Fusion Excitation Research Articles

Analysis of complete, incomplete and total fusion data of 9Be +169Tm, 187Re, 209Bi reactions

We have analyzed the incomplete fusion (ICF), complete fusion (CF) and total fusion (TF) excitation functions for reactions induced by [Formula: see text] on [Formula: see text], [Formula: see text] and [Formula: see text] targets at near barrier energies using Wong’s formula in conjunction with the energy dependent Woods–Saxon potential. A phenomenological selection function is proposed to separate out the contribution of ICF and CF cross-sections in TF cross-section. The variation of relative contribution of ICF and CF in TF with respect to incident beam energy is very well reproduced through this approach.

Reduction Methods for Total Reaction Cross Sections

The most frequently used methods to reduce fusion and total reaction excitation functions were investigated in a very recent paper Canto et al. (Phys Rev C 92:014626, 2015). These methods are widely used to eliminate the influence of masses and charges in comparisons of cross sections for weakly bound and tightly bound systems. This study reached two main conclusions. The first is that the fusion function method is the most successful procedure to reduce fusion cross sections. Applying this method to theoretical cross sections of single channel calculations, one obtains a system independent curve (the fusion function), that can be used as a benchmark to fusion data. The second conclusion was that none of the reduction methods available in the literature is able to provide a universal curve for total reaction cross sections. The reduced single channel cross sections keep a strong dependence of the atomic and mass numbers of the collision partners, except for systems in the same mass range. In the present work we pursue this problem further, applying the reduction methods to systems within a limited mass range. We show that, under these circumstances, the reduction of reaction data may be very useful.

Measurement of fusion excitation function for7Li+64Ni near the barrier

Total fusion (TF) excitation function has been measured for the system 7 Li + 64 Ni at the energies near the Coulomb barrier of the system. The evaporation residue (ER) cross sections have been estimated through the online detection of characteristic γ-rays of the ERs. The summed ER cross sections yielding the experimental TF cross section have been compared with the theoretical one dimensional barrier penetration model (1DBPM) prediction. The measured and the model cross sections are very close to each other at above barrier energies. However, an enhancement of the experimental TF cross section with respect to the 1DBPM prediction is observed at below barrier energies. Coupled channels (CC) calculation with inelastic excitations alone could not explain the enhancement. The origin of the enhancement is identified as due to the enhanced population of the αxn channels. A complete understanding of the effect of direct reaction channels like, breakup or transfer followed by breakup on fusion of weakly bound systems at near barrier energies is of primary importance [1, 2]. In case of fusion of weakly bound stable projectiles like, 6 Li (Sα =1 .47 MeV), 7 Li (Sα =

Role of neutron transfer in asymmetric fusion reactions at sub-barrier energies

The measured complete fusion (capture) excitation function is presented for the 28Si + 208Pb reaction at deep sub-barrier energies. This excitation function is compared with the one predicted with the quantum diffusion approach.

Coupled channel effect in elastic scattering and fusion for6,7Li+28Si

The fusion excitation and elastic angular distribution were measured for 6,7 Li+28 Si from below to above Coulomb barrier (≤ 3Vb ) energies. The barrier distribution derived from the fusion data was found to be broad and asymmetric at the sub-barrier region, compared to 1D BPM estimation. Effect of rotational coupling on fusion was found to be not so dominant. Phenomenological optical potential parameters, with surface and volume type imaginary potentials, were obtained from f tting of elastic scattering data and energy dependence of real and imaginary surface strengths were investigated around the barrier. CDCC calculations considering only breakup of projectile were performed for 6,7 Li+28 Si with the elastic scattering data, using the code FRESCO. The effects of breakup of projectile on elastic cross section do not agree with the energy dependence of real and imaginary strength with volume type imaginary potential around the barrier.

Role of gluon-jet fragmentation in heavy-quark production by hadrons

The role of perturbative gluon-jet fragmentation g..-->..QQ-bar in heavy-quark production by hadrons is quantitatively assessed with respect to the more conventional mechanisms of fusion and flavor excitation. At the energy of the CERN pp-bar collider this contribution is found to give approx.20% of the inclusive large-p/sub T/ muon yield, and approx.(1/3) of the opposite-sign dimuons. The bulk of the associated event structure is not very different from that of the other heavy-quark contributions combined, as far as decay leptons are concerned.