Fusion of radioactive 132^{132}Sn with 64^{64}Ni

Evaporation residue and fission cross sections of radioactive $^{132}$Sn on $^{64}$Ni were measured near the Coulomb barrier. A large sub-barrier 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.Comment: 9 pages, 11 figure

The interaction of 11Li with 208Pb

Background: 11Li is one of the most studied halo nuclei. The fusion of 11Li with 208Pb has been the subject of a number of theoretical studies with widely differing predictions, ranging over four orders of magnitude, for the fusion excitation function. Purpose: To measure the excitation function for the 11Li + 208Pb reaction. Methods: A stacked foil/degrader assembly of 208Pb targets was irradiated with a 11Li beam producing center of target beam energies from above barrier to near barrier energies (40 to 29 MeV). The intensity of the 11Li beam (chopped) was 1250 p/s and the beam on-target time was 34 hours. The alpha-decay of the stopped evaporation residues was detected in a alpha-detector array at each beam energy in the beam-off period (the beam was on for <= 5 ns and then off for 170 ns). Results: The 215At evaporation residues were associated with the fusion of 11Li with 208Pb. The 213,214At evaporation residues were formed by the breakup of 11Li into 9Li + 2n, with the 9Li fusing with 208Pb. The 214At evaporation residue appears to result from a "quasi-breakup" process. Conclusions: Most of 11Li + 208Pb interactions lead to breakup with a small fraction (<= 11%) leading to complete fusion.Comment: 25 pages, 11 figure

Cross Section Limits for the 208^{208}Pb(86^{86}Kr,n)293^{293}118 Reaction

In April-May, 2001, the previously reported experiment to synthesize element 118 using the $^{208}$Pb($^{86}$Kr,n)$^{293}$118 reaction was repeated. No events corresponding to the synthesis of element 118 were observed with a total beam dose of 2.6 x 10$^{18}$ ions. The simple upper limit cross sections (1 event) were 0.9 and 0.6 pb for evaporation residue magnetic rigidities of 2.00 $T m$ and 2.12 $T m$, respectively. A more detailed cross section calculation, accounting for an assumed narrow excitation function, the energy loss of the beam in traversing the target and the uncertainty in the magnetic rigidity of the Z=118 recoils is also presented. Re-analysis of the primary data files from the 1999 experiment showed the reported element 118 events are not in the original data. The current results put constraints on the production cross section for synthesis of very heavy nuclei in cold fusion reactions.Comment: 7 pages, 2 figures. Submitted to EPJ