Fusion of radioactiveSn132withNi64

Abstract

Evaporation residue and fission cross sections of radioactive 132 Sn on 64 Ni were measured near the Coulomb barrier. A large subbarrier fusion enhancement was observed. Coupled-channel calculations, including inelastic excitation of the projectile and target, and neutron transfer are in good agreement with the measured fusion excitation function. When the change in nuclear size and shift in barrier height are accounted for, there is no extra fusion enhancement in 132 Sn + 64 Ni with respect to stable Sn + 64 Ni. A systematic comparison of evaporation residue cross sections for the fusion of even 112−124 Sn and 132 Sn with 64 Ni is presented. DOI: 10.1103/PhysRevC.75.054607 PACS number(s): 25.60.−t, 25.60.Pj 0556-2813/2007/75(5)/054607(9) 054607-1

Sub-barrier fusion enhancement with radioactive134Te

“…The calculation was completed using a level density parameter of A/8 MeV −1 , saddle point to ground state level density ratio (a f /a n ) of 1.04, spin distribution diffuseness of 4 , Sierk fission barriers, and experimentally determined masses. This choice of input parameters had been shown to provide good agreement between the pace2 and experimental cross sections for a variety of Sn + Ni reaction systems [29]. The ER cross sections from the pace2 calculations agree well with the experimental data above the Coulomb barrier, which is indicated by the arrow.…”

“…The configuration was identical to that used in Ref. [19], where the distance between the target and third MCP was increased from 169 mm (standard configuration [8,[28][29][30]) to 329 mm to increase the time of flight (ToF) path length.…”

“…The beam, downscaled by 1000, was also counted in the ionization chamber allowing for the ER cross sections to be calculated. Since the energy loss of the beam in the target is about 30 MeV, the effective reaction energy was determined by the fitted spline method [29]. The effective reaction energy will be between the initial beam energy (E in ) and the energy after passing through the target (E out ).…”

“…Below the barrier, where the fusion cross section changes rapidly, the effective reaction energy will be weighted towards E in , as this corresponds to a much higher cross section. The fitted spline method has been tested and shown to provide accurate determination of the effective reaction energies in thick target measurements [29]. The SRIM energy loss code [32] and spline fitting classes from the ROOT software package [33] were used to implement the method.…”

Examining the role of transfer coupling in sub-barrier fusion ofTi46,50+Sn124

“…5 [12,13], and (f) 58,64 Ni+ 132 Sn [10,11] are compared where the reaction energy is shown on a reduced scale using the barrier height predicted by the frozen HF. the larger sub-barrier fusion enhancement has in the past been attributed to the coupling to neutron transfer [5,7,8,26].…”