Low-lying E1 strength in 20O

E. Tryggestad, T. Baumann, P. Heckman, M. Thoennessen, T. Aumann, D. Bazin, Y. Blumenfeld, J. R. Beene, T. A. Lewis, D. C. Radford, D. Shapira, R. L. Varner, M. Chartier, M. L. Halbert, J. F. Liang

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49 Scopus citations


Intermediate energy Coulomb excitation at 100 MeV/nucleon was used to probe the low-lying level structure of both 18O and 20O in the region between 1 and 8 MeV. Discrete 1- states with energies of 5.35(10) and 6.85(5) MeV were observed in 20O. The strong direct excitation and subsequent γ-ray decay of these states, along with B(Eλ) predictions for 18,20O levels in this energy region, established their dipole character. The extracted B(E1)↑ values of 0.062(16)e2 fm2 and 0.035(9)e2 fm2 for the 5.35- and 6.85-MeV states, respectively, are significantly larger than shell model calculations, though modification of the single-particle energies, in particular, the p-sd shell gap, improves the agreement, The summed B(E1)↑ value for these levels (in Weisskopf units) is consistent with that for other nuclei that have been discussed recently in the literature as potential Pygmy dipole resonance hosts.

Original languageEnglish
Article number064309
Pages (from-to)643091-6430914
Number of pages5787824
JournalPhysical Review C - Nuclear Physics
Issue number6
StatePublished - 1 Jan 2003
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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