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Particle-particle correlations are studied for large- and small-angle separations for the reactions 312 and 680 MeV $^{40}\mathrm{Ar}$${+}^{\mathrm{nat}}$Ag. The spectral shapes and angular ansiotropies allow a characterization of the effective temperatures and spin zones of the hot nuclear emission sources. Small-angle correlations are compared to reaction simulations that employ various parametrizations for the emission time scales. We conclude that the initial lifetime scale for $^{1,2,3}\mathrm{H}$ particle evaporation is of the order of ${10}^{\mathrm{\ensuremath{-}}22}$ s. These times are so short as to suggest a breakdown of the concept of ``sequential evaporation,'' for which a new ansatz is explored.

Large and small angle correlation measurements are reported for [sup 1]H-[sup 1]H, [sup 4]He-[sup 4]He, and [sup 2]H-[sup 4]He pairs from 7.8[ital A] and 17[ital A] MeV [sup 40]Ar+[sup nat]Ag. These measurements are interpreted with the aid of trajectory calculations designed to simulate evaporationlike emission of particles and fragments. The most important physical parameter needed to fit the correlation function peaks is the fractional yield of unstable fragments ([sup 8]Be or [sup 6]Li) compared to independently evaporated particles ([sup 4]He-[sup 4]He) or ([sup 2]H-[sup 4]He). In this approach, the peaks in the simulated correlation functions contain essentially no information concerning the space-time extent of the emitter source. Nevertheless, these simulations can account for the data very well.

Particle-particle coincidence measurements have been made for the reactions 312 and 680 MeV {sup 40}Ar+{sup nat}Ag. The large-angle correlation data indicate essentially complete energy thermalization even for 680 Mev {sup 40}Ar+{sup nat}Ag. They also allow for an assignment of {approx}64{h bar} for the rms spin and {approx}4.3 MeV for the average initial temperature of the composite nuclei formed by incomplete fusion. The small-angle correlation data for {sup 1}H-{sup 1}H and {sup 2}H-{sup 2}H are consistent with phase-space, statistical-model predictions of the evaporation lifetimes. This result implies that energy mixing and evaporation particle emission steps occur with intervals of {approx}10{sup {minus}22} s, a time period comparable to the traversal time for a projectile velocity of 17 MeV/nucleon.

The /sup 60/Ni nucleus has been studied via the /sup 58/Ni(..cap alpha..,2p..gamma..) reaction at E/sub ..cap alpha../ = 32 MeV using in-beam ..gamma.. spectroscopy techniques. High-spin states up to 10 MeV excitation have been established. Among the five branches depopulating the yrast J/sup ..pi../ = 7/sup -/ state has been found an E3 transition down to the 4/sup +/ state. Comparison with direct reaction results suggests the very likely (..nu..f/sub 5/2/,..nu..g/sub 9/2/)/sub 7/- configuration for the J/sup ..pi../ = 7/sup -/ yrast state at 5349 keV, suggesting then the (..nu..(p/sub 1/2/,p/sub 3/2/,f/sub 5/2/ )/sub 2/+/sup 2/ x (..nu..f/sub 5/2/,..nu..g/sub 9/2/)/sub 7/- /sup 2/)/sub 9/- configuration for the J/sup ..pi../ = 9/sup -/ yrast state. Other high-spin states might be accounted for by the breaking of the /sup 56/Ni core.

The nucleus $^{70}\mathrm{Ge}$ has been studied via the $^{68}\mathrm{Zn}(\ensuremath{\alpha},2n\ensuremath{\gamma})^{70}\mathrm{Ge}$ reaction at ${E}_{\ensuremath{\alpha}}\ensuremath{\simeq}30$ MeV using different in-beam $\ensuremath{\gamma}$ spectroscopic techniques. Levels up to 5.5 MeV have been identified and spins up to ${8}^{+}$ have been established.

Yrast levels of /sup 68/Zn have been investigated via measurements of excitation functions and angular distributions of single ..gamma.. rays and of ..gamma..-..gamma.. coincidences following the /sup 65/Cu(..cap alpha..,p ..gamma..)/sup 68/Zn reaction with ..cap alpha.. particle energies between 12--21 MeV. Spins up to 8h were assigned to observed states. (AIP)

The $^{60}\mathrm{Cu}$ nucleus has been studied via the $^{58}\mathrm{Ni}(\ensuremath{\alpha}, \mathrm{pn}\ensuremath{\gamma})$ reaction using different techniques of in-beam $\ensuremath{\gamma}$ spectroscopy. As in the other odd-odd Cu isotopes, the ${g}_{\frac{9}{2}}$ shell plays an important role for the explanation of observed high-spin states. Some of these (particularly ${6}^{\ensuremath{-}}$ and ${9}^{+}$ states) could be interpreted as two-nucleon states in the framework of a crude shell model.

The presence of a strong discontinuity in the free α−α scattering amplitude at 40 MeV is used as a probe for the identification of α clusters in nuclei. The Li6(α,2α) reaction is investigated at 37.5 and 43.5 MeV with the deuteron as spectator in order to produce quasifree scattering conditions. The distributions measured at these two energies are found to be very different in magnitude as well as in structure, and this phenomenon is attributed to the presence of α−α scattering in the α−Li6 collision. Calculations based on the plane-wave impulse approximation are unable to reproduce the distributions even qualitatively. A calculation based on the graph formalism which takes into account the exact phase-shift amplitude of the free α−α collision fits the two distributions with the same set of parameters. One may conclude that these observations are in favor of the existence of α particles inside the Li6 nucleus.