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arXiv · 1402.0406

Isospin properties of electric dipole excitations in 48Ca

V. Derya·D. Savran·J. Endres·M. N. Harakeh·H. Hergert·J. H. Kelley·P. Papakonstantinou·N. Pietralla·V. Yu. Ponomarev·R. Roth·G. Rusev·A. P. Tonchev·W. Tornow·H. J. Wörtche·A. Zilges
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Abstract

Two different experimental approaches were combined to study the electric dipole strength in the doubly-magic nucleus 48Ca below the neutron threshold. Real-photon scattering experiments using bremsstrahlung up to 9.9 MeV and nearly mono-energetic linearly polarized photons with energies between 6.6 and 9.51 MeV provided strength distribution and parities, and an (α,α'γ) experiment at E_α=136 MeV gave cross sections for an isoscalar probe. The unexpected difference observed in the dipole response is compared to calculations using the first-order random-phase approximation and points to an energy-dependent isospin character. A strong isoscalar state at 7.6 MeV was identified for the first time supporting a recent theoretical prediction.

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V. Derya, D. Savran, J. Endres, M. N. Harakeh, H. Hergert, J. H. Kelley, P. Papakonstantinou, N. Pietralla, V. Yu. Ponomarev, R. Roth, G. Rusev, A. P. Tonchev, W. Tornow, H. J. Wörtche, A. Zilges. 2014-02-03. Isospin properties of electric dipole excitations in 48Ca. https://doi.org/10.1016/j.physletb.2014.01.050

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