Emission of intermediate mass fragments during fission

Ternary fission in the reaction ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ + ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ at $E_{\mathrm{lab}}=200\mathrm{}$ MeV has been observed. Intermediate mass fragments (IMF: $3<~Z<~8$) with unique energy and angular distributions have been measured consistent with emission from the neck zone during fission. The widths of the energy spectra are relatively constant for neck fragments with $Z>~4$, suggesting little variability in the scission configurations. A linear dependence of $〈E〉$ on $Z$ is observed for the neck IMFs. The observed trend is compared with a Coulomb trajectory model.