Effect of projectile structure on evaporation residue yields in incomplete fusion reactions

Abstract

The excitation functions of heavy residues, representing complete and incomplete fusion products, produced in the reaction of 12C and 13C on 181Ta have been measured over the projectile energy range of 5 to 6.5 MeV/nucleon by the recoil catcher method and off-line γ-ray spectrometry. Comparison of the measured excitation functions with those calculated using the PACE2 code based on the statistical model revealed the occurrence of incomplete fusion reactions in the formation of α emission products. The fraction of incomplete fusion cross sections in the 12C + 181Ta reaction was found to be higher, by a factor of ∼2, than that in the 13C + 181Ta reaction. The results have been discussed in terms of the effect of alpha cluster structure of the projectile on incomplete fusion reactions.

Investigation of the influence of incomplete fusion on complete fusion of16O induced reactions at moderate excitation energies

“…Figures 4(b) and 5 show the EFs for the residues 52 Mn, 51 Cr and 48 V populated by the channels (2α,n) (2α,pn) and (3α,n). It can be seen from the figures that measured excitation functions are much higher but in the same trend as the theoretically calculated values, which can be explained by assuming that these channels are populated not only by CF but also with ICF of 8 Be fragment (in case of 52 Mn and 51 Cr) and 12 C fragment (in case of 48 V) of projectile to the target.…”

“…An agreement between theoretical and experimental values exists at 73.2 ± 2.8 MeV and above this energy significant enhancement of cross-section is found. This simply indicates that 57 Co is populated via CF and ICF of 8 Be fragment both. Regarding the residues 56 Co, 55 Co , 52 Fe and 54 Mn, populated through (α,n), (α,2n), (α,p4n), and (α,2pn) channels, it is obvious from figures 3(b -d) and figure 4(a) that our measured cross-sections are higher than the theoretical predictions.…”

“…Hence, at relatively higher projectile energies and at larger impact parameters, CF moderately gives way to ICF, where fractional mass and charge as well as the linear momentum of projectile are transferred to the target nucleus, due to the prompt emission of α-clusters in the forward cone with almost projectile energy. The studies of coincidence relationships between the outgoing α-particles and the discrete γ-rays of the heavy residues unambiguously has also proved that in these reactions a massive part of the projectile fuses with the target while that remaining escapes at forward angles carrying a large part of the kinetic energy and angular momentum [8]. Furthermore, a few reports [9][10][11] have shown that the population of low-spin states are observed to be hindered and/or less fed in the case of ICF.…”

Incomplete fusion studies near Coulomb barrier: a modified sum rule model

“…Breakup fusion model by Udagawa and Tamura [5], pre-equilibrium emission particle model by Bondorf et al [6], multistep direct reaction theory by Zegrebaev et al [7], and sum rule model by Wilczyński et al [1] are some of them. But none of them could satisfactorily explain all the observations associated with the ICF reactions, in particular, at low beam energy [8].…”

“…From the experimental finding of the enhancement in the cross section of the iodine and antimony isotopes, we inferred that their production was largely due to ICF reactions, i.e. the pre-equilibrium emission of  and 2 (or 8 Be) ejectiles, respectively. Since, the experimental cross sections of iodine and antimony isotopes have contribution from both ICF and CF reactions, the ICF contribution was extracted by subtracting the CF cross section obtained by the PACE4 from the experimental values.…”