Studies of heavy ion reactions around Coulomb barrier

Abstract

Dependence of heavy-ion fusion reaction on nuclear deformation and nuclear shell structure AIP Conf.Abstract. The angular distributions of fission fragments for the 32 S+ 184 W reaction near Coulomb barrier energies were measured. The experimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasifission and fast fission contributions by the dinuclear system model. The hindrance to complete fusion both at small and large collision energies is explained. The fusion excitation functions of 32 S+ 90,96 Zr in an energy range from above to below Coulomb barrier were measured and analyzed. The obvious effect of positive Q-value neutron transfers has been observed in the 32 S+ 96 Zr system. In addition, the excitation functions of quasielastic scattering at a backward angle have been measured for the systems of 16 O + 208 Pb, 196 Pt, 184 W, and 154,152 Sm at energies well below the Coulomb barrier. Considering the coupling effects, the extracted diffuseness parameters are close to the values extracted from the systematic analysis of elastic and inelastic scattering data.

Coupled-Channel Effects in Collisions Between Heavy Ions Near the Coulomb Barrier

“…The present full CC analysis of 32 S + 96 Zr fusion data [23,30] using NTFus [29] confirms perfectly well first previous CC calculations [10] describing well the earlier 40 Ca + 90,96 Zr fusion data [9] and, secondly, very recent fragment-γ coincidences measured for 40 Ca + 96 Zr multi-neutron transfer channels [35].…”

“…A new CC computer code named NTFus [29] taking the neutron transfer channels into account in the framework of the semiclassical model of Zagrebaev [10] has been developed. The effect of the neutron transfer channels yields a fairly good agreement with the data of sub-barrier fusion cross sections measured for 32 S + 96 Zr, the more neutron-rich reaction [23].…”

“…1 along with the negative Q-values of their corresponding neutron transfer channels lead us to speculate with the absence of a neutron transfer effect on the sub-barrier fusion for this reaction. With the semiclassical model developed by Zagrebaev [10] we propose to definitively demonstrate the significant role of neutron transfers for the 32 S + 96 Zr fusion reaction by fitting its experimental excitation function with NTFUS code [29] calculations, as shown in Fig. 3.…”

“…The new oriented object NTFUS code [29], using the Zagrebaev model [10] was implemented (at the CIAE) in C++, using the compiler of ROOT [31], following the basic equations of Ref. [32].…”

“…In order to introduce the role of neutron transfers, the NTFUS code [29] applies the Za-grebaev model [10] to calculate the fusion cross sections σ f us (E) as a function of center-of-mass energy E. Then the fusion excitation function can be derived using the following formula [10]:…”