4π studies of the 1.8–4.8 GeV ³He+^natAg, ¹⁹⁷Au reactions. I. Energy deposition

The Indiana Silicon Sphere 4π detector has been used to measure light-charged particles and intermediate-mass fragments (IMFs) emitted in the 18–4.8 GeV ³He+^natAg, ¹⁹⁷Au reactions. Ejectile multiplicity and total event kinetic energy distributions scale systematically with projectile energy and target mass, except for the ^natAg target at 3.6 and 4.8 GeV. For this system, a saturation in deposition energy is indicated by the data, suggesting the upper projectile energy for stopping has been reached. Maximum deposition energies of ∼950 MeV for the ^natAg target and ∼1600 MeV for the ¹⁹⁷Au target are inferred from the data. The results also demonstrate the importance of accounting for fast cascade processes in defining the excitation energy of the targetlike residue. Correlations between various observables and the average IMF multiplicity indicate that the total thermal energy and total observed charge provide useful gauges of the excitation energy of the fragmenting system. Comparison of the experimental distributions with intranuclear cascade predictions shows qualitative agreement. © 1996 The American Physical Society.