PT Journal
AU Ralet, Dea
   Gadea, A
   Perez, RM
TI Evidence of octupole-phonons at high spin in Pb-207<bold> </bold>
SO Physics Letters B
JI Phys. Lett. B
PY 2019
BP 134797
EP 6pp
VL 797
DI 10.1016/j.physletb.2019.134797
LA English
DE AGATA spectrometer; gamma-Ray tracking; VAMOS plus plus spectrometer; Plunger device; Nuclear deformation; Octupole phonon
AB A lifetime measurement of the 19/2(-) state in Pb-207 has been performed using the Recoil Distance Doppler-Shift (RDDS) method. The nuclei of interest were produced in multi-nucleon transfer reactions induced by a Pb-208 beam impinging on a Mo-100 enriched target. The beam-like nuclei were detected<bold> </bold>and identified in terms of their atomic mass number in the VAMOS++ spectrometer while the prompt gamma rays were detected by the AGATA tracking array. The measured large reduced transition probability B(E3, 19/2(-) -> 13/2(+)) = 40(8) W.u. is the first indication of the octupole phonon at high spin in Pb-207. An analysis in terms of a particle-octupole-vibration coupling model indicates that the measured B(E3) value in Pb-207 is compatible with the contributions from single-phonon and single particle E3 as well as E3 strength arising from the double-octupole-phonon 6(+) state, all adding coherently. A crucial aspect of the coupling model, namely the strong mixing between single-hole and the phonon-hole states, is confirmed in a realistic shell-model calculation.
ER