No abstract

The yields of over 200 projectile-like fragments (PLFs) and target-like fragments (TLFs) from the interaction of (E c.m. =450 MeV) 136 Xe with a thick target of 208 Pb were measured using Gammasphere and off-line γ-ray spectroscopy, giving a comprehensive picture of the production cross sections in this reaction.The measured yields were compared to predictions of the GRAZING model and the predictions of Zagrebaev and Greiner using a quantitative metric, the theory evaluation factor, tef. The GRAZING model predictions are adequate for describing the yields of nuclei near the target or projectile but grossly underestimate the yields of all other products. The predictions of Zagrebaev and Greiner correctly describe the magnitude and maxima of the observed TLF transfer cross sections for a wide range of transfers (∆Z = -8 to ∆Z = +2). However for ∆Z =+4, the observed position of the maximum in the distribution is four neutrons richer than the predicted maximum. The predicted yields of the neutron-rich N=126 nuclei exceed the measured values by two orders of magnitude. Correlations between TLF and PLF yields are discussed.

No abstract

No abstract

No 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

Background: The cross section for forming a heavy evaporation residue in fusion reactions depends on the capture cross section, the fusion probability, P CN , i.e., the probability that the projectile-target system will evolve inside the fission saddle point to form a completely fused system rather than re-separating (quasifission), and the survival of the completely fused system against fission. P CN is the least known of these quantities. Methods: We measured the fission fragment angular distributions for these reactions and used the formalism of Back to deduce the fusion-fission and quasifission cross sections. From these quantities we deduced P CN for each reaction. Conclusions:The new measured values of P CN agree roughly with the semi-empirical systematic dependence of P CN upon fissility for excited nuclei.

The yields of 42 projectile-like fragments (PLFs) and fission fragments and 36 targetlike fragments (TLFs) were measured using off-line γ-ray spectroscopy in a thin target experiment involving the 136 Xe + 198 Pt reaction. The center of target beam energy was 760.5 MeV(E c.m. = 450 MeV). The reported yields are compared with those from previous measurements for this reaction and with predictions of the GRAZING, di-nuclear systems (DNS) and Improved Quantum Molecular Dynamics (ImQMD)models. The yields of the TLFs and PLFs are, in general, substantially smaller than those previously observed at a beam energy of 1085 MeV. Neither the GRAZING or DNS models correctly describes the measured TLF and PLF yields in this lower-energy reaction but the ImQMD model describes these yields adequately.