New type of asymmetric fission in proton-rich nuclei

• Published in: Physical review letters 2010-12, Vol.105 (25), p.252502-252502, Article 252502
• Main Authors: Andreyev, A N, Elseviers, J, Huyse, M, Van Duppen, P, Antalic, S, Barzakh, A, Bree, N, Cocolios, T E, Comas, V F, Diriken, J, Fedorov, D, Fedosseev, V, Franchoo, S, Heredia, J A, Ivanov, O, Köster, U, Marsh, B A, Nishio, K, Page, R D, Patronis, N, Seliverstov, M, Tsekhanovich, I, Van den Bergh, P, Van De Walle, J, Venhart, M, Vermote, S, Veselsky, M, Wagemans, C, Ichikawa, T, Iwamoto, A, Möller, P, Sierk, A J
• Format: Article
• Language: English
• Subjects: ALPHA DECAY RADIOISOTOPES; ASYMMETRY; BARYONS; BETA DECAY; BETA DECAY RADIOISOTOPES; BRANCHING RATIO; CERN; DECAY; DIMENSIONLESS NUMBERS; DISTRIBUTION; ELECTRON CAPTURE RADIOISOTOPES; ELEMENTARY PARTICLES; EVEN-EVEN NUCLEI; FERMIONS; FISSION; FISSION FRAGMENTS; HADRONS; INTERMEDIATE MASS NUCLEI; INTERNATIONAL ORGANIZATIONS; IONIZATION; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; LASERS; MASS; MASS DISTRIBUTION; MERCURY 180; MERCURY ISOTOPES; MILLISECONDS LIVING RADIOISOTOPES; NEUTRON-DEFICIENT ISOTOPES; NEUTRONS; NUCLEAR DECAY; Nuclear Experiment; NUCLEAR FRAGMENTS; NUCLEAR PHYSICS AND RADIATION PHYSICS; NUCLEAR REACTIONS; NUCLEI; NUCLEONS; ODD-ODD NUCLEI; Physics; PROTONS; RADIOISOTOPES; SECONDS LIVING RADIOISOTOPES; SPATIAL DISTRIBUTION; STABLE ISOTOPES; SYMMETRY; THALLIUM 180; THALLIUM ISOTOPES; ZIRCONIUM 90; ZIRCONIUM ISOTOPES
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/physrevlett.105.252502

A very exotic process of β-delayed fission of 180Tl is studied in detail by using resonant laser ionization with subsequent mass separation at ISOLDE (CERN). In contrast to common expectations, the fission-fragment mass distribution of the post-β-decay daughter nucleus 180Hg (N/Z=1.25) is asymmetric. This asymmetry is more surprising since a mass-symmetric split of this extremely neutron-deficient nucleus would lead to two 90Zr fragments, with magic N=50 and semimagic Z=40. This is a new type of asymmetric fission, not caused by large shell effects related to fragment magic proton and neutron numbers, as observed in the actinide region. The newly measured branching ratio for β-delayed fission of 180Tl is 3.6(7) × 10(-3)%, approximately 2 orders of magnitude larger than in an earlier study.