Reaction mechanisms in the 40Ar + 197Au collisions at 35 MeV/nucleon

A Semi-exclusive study of heavy-residue production in the40Ar + Ag reaction at 35 MeV/u incident energy

“…1) is centered at the beam velocity and contains fragmentation and transfer products; the second zone (B) is associated with more relaxed projectile residues (mass <40 a.m.u., velocity smaller than the beam velocity), the third zone (D) can clearly be attributed to target or fusion-like residues (mass> 50 a.m.u., very small velocities); the production of these residues is the main subject of this letter. Between the second and the third zones, only a few events are observed (C); they could result from fission, but a coincidence analysis [6] shows that it cannot be the usual binary fission following complete fusion. The velocity spectrum of the heavy products is compared, in Fig.…”

“…Using a non-fissile system, we expect that the largest part of the reactions with highexcitation energy will lead to evaporation residues. The experimental set-up, already described elsewhere [6], includes a telescope of 4 solid-state detectors located at forward angles, a parallel-plate avalanche counter to look for coincidences due to two body events (fission or deep inelastic collisions) and a large hodoscope wall [7] to detect and identify high-energy light nuclei over a large angular range (3 < 0 < 30 ~ The complete hodoscope is made of 96 scintillators but only 72 were operational for this experiment. Their geometry appears in Fig.…”

Multifragmentation in Heavy-Ion Processes

“…At somewhat higher energies, the incomplete fusion peak in the folding angle distribution disappears (185,188) partly because of the onset of multifragment production, partly because • fission seems to 1 compete less effectively with massive evaporation (187,189,190). At even higher energies, incomplete fusion is substituted by the fireball formation (13,194).…”

“…Perhaps, the experimental approach most widely used has been the determination of the fission-fragment folding angle (127,(181)(182)(183)(184)(185)(186)(187)(188)(189)(190)(191)(192) in reactions induced by an intermediate energy heavy ion on a rather fissionable target, lil<e Au, Thor U. The distribution of folding angles typically shows two peaks, one close to 180°, characteristic of grazing collisions, and another, very broad, at a smaller angle.…”

Fission study for the system84Kr+232Th at 25, 35 and 45 MeV/u

“…With increasing bombarding energy (Ei) this cross section gives way to incomplete fusion [1,2]. At even higher energies the cross section for incomplete fusion becomes highly suppressed [3,4]. As for this evolution, interpretations vary from temperature limitations [5] to dynamic processes [6].…”