Long range absorption in the scattering of 6He on 208Pb and 197Au at 27 MeV

Abstract

11 pages, 10 figures.-- PACS nrs.: 25.60.Dz, 25.60.Gc, 25.60.Bx, 21.10.Gv, 27.20.+n.-- 2nd version of the pre-print: Submitted on 18 Jul 2005 (v1), last revised 17 Nov 2005 (this version, v2), minor corrections made.-- Published in: Nuclear Physics A, Vol.765, Issues 3-4, pages 294-306 (6 February 2006). Quasi-elastic scattering of 6He at E_lab=27 MeV from 197Au has been measured in the angular range of 6-72 degrees in the laboratory system employing LEDA and LAMP detection systems. These data, along with previously analysed data of 6He + 208Pb at the same energy, are analyzed using Optical Model calculations. The role of Coulomb dipole polarizability has been investigated. Large imaginary diffuseness parameters are required to fit the data. This result is an evidence for long range absorption mechanisms in 6He induced reactions. The authors thank the staff at the Cyclotron Research Centre accelerator facility in Louvain-la-Neuve, Belgium, for providing us with an intense and good quality radioactive beam. ORK acknowledges a grant from the Iranian government and support from the University of Sevilla for his stay at this university. PJW, TD, ACS, AL, ADP and WBS would like to acknowledge support from the British EPSRC. AMSB, IMB, MVA, AM, MAGA and JGC would like to acknowledge support from the Spanish MCyT under projects FPA2003-05958 and FPA2005-04460. AMSB acknowledges a research grant from the Spanish MCyT. Peer reviewed