree well with our data, thus demonstrating the quantitative accuracy of present treatments of meson-exchange currents at moderate momentum transfer (q∼1-2 ${\mathrm{fm}}^{\mathrm{-}1}$).

The energy dependence of the giant dipole resonance built on the isobaric analog state was measured in pion-induced double charge exchange on ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ at incident pion energies of 140–295 MeV. The cross section increases with energy. The excitation function has a typical non-spin-flip signature, expected from simple considerations and verified by sequential model calculations. Three narrower previously reported low-lying states in ${}_{}{}^{13}{}_{}{}^{}\mathrm{O}$ (${\mathit{E}}_{\mathit{x}}$=3.1, 4.5, and 6.1 MeV) exhibit a spin-flip signature and may correspond to the giant Gamow-Teller strength built on the isobaric analog state.

We present a systematic study of transverse energy (${\mathit{E}}_{\mathit{T}}$) production in collisions of 11.4A GeV/c Au and 14.6A GeV/c Si ions with targets of Al, Au, and Pb. Comparison of data for Au+Au and Si+Al indicates that, for the heavier system, there is an increase in the amount of stopping which is accompanied by a decrease in the width of the ${\mathit{dE}}_{\mathit{T}}$/dη distribution. The ratio of the maximum ${\mathit{E}}_{\mathit{T}}$ observed for the two systems is significantly greater than the ratio of the total energy available in the center of mass frame.

Bose-Einstein correlations between charged pion and ${\mathit{K}}^{+}$ pairs are calculated using the space-time and four-momentum distributions from relativistic quantum molecular dynamics for 200 GeV/nucleon ${}_{}{}^{32}{}_{}{}^{}$S+Pb and compared to pion correlation measurements from two CERN experiments. Good agreement is found. The predicted apparent radii from the ${\mathit{K}}^{+}$ correlation functions are smaller than the corresponding pion radii.

We have examined the double-beta decay mode accompanied by Majoron emission. After 223 days of measurement corresponding to about 615 kg d or 19.3 mol yr of exposure we find a lower half-life limit for this decay channel of ${\mathit{T}}_{1/2}^{0\nu \mathrm{\chi }}$>1.66(1.99)×${10}^{22}$ yr [90% (68%) C.L.] yielding a new limit for the Majoron-neutrino coupling of 〈${\mathit{g}}_{\nu \mathrm{\chi }}$〉<1.8×${10}^{\mathrm{-}4}$ (90% C.L.).

I point out that β-delayed proton spectroscopy is a powerful probe of possible scalar contributions to nuclear β decay, and use Schardt and Riisager’s data on the shape of the beta-delayed proton peaks from the superallowed decays of ${}_{}{}^{32}{}_{}{}^{}\mathrm{Ar}$ and ${}_{}{}^{33}{}_{}{}^{}\mathrm{Ar}$ to set improved upper limits on such couplings. Implications of these limits for leptoquark masses are mentioned.

We study dilepton production from a quark-gluon plasma of given energy density at finite quark chemical potential μ and find that the dilepton production rate is a strongly decreasing function of μ. Therefore, the signal to background ratio of dileptons from a plasma created in a heavy-ion collision may decrease significantly.

The total cross section for pion production in the reaction pd→pd${\mathrm{\pi }}^0$ has been measured for bombarding energies from ${\mathit{T}}_{\mathit{p}}$=208.4 MeV to 294.6 MeV. This corresponds to maximum pion momenta η=${\mathit{p}}_{\mathrm{\pi },\mathrm{c}.\mathrm{m}.\mathrm{}}$/${\mathit{m}}_{\mathrm{\pi }}$c between 0.099 and 0.96. The experiment was performed using an electron-cooled proton beam and an internal deuterium gas jet target. The resulting ${\mathrm{\sigma }}_{\mathrm{tot}}$ changes by almost four orders of magnitude over the covered energy range. The results are compared to a model which assumes quasi-free production via the pn→d${\mathrm{\pi }}^0$ elementary process.

The ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(e,e’p${)}^3$H reaction has been measured at a missing momentum of 265 MeV/c. Data were taken to determine the ${\mathit{R}}_{\mathit{L}}$, ${\mathit{R}}_{\mathit{T}}$, and ${\mathit{R}}_{\mathit{L}\mathit{T}}$ response functions. The extracted response functions show substantial differences from a microscopic calculation that includes the plane wave impulse approximation, final state interactions, and meson exchange currents, but agree much better with a calculation that includes orthogonality corrections, short range correlations, and final state interactions.

We have measured the first complete angular correlations of α-particle emission from the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ isoscalar giant quadrupole resonance (${\mathrm{GQ}}_0$R) following excitation by inelastic electron scattering, for momentum transfers from 0.24 to 0.61 ${\mathrm{fm}}^{\mathrm{-}1}$. Analysis of these uniquely determines the ${\mathrm{GQ}}_0$R strength distribution for the ${\mathrm{\alpha }}_0$ channel and sets limits on that for ${\mathrm{\alpha }}_1$.

The high-spin properties of the density dependent Gogny force are analyzed for the first time. The self-consistent cranking Hartree-Fock-Bogoliubov equations have been solved to analyze the rotational nucleus ${}_{}{}^{164}{}_{}{}^{}\mathrm{Er}$. We study pairing properties, moments of inertia, E2 transitions, and gyromagnetic factors, among others, as a function of the angular momentum. The agreement with the available experimental results is very satisfactory.