Observation of fast collinear partitioning of theAu197 +

Aligned breakup of heavy nuclear systems as a new type of deep inelastic collisions at small impact parameters

“…It is shown that the ternary and quaternary breakup reactions occur at extremely inelastic collisions corresponding to small impact parameters, while more peripheral collisions lead to well-known binary deep inelastic reactions. In a Letter [1], followed by a regular article [2], we reported on the observation of a new reaction mode in reseparation of a very heavy nuclear system in 197 Au + 197 Au collisions at 15 MeV/nucleon. In an exclusive-type experiment it was demonstrated that, in addition to the binary (deep inelastic) reaction mode, the colliding system shows a rather exotic process of violent reseparation into three or four massive fragments, nearly aligned along a common reseparation axis.…”

“…From the systematic effect of the deflection of fragments from the reseparation axis, a very short time scale of the breakup process, not exceeding 100 fm/c, was estimated in Refs. [1] and [2].…”

“…In an exclusive-type experiment it was demonstrated that, in addition to the binary (deep inelastic) reaction mode, the colliding system shows a rather exotic process of violent reseparation into three or four massive fragments, nearly aligned along a common reseparation axis. From the systematic effect of the deflection of fragments from the reseparation axis, a very short time scale of the breakup process, not exceeding 100 fm/c, was estimated in Refs.[1] and [2].In this Brief Report we focus our attention on the question of interpretation of the newly observed ternary and quaternary reactions as a new form of deep inelastic reactions (also called dissipative [3] or strongly damped [4] collisions). The experiment was carried out at the Laboratori Nazionali del Sud * wilczynski@ipj.gov.pl (LNS) in Catania.…”

“…For more experimental details see Ref. [2].By using the multidetector CHIMERA array, those events that were nearly completely detected could be kinematically reconstructed. It was found in the experiment that, neglecting emission of light particles (mostly nucleons and α particles, which were assumed to originate from secondary processes of de-excitation of much larger primary fragments), only binary, ternary, and quaternary partition reactions contributed significantly to the balance of the total cross section.…”

Coulomb chronometry to probe the decay mechanism of hot nuclei

“…Only by detecting all reaction products in coincidence and achieving a full kinematical reconstruction event by event can we hope to better understand the underlying reaction and decay mechanisms. Such exclusive experimental data are relatively scarce for multibody exit channels in this energy range [4][5][6][7] leaving room for ambiguities in the interpretation of the reaction mechanism. New theoretical efforts are made to cover this energy range including time dependent microscopic approaches [8,9], transport models [10] and molecular dynamics calculations [11], which require comparison with new exclusive measurements in order to advance.…”