An exclusive coincidence experiment using the $\left({p,n}_{\mathrm{IAS}}\tilde{p}\right)$ reaction on ${}^{140}\mathrm{Ce}$, ${}^{172,174,176}\mathrm{Yb}$, and ${}^{208}\mathrm{Pb}$ was carried out for the first time by measuring decay protons from the isobaric analog states (IAS). Spreading widths of the IAS are deduced from the escape and total widths. The results show a strong isospin dependence which can be explained by the isospin mixing effect due to the coupling to the $T_0$ component among three multiplets ${T=T}_0-1\mathrm{}$, $T_0$, and $T_0+1\mathrm{}$ of isovector monopole states in daughter nuclei. Empirical isospin mixing probabilities are found to be consistent with microscopic sum rule predictions.

The ${\beta }^{+}$-decay half-lives of the neutron-deficient, odd-odd, $N=Z$ nuclei ${}^{74}\mathrm{Rb}$, ${}^{78}\mathrm{Y}$, ${}^{82}\mathrm{Nb}$, and ${}^{86}\mathrm{Tc}$ have been measured following the fragmentation of a primary ${}^{92}\mathrm{Mo}$ beam at an energy of 60 MeV per nucleon. The half-lives were measured by correlating ${\beta }^{+}$ decays with the implantation of unambigously identified fragments. The deduced $\log \mathrm{ft}$ values are consistent with $0^{+}\to 0^{+}$ Fermi superallowed transitions, which together with the measured ${\beta }^{+}$ detection efficiencies suggest $T=1\mathrm{}$, $I^{\pi }{=0\mathrm{}}^{+}$ ground states for these odd-odd, $N=Z$ nuclei. These data represent the heaviest $N=Z$ systems for which Fermi superallowed decays have been established. The results suggest that these nuclei can extend the mass range used to test the conserved vector current hypothesis of the standard model.

The fusion-fission cross section for the system ${}^{17}\mathrm{F}{+}^{208}\mathrm{Pb}$ involving the drip line nucleus ${}^{17}\mathrm{F}$ has been measured at energies in the vicinity of the Coulomb barrier. No enhancement of the fusion-fission yields due to breakup or to a large interaction radius was observed.

A polarized internal atomic-hydrogen target and a stored, polarized beam are used to measure the spin-dependent total cross section $\Delta {\sigma }_T/{\sigma }_{\mathrm{tot}}$ for $\overrightarrow{p}\overrightarrow{p}\to \mathrm{pp}{\pi }^0$, as well as the polar integrals of the spin correlation coefficient combination $A_{\mathrm{xx}}{-A}_{\mathrm{yy}}$, and the analyzing power $A_y$ at four bombarding energies between 325 and 400 MeV. This experiment is made possible by the use of a cooled beam in a storage ring. The polarization observables are used to study the contribution from individual partial waves.

The isotopes ${}^{68–74}\mathrm{Ni}$, of interest both for nuclear physics and astrophysics, have been produced in proton-induced fission of ${}^{238}\mathrm{U}$ and ionized in a laser ion guide coupled to an on-line mass separator. Their $\beta$ decay was studied by means of $\beta$- $\gamma$ and $\gamma$- $\gamma$ spectroscopy. Half-lives have been determined and production cross sections extracted. A partial level scheme is presented for ${}^{73}\mathrm{Cu}$ and additional levels for ${}^{71}\mathrm{Cu}$, providing evidence for a sharply lowered position of the $\pi {1f}_{5/2}$ orbital as occupancy of the $\nu {1g}_{9/2}$ state increases. The latter may have a clear impact on the predicted structure and decay properties of doubly magic ${}^{78}\mathrm{Ni}$.

The cross section for the ${}^3\mathrm{He}\left({e,e}^{\prime }d\right)p$ reaction has been measured for a range of missing momentum $p_m$ at incident electron energies of 370 and 576 MeV and for values of the three-momentum transfer $q$ of 412, 504, and $604\mathrm{MeV}/c$. The longitudinal and transverse structure functions have been separated for $q=412\mathrm{}$ and $504\mathrm{MeV}/c$. The data are compared to exact three-body Faddeev calculations and calculations based on a covariant, gauge-invariant diagrammatic expansion. In general, fair to good agreement is observed, but there are some differences between the data and the calculations, especially for the $q$ dependence and for the transverse structure function $W_T$.

Antiproton production in $11.7A\mathrm{GeV}/c$ $\mathrm{Au}+\mathrm{Au}$ collisions over a wide transverse-mass coverage was studied using the AGS-E866 experimental apparatus. The mean transverse kinetic energy increases as a function of centrality and is similar to that of protons. The antiproton yields in $\mathrm{Si}+\mathrm{Al}$, $\mathrm{Si}+\mathrm{Au}$, and $\mathrm{Au}+\mathrm{Au}$ collisions are consistent with scaling with the 0.7 power of the number of participant nucleons.

Because of the rapidly falling particle spectrum at large $p_T$ from jet fragmentation at CERN SPS energy, the high- $p_T$ hadron distribution should be highly sensitive to parton energy loss inside a dense medium as predicted by recent perturbative QCD (PQCD) studies. A careful analysis of recent data from CERN SPS experiments via PQCD calculation shows little evidence of energy loss. This implies that either the lifetime of the dense partonic matter is very short or one has to rethink parton energy loss in dense matter. The hadronic matter does not seem to cause jet quenching in $\mathrm{Pb}+\mathrm{Pb}$ collisions at the CERN SPS. High- $p_T$ two particle correlation in the azimuthal angle is proposed to further clarify this issue.

The lifetime of the unresolved $\gamma$ transitions forming the rotational quasicontinuum spectrum has been measured for ${}^{164}\mathrm{Yb}$ using the Doppler shift attenuation technique. The fractional Doppler shifts of transitions along the diagonal valley of $E_{{\gamma }_1}\times E_{{\gamma }_2}$ spectra are extracted for the first time using a new technique based on the fluctuation patterns of counts. The rotational collectivity was found to persist with full strength also when the rotational bands are strongly mixed. For the high spin $(I>\mathrm{}20\mathrm{}ħ)$ and energy $(0<\mathrm{}{E}_{\mathrm{ex}}<2\mathrm{}\mathrm{MeV})$ regions there is agreement between the discrete and the damped transitions and with $Q_t\approx 5.5e\mathrm{b}$.

A Comment on the Letter by B. D. Milbrath et al., Phys. Rev. Lett. 80, 452 (1998). The authors of the Letter offer a Reply.

A Reply to the Comment by F. Klein et al.

Using a relativistic hadron transport model, we investigate the utility of the elliptic flow excitation function as a probe for the stiffness of nuclear matter and for the onset of a possible quark-gluon-plasma phase transition at alternating-gradient synchrotron energies $1\lesssim E_{\mathrm{beam}}\lesssim 11A\mathrm{GeV}$. The excitation function shows a strong dependence on the nuclear equation of state, and exhibits characteristic signatures which could signal the onset of the transition.

The effective intercept parameter of the two-pion Bose-Einstein correlation function, ${\lambda }_{*}$, is found to be sensitive to the partial restoration of ${\mathrm{U}}_A\left(1\right)$ symmetry in ultra-relativistic nuclear collisions. An increase in the yield of the ${\eta }^{\prime }$ meson, proposed earlier as a signal of partial ${\mathrm{U}}_A\left(1\right)$ restoration, is shown to create a “hole” in the low $p_t$ region of ${\lambda }_{*}$. A comparison with NA44 data and central $\mathrm{S}+\mathrm{Pb}$ collisions at $200A\mathrm{GeV}$ is made, and implications for future heavy ion experiments are discussed.

In an effort to understand the implications of Coulomb dissociation experiments for the determination of the ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ reaction rate, longitudinal momentum distributions of ${}^7\mathrm{Be}$ fragments produced in the Coulomb dissociation of 44 and 81 MeV/nucleon ${}^8\mathrm{B}$ beams on a Pb target were measured. These distributions are characterized by asymmetries interpreted as the result of interference between $E1\mathrm{}$ and $E2\mathrm{}$ transition amplitudes in the Coulomb breakup. When interpreted in the context of a first order perturbation theory of Coulomb dissociation that assumes a single particle ${}^8\mathrm{B}$ structure model, this measurement yields $S_{E2\mathrm{}}/S_{E1\mathrm{}}{=6.7\mathrm{}}_{-1.9\mathrm{}}^{+2.8\mathrm{}}\times {10}^{-4\mathrm{}}$ at a fragment relative kinetic energy of 0.6 MeV.

The reaction ${}^{16}\mathrm{O}({e,e}^{\prime }\mathrm{pp}{)}^{14}\mathrm{C}$ has been studied at a transferred four-momentum $(\omega ,|\mathbf{q}|)=(210\mathrm{MeV},300\mathrm{}\mathrm{MeV}/c)$. The differential cross sections for the transitions to the ground state and the lowest excited states in ${}^{14}\mathrm{C}$ were determined as a function of the momentum of the recoiling ${}^{14}\mathrm{C}$ nucleus and the angle between the momentum of the proton emitted in the forward direction and the momentum transfer $\mathbf{q}$. A comparison of the data to the results of calculations, performed with a microscopic model, shows clear signatures for short-range correlations in the ${}^{16}\mathrm{O}$ ground state.

A Comment on the Letter by G. Q. Li, C.-H. Lee, and G. E. Brown, Phys. Rev. Lett. 79, 5214 (1997). The authors of the Letter offer a Reply.

A Reply to the Comment by Norman K. Glendenning.

We explore how nuclear modifications to the free nucleon structure functions (also known as shadowing) affect heavy quark production in collisions at different impact parameters. We assume that the nuclear modifications arise from a density dependent effect such as gluon recombination and are thus proportional to the local density. We calculate the dependence of charm and bottom quark production on impact parameter and show that density dependent modifications can lead to significant reductions in the heavy quark production cross sections in central relative to peripheral interactions.

The ${}^1\mathrm{H}\left({e,e}^{\prime }{K}^{+}\right)\Lambda$ reaction was studied as a function of the squared four-momentum transfer, $Q^2$, and the virtual photon polarization, $\varepsilon$. For each of four $Q^2$ settings, 0.52, 0.75, 1.00, and 2.00 $(\mathrm{GeV}/c{)}^2$, the longitudinal and transverse virtual photon cross sections were extracted in measurements at three virtual photon polarizations. The $Q^2$ dependence of the ${\sigma }_L/{\sigma }_T$ ratio differs significantly from current theoretical predictions. This, combined with the precision of the measurement, implies a need for revision of existing calculations.

In heavy-ion collisions and scatterings of $\alpha$ particles from nuclei one encounters a deflection function which has a minimum at a small positive angle. We show that the corresponding scattering amplitude has an angular distribution which behaves as if a forward glory scattering were taking place. This phenomenon can be interpreted semiclassically as the interference between the near- and far-side components in the dark-side of a rainbow scattering.