Populations of excited states and reaction mechanisms in the emission of complex fragments for collisions ofNi58

Emission of intermediate mass fragments from hot116Ba* formed in low-energy58Ni +58Ni reaction

“…[13,14]. In other words, we use a complete temperature-dependent potential and apply it to the medium-mass, hot compound system 116 Ba * formed in 58 Ni+ 58 Ni reaction at various (low) incident energies [2,15,16,17]. Also, some of the specific data [2,15] chosen here, and discussed in the following paragraph, was not analysed in our earlier work [10].…”

“…complex fragments with masses lighter than A<20, are emitted from both the light (A∼60) and medium-mass (A∼110) compound systems, and may arise as multiple "clusters", and are accompanied by multiple light particles (Z≤2) production. This light-particle emission, associated with evaporation residues production, is very satisfactorily understood as the fusion-evaporation process from an equiliberated compound nucleus in the statistical Hauser-Feshbach formalism [1,2,3,4,5], described in evaporation codes such as LILITA and CASCADE or many other codes. The Hauser-Feshbach formalism has been extended to include the above noted observed complex IMFs, for example in the BUSCO code [2] or in the Extended Hauser-Feshbach Method based on the scission-point picture [5].…”

“…This light-particle emission, associated with evaporation residues production, is very satisfactorily understood as the fusion-evaporation process from an equiliberated compound nucleus in the statistical Hauser-Feshbach formalism [1,2,3,4,5], described in evaporation codes such as LILITA and CASCADE or many other codes. The Hauser-Feshbach formalism has been extended to include the above noted observed complex IMFs, for example in the BUSCO code [2] or in the Extended Hauser-Feshbach Method based on the scission-point picture [5]. An alternative process for the IMFs production is the binary decay of a compound nucleus in the statistical fission model of Moretto [6] or of Vandenbosch and Huizenga [7].…”

“…The data chosen to test our model calculations in the following are the IMFs production cross sections, measured in (i) the 630 MeV 58 Ni+ 58 Ni→ 116 Ba * reaction [2,15], whose kinematical analysis of fragments (the similarity of Gaussian shaped energy spectra of fragments in coincidence with γ rays, and the flat angular distribution of their ground and excited states) revealed that the IMFs with 4≤Z≤9 are consistent with the decay of a compound nucleus formed in a complete fusion reaction and that the effective temperature of the emitting system, estimated on the basis of a simple statistical approach for primary fragments, is on the average about 2.2 MeV, which is about half of the compound nucleus temperature T (=4.42 MeV, based on Eq. (13) below); and (ii) the 348, 371 and 394 MeV 58 Ni+ 58 Ni reaction [17], where the pure Hauser-Feshbach BUSCO predictions do not match the measured cross sections (the same code is used with a reasonable success for the above mentioned data at 630 MeV [2,15]).…”

“…In other words, we use a complete temperature-dependent potential and apply it to the medium-mass, hot compound system 116 Ba * formed in 58 Ni+ 58 Ni reaction at various (low) incident energies [2,15,16,17]. Also, some of the specific data [2,15] chosen here, and discussed in the following paragraph, was not analysed in our earlier work [10]. This system has been of much interest from the point of view of the exotic 12 C (or 100 Sn) cluster radioactivity [17,18,19,20,21], first expected as a ground-state decay [18,19,20,21], but now seems to have observable yields only for the decay of the corresponding excited compound system [17].…”