Phys. Rev. C 70, 044601 (2004) [10 pages]Direct and compound reactions induced by unstable helium beams near the Coulomb barrierReceived 26 August 2003; revised 1 June 2004; published 6 October 2004 Reactions induced by radioactive 6,8He beams from the SPIRAL facility were studied on 63,65Cu and 188,190,192Os targets and compared to reactions with the stable 4He projectiles from the Mumbai Pelletron. Partial residue cross sections for fusion and neutron transfer obtained from the measured intensities of characteristic in-beam γ rays for the 6He+63,65Cu systems are presented. Coincidence measurements of heavy reaction products, identified by their characteristic γ rays, with projectilelike charged particles, provide direct evidence for a large transfer cross section with Borromean nuclei 6He at 19.5 and 30 MeV and 8He at 27 MeV. Reaction cross sections were also obtained from measured elastic angular distributions for 6,8He+Cu systems. Cross sections for fusion and direct reactions with 4,6He beams on heavier targets of 188,192Os at 30 MeV are also presented. The present work underlines the need to distinguish between various reaction mechanisms leading to the same products before drawing conclusions about the effect of weak binding on the fusion process. The feasibility of extracting small cross sections from inclusive in-beam γ-ray measurements for reaction studies near the Coulomb barrier with low intensity isotope separation on-line beams is highlighted. © 2004 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevC.70.044601
DOI:
10.1103/PhysRevC.70.044601
PACS:
25.60.Pj, 25.60.Je, 25.70.Jj
|
|
About | Terms and Conditions | Subscriptions | Search | Help
Use of the American Physical Society websites and journals implies that the user has read and agrees to our Terms and Conditions and any applicable Subscription Agreement. Physical Review®, Physical Review Letters®, Reviews of Modern Physics®, and Physical Review Special Topics® are trademarks of the American Physical Society.