2020

Ertoprak, A.; Cederwall, B.; Qi, C.; Aktas, Ö.; Doncel, M.; Hadinia, B.; Liotta, R.; Sandzelius, M.; Scholey, C.; Andgren, K.; Bäck, T.; Badran, H.; Braunroth, T.; Calverley, T.; Cox, D. M.; Cullen, D. M.; Fang, Y. D.; Ganioğlu, E.; Giles, M.; Gomez Hornillos, M. B.; Grahn, T.; Greenlees, P. T.; Hilton, J.; Hodge, D.; Ideguchi, E.; Jakobsson, U.; Johnson, A.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Khaplanov, A.; Kumar Raju, M.; Leino, M.; Li, H.; Liu, H.; Matta, S.; Modamio, V.; Nara Singh, B. S.; Niikura, M.; Nyman, M.; Özgür, I.; Page, R. D.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Paul, E. S.; Petrache, C. M.; Peura, P.; Rahkila, P.; Ruotsalainen, P.; Sarén, J.; Sorri, J.; Stolze, S.; Subramaniam, P.; Taylor, M. J.; Uusitalo, J.; Valiente-Dobón, J. J.; Wyss, R.

Excited states in the extremely neutron-deficient nucleus 172Pt were populated via 96Ru(78Kr, 2p) and 92Mo(83Kr, 3n) reactions. The level scheme has been extended up to an excitation energy of ≈ 5 MeV and tentative spin-parity assignments up to I π = 18+. Linear polarization and angular distribution measurements were used to determine the electromagnetic E1 character of the dipole transitions connecting the positive-parity ground-state band with an excited side-band, firmly establishing it as a negativeparity band. The lowest member of this negative-parity structure was firmly assigned spin-parity 3−. In addition, we observed an E3 transition from this 3− state to the ground state, providing direct evidence for octupole collectivity in 172Pt. Large-scale shell model (LSSM) and total Routhian surface (TRS) calculations have been performed, supporting the interpretation of the 3− state as a collective octupolevibrational state.