B(E1) Strengths from Coulomb Excitation of $^{11}$Be

Abstract : The $B$(E1;$1/2^+\to1/2^-$) strength for $^{11}$Be 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 $^{11}$Be+$^{208}$Pb at 38.6 MeV/nucleon is reported. The $B$(E1) strength of 0.105(12) e$^2$fm$^2$ derived from this measurement is consistent with those made previously at 60 and 64 MeV/nucleon, i n 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) e$^2$fm$^2$. This value is in good agreement with the value deduced independently from the lifetime of the $1/2^-$ state in $^{11}$Be, and has a comparable p recision.
Document type :
Journal articles

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Submitted on : Friday, May 25, 2007 - 3:27:02 PM
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Citation

N. C. Summers, S. D. Pain, N.A. Orr, W.N. Catford, J.C. Angélique, et al.. B(E1) Strengths from Coulomb Excitation of $^{11}$Be. Physics Letters B, Elsevier, 2007, 650, pp.124-128. ⟨10.1016/j.physletb.2007.05.003⟩. ⟨in2p3-00149418⟩

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