Target fragment recoil properties were measured using the thick-target—thick-catcher technique for the interaction of 4.8 GeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and 5.0 GeV ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ with ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. The target fragment energies and momenta are very similar for the reaction of 4.8 GeV (400 MeV/nucleon) ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and 5.0 GeV (250 MeV/nucleon) ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ with ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. In the complex variation of fragment momenta with their $\frac{N}{Z}$ ratio, one finds evidence suggesting the existence of several mechanisms leading to the formation of the target fragments. Comparison of these results with the predictions of the intranuclear cascade model of Yariv and Fraenkel and the firestreak model shows that both model predictions grossly overestimate the target fragment momenta.

[NUCLEAR REACTIONS ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},x)$, $E=4.8\mathrm{}$ GeV; ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}({}_{}{}^{20}{}_{}{}^{}\mathrm{Ne},x)$, $E=5.0\mathrm{}$ GeV; measured target fragment recoil properties; deduced target fragment energies, momenta; relativistic heavy ion reactions; target fragmentation; spallation; fission; intranuclear cascade model; firestreak model; thick-target-thick-catcher technique; Ge(Li) gamma-ray spectroscopy.]

• Received 14 October 1980

DOI:https://doi.org/10.1103/PhysRevC.24.464