New experimental access to the two-phonon octupole vibration in 208Pb

Abstract

The feasibility of a new experimental method to identify two-phonon octupole vibrations is investigated for the example of 208Pb. The 2 + member of the 3 I − ⊗ 3 I − multiplet can be excited with the (γ, γ′) reaction and a sizable E1 decay to the 3 I − level serves as a signature of the two-phonon character. Numerical estimates within the quasiparticle-phonon model indicate that such an experiment should be possible with state-of-the-art large volume Ge detectors like the EUROBALL cluster module.