Time scale for emission of soft ejectiles in the disassembly of hot nuclei

Small-angle relative velocity correlations have been measured for the emission of soft intermediate mass fragments $(0.7\mathrm{}<~E/A<~3.0\mathrm{MeV})$ in high-deposition-energy events produced in the 4.8 GeV ${}^3{\mathrm{H}\mathrm{e}+}^{197}\mathrm{Au}$ reaction. The experimental correlations are compared with an $N$-body Coulomb-trajectory simulation that accounts for the fragment spectra, multiplicity, and charge distributions. In order to reproduce the data, a small residue $(Z\sim 10–20)$ that is located randomly in the breakup volume is required. This analysis indicates breakup time scales of order $\tau =20\mathrm{}–50\mathrm{fm}/c.\mathrm{}$