B (E 1) strengths from Coulomb excitation of 11Be

The B (E 1 ;1 / 2+ → 1 / 2-) strength for 11Be has been extracted from intermediate energy Coulomb excitation measurements, over a range of beam energies using a new reaction model, the extended continuum discretized coupled channels (XCDCC) method. In addition, a measurement of the excitation cross section for 11Be + 208Pb at 38.6 MeV/nucleon is reported. The B (E 1) strength of 0.105(12) e2 fm2 derived from this measurement is consistent with those made previously at 60 and 64 MeV/nucleon, in contrast to an anomalously low result obtained at 43 MeV/nucleon. By coupling a multi-configuration description of the projectile structure with realistic reaction theory, the XCDCC model provides for the first time a fully quantum mechanical description of Coulomb excitation. The XCDCC calculations reveal that the excitation process involves significant contributions from nuclear, continuum, and higher-order effects. An analysis of the present and two earlier intermediate energy measurements yields a combined B(E1) strength of 0.105(7) e2 fm2. This value is in good agreement with the value deduced independently from the lifetime of the 1 / 2- state in 11Be, and has a comparable precision. © 2007 Elsevier B.V. All rights reserved.
SCOPUS: ar.j
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