Fission of209Bi induced by6He ions

Abstract

Secondary beams of 4He and 6He were produced through the transfer reactions with the 18.5 MeV/u lib and 35.5 MeV/u 7Li primary beams. The fusion-fission cross sections have been measured for the 4.6He + 209Bi reactions at energies Ecm> l.5*Bfus . In the present experiment it was found that the fission excitation function for the neutron rich nuclei 6He is significantly higher than for the 4He nuclei.

Sub-barrier Fusion of Weakly Bound Nuclei

“…A significant enhancement was announced for the 6 He+ 209 Bi fusion reaction compared to the one expected according to the standard model [9,10]. The same was also found at first for sub-barrier fusion of 6 He with 238 U as compared with fusion of 4 He [11].…”

Recent developments in fusion and direct reactions with weakly bound nuclei

“…The pioneer measurements of fusion with radioactive beams were performed in the mid 90's in GANIL, Dubna and Riken [365][366][367], using 11 Be and 6 He beams. Later, in 1998, Kolata et al [146,147] measured the fusion of 6 He + 209 Bi in Notre Dame.…”

Deep Sub-Barrier Fusion Enhancement in theHe6+Pb206Reaction

“…In comparison with the fusion of ordinary nuclei, the breakup and transfer channels with positive Q values could be very important here. The extended ''halo'' structure of exotic nuclei, such as 6 He or 11 Li, may also influence the fusion probability. In Refs.…”

“…The great interest in this type of investigations arose when in 1995 [6] in the study of the fusion-fission cross section for the 6 He 209 Bi reaction, a significant enhancement was observed, especially in the sub-barrier region, compared to the one expected according to the standard model. Soon after the first experimental paper [6], a new series of experiments was undertaken on the near-barrier fusion of 6 He with 209 Bi [7] and 238 U [8] that also announced a significant enhancement of the fusion probabil-ity for 6 He compared to 4 He.…”

“…Soon after the first experimental paper [6], a new series of experiments was undertaken on the near-barrier fusion of 6 He with 209 Bi [7] and 238 U [8] that also announced a significant enhancement of the fusion probabil-ity for 6 He compared to 4 He. However, it is rather difficult to make an unambiguous interpretation of this result.…”