No abstract

Double differential cross sections have been measured for energetic p, d, t, and u particles emitted in 0-induced reactions on targets of Al, Zr, and Au at incident energies of 140, 215, and 310 MeV. The energy and angular distributions are well described by isotropic emission from a moving thermal source. The extracted temperature and velocity parameters are found to vary systematically with the incident energy per nucleon above the Coulomb barrier. The observed trends cannot be explained by compound nucleus emission but instead suggest emission from a source which consists of comparable contributions from target and projectile. Alternatively, the proton energy spectra are compared with a precompound model and with a simple knockout model. The d, t, and a-particle cross sections are also described in terms of a generalized coalescence relation which takes into account Coulomb repulsion from the target nucleus. NUCLEAR REACTIONSAl(' O~), E=140, 215, and 310 MeV; Zr(' O~), E =215 and 310 MeV; ' Au('6O~), E =140, 215, and 310 MeV; x =p, d, t, and a. Measured o. (E",O"}. Analysis in terms of moving source, precompound, knockout, and coalescence models.

We present a new expression for the energy of the lowest collective states in even-even nuclei throughout the entire periodic table. Our empirical formula holds universally for all of the natural parity even multipole states and describes the overall trends. This formula depends only on the mass number and the valence nucleon numbers with six parameters. The parameters are determined unambiguously from the data for each multipole state. We discuss the validity of our empirical formula by comparing our results with those of other studies and also by estimating the average and the dispersion of the logarithmic errors of the calculated excitation energies with respect to the measured ones.