Influence of a one-neutron-excess projectile on low-energy incomplete fusion

Abstract

Background: Incomplete fusion has been found to be an important contributor in light heavy-ion (A 20) induced reactions even at slightly above barrier energies. Purpose: For better insight into the dynamics of incomplete fusion, the onset and influence of incomplete fusion need to be investigated in terms of projectile energy (E lab ) and entrance channel mass-asymmetry (μ A ). A rich set of experimental data on incomplete fusion may be useful to correlate the probability of incomplete fusion with the various entrance channel parameters and eventually to develop a theoretical model code for the same. Presently, there is no theoretical model available which can explain low-energy incomplete fusion data consistently. Methods: The excitation functions of complete and incomplete fusion residues populated in the 13 C+ 169 Tm system have been measured using the recoil-catcher activation technique followed by offline γ spectroscopy. The evaporation residues have been identified on the basis of characteristic γ lines and confirmed through the decay-curve analysis. Results: The excitation functions of xn and pxn channels are found to be in good agreement with the statistical model code PACE4; this suggests the population of these channels via complete fusion. Some residues are found to have a contribution from their higher charge isobar precursor decay. The precursor contribution has been deduced from the cumulative cross section using the standard successive radioactive decay formulations. The excitation functions of α-emitting channels are observed to be significantly enhanced as compared to the statistical model code PACE4. This enhancement may be attributed to the contribution from incomplete fusion. The incomplete fusion strength function for 13 C+ 169 Tm is compared with that obtained in the 12 C+ 169 Tm system. It has been found that the one-neutron (1n) excess projectile 13 C (as compared to 12 C) results in a less incomplete fusion contribution due to its relatively large negative alpha-Q value. Recently proposed "alpha-Q-value systematics" seems to explain incomplete fusion data.

Li7 -induced reaction on Monat : A study of complete versus incomplete fusion

“…However, the total fusion (TF) cross section was satisfied by the coupled channel (CC) calculations indicating an insignificant influence of continuum or the transfer channel on TF, whereas, enhancement was observed below the barrier in heavy mass nuclei [1][2][3][4]. Moreover, significant ICF over the CF above the barrier ∼ 4-10 MeV/nucleon in well-bound α-cluster ion induced reactions has also been observed in the α-emitting channels over the past few years [5][6][7][8][9][10]. More experimental investigation is therefore necessary to resolve discrepancies in the dependence of CF-ICF on projectile types at the low incident energies, particularly, for weakly bound nuclei in which breakup yield is more probable in the nuclear force field.…”

“…From the past decade, several efforts were made to study the effects of various entrance channel parameters, like projectile energy and its structure, angular momentum (l) window for ICF, deformation of interacting nuclei, mass asymmetry, α-Q values (Q α ) etc. on the ICF process by the recoil range distribution technique/recoil-catcher activation technique [5][6][7][8][9][10].…”

“…on the ICF process by the recoil range distribution technique/recoil-catcher activation technique [5][6][7][8][9][10].…”

Theoretical analysis of 8Li + 208Pb reaction and the critical angular momentum for complete fusion

“…Complete and incomplete fusion cross sections obtained by using this model are reported in several works (see, for example, Refs. [31][32][33][34][35][36][37][38][39]). However, this approach has being applied only for energies well above the Coulomb barrier, with L crit being independent of the incident energy.…”

Analysis of Fusion Cross Sections in the 9Be Projectile Breakup on Different Target Nuclei

“…According to this model, the CF is a process that occurs at lower angular momenta, and the ICF at higher angular momenta, both processes being separated by a critical angular momentum, L crit , which is the relevant energy-dependent part of the total angular momentum J = L+S (implying that the constraints in J goes along with the corresponding limits established for the "orbital angular momentum quantum number" L). Complete and incomplete fusion cross sections calculated through this model have been reported in several works, such as [23][24][25][26][27][28][29][30], among others. However, being semi-classical, it only applies to higher incident energies above the Coulomb barrier, with L crit being independent of the incident energy.…”