Double differential cross sections have been measured for energetic $p$, $d$, $t$, and $\alpha$ particles emitted in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$-induced reactions on targets of A1, 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 $\alpha$-particle cross sections are also described in terms of a generalized coalescence relation which takes into account Coulomb repulsion from the target nucleus.

NUCLEAR REACTIONS ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$,$x$), $E=140, 215, \mathrm{and} 310$ MeV; ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$,$x$), $E=215\mathrm{} \mathrm{and} 310$ MeV; ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$,$x$), $E=140, 215, \mathrm{and} 310$ MeV; $x=p, d, t, \mathrm{and} \alpha$. Measured $\sigma (E_x,{\theta }_x)$. Analysis in terms of moving source, precompound, knockout, and coalescence models.

• Received 20 November 1981

DOI:https://doi.org/10.1103/PhysRevC.25.2361