Evidence of octupole-phonons at high spin in $^{207}$Pb

• Published in: Physics letters. B 2019-10, Vol.797
• Main Authors: Ralet, D., Clément, E., Georgiev, G., Stuchbery, A.E., Rejmund, M., van Isacker, P., de France, G., Lemasson, A., Ljungvall, J., Michelagnoli, C., Navin, A., Balabanski, D.L., Atanasova, L., Blazhev, A., Bocchi, G., Carroll, R., Dudouet, J., Dupont, E., Fornal, B., Franchoo, S., Fransen, C., Müller-Gatermann, C., Goasduff, A., Gadea, A., John, P.R., Kocheva, D., Konstantinopoulos, T., Korichi, A., Kusoglu, A., Lenzi, S.M., Leoni, S., Lozeva, R., Maj, A., Perez, R., Pietralla, N., Shand, C., Stezowski, O., Wilmsen, D., Yordanov, D., Barrientos, D., Bednarczyk, P., Birkenbach, B., Boston, A.J., Boston, H.C., Burrows, I., Cederwall, B., Ciemala, M., Collado, J., Crespi, F., Cullen, D., Eberth, H.J., Goupil, J., Harkness, L., Hess, H., Jungclaus, A., Korten, W., Labiche, M., Menegazzo, R., Mengoni, D., Million, B., Nyberg, J., Podolyák, Zs, Pullia, A., Quintana Arnés, B., Recchia, F., Reiter, P., Saillant, F., Salsac, M.D., Sanchis, E., Theisen, C., Valiente Dobon, J.J., Wieland, O.
• Format: Article
• Language: English
• Subjects: Nuclear Experiment; Physics
• ISSN: 0370-2693
• DOI: 10.1016/j.physletb.2019.134797

A lifetime measurement of the 19/2− state in 207 Pb 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 208 Pb beam impinging on a 100 Mo enriched target. The beam-like nuclei were detected and identified in terms of their atomic mass number in the VAMOS++ spectrometer while the prompt γ 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 207 Pb. An analysis in terms of a particle-octupole-vibration coupling model indicates that the measured B(E3) value in 207 Pb is compatible with the contributions from single-phonon and single particle E 3 as well as E 3 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.