Henderson, J; Heery, J; Rocchini, M; Siciliano, M; Sensharma, N; Ayangeakaa, A D; Janssens, R V F; Kowalewski, T M; Abhishek; Stevenson, P D; Yuksel, E; Brown, B A; Rodriguez, T R; Robledo, L M; Wu, C Y; Kisyov, S; Muller-Gatermann, C; Bildstein, V; Canete, L; Campbell, C M; Carmichael, S; Carpenter, M P; Catford, W N; Copp, P; Cousins, C; Devlin, M; Doherty, D T; Garrett, P E; Garg, U; Gaffney, L P; Hadynska-Klek, K; Hartley, D J; Hicks, S F; Jayatissa, H; Johnson, S R; Kalaydjieva, D; Kondev, F; Lascar, D; Lauritsen, T; Lotay, G; Marchini, N; Matejska-Minda, M; Nandi, S; Nannini, A; O'Shea, C; Pascu, S; Paxman, C J; Perkoff, A; Peters, E E; Podolyak, Zs; Radich, A; Ratod, R; Reed, B J; Regan, P H; Reviol, W; Rubino, E; Russell, R; Seweryniak, D; Vanhoy, J R; Wilson, G L; Wrzosek-Lipska, K; Yates, S W; Zanon, I (2025) Deformation and collectivity in doubly-magic 208Pb. Physical Review Letters, 134. 062502

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Abstract

Lead-208 is the heaviest known doubly-magic nucleus and its structure is therefore of special interest. Despite this magicity, which acts to provide a strong restorative force towards sphericity, it is known to exhibit both strong octupole correlations and some of the strongest quadrupole collectivity observed in doubly-magic systems. In this work, we employ state-of-the-art experimental equipment to conclusively demonstrate, through four Coulomb-excitation measurements, the presence of a large, negative, spectroscopic quadrupole moment for both the vibrational octupole 3−1 and quadrupole 2+ 1 state, indicative of a preference for prolate deformation of the states. These results are compared with three theoretical methods, which are unable to reproduce both the sign and magnitude of this deformation. The observed quadrupole moment has implications for the splitting of the 3− ⊗ 3− two-phonon states, due to the coupling of the quadrupole and octupole motion. Thus, in spite of its well-studied nature, 208Pb remains a puzzle for our understanding of nuclear structure.

Item Type:	Article
Subjects:	Ionising Radiation > Radioactivity
Divisions:	Medical, Marine & Nuclear
Identification number/DOI:	10.1103/PhysRevLett.134.062502
Last Modified:	01 Jul 2025 13:46
URI:	https://eprintspublications.npl.co.uk/id/eprint/10188