학술논문
Lifetime measurements of excited states in 169,171,173Os : Persistence of anomalous B(E2) ratios in transitional rare earth nuclei in the presence of a decoupled i13/2 valence neutron
Document Type
Author
Zhang, W.; Cederwall, B.; Doncel, M.; Aktas; Ertoprak, A.; Liotta, R.; Qi, C.; Grahn, T.; Nara Singh, B. S.; Cullen, D. M.; Hodge, D.; Giles, M.; Stolze, S.; Badran, H.; Braunroth, T.; Calverley, T.; Cox, D. M.; Fang, Y. D.; Greenlees, P. T.; Hilton, J.; Ideguchi, E.; Julin, R.; Juutinen, S.; Kumar Raju, M.; Li, H.; Liu, H.; Matta, S.; Subramaniam, P.; Modamio, V.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Petrache, C. M.; Rahkila, P.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Taylor, M. J.; Uusitalo, J.; Valiente-Dobón, J. J.
Source
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. 820
Subject
Language
English
ISSN
0370-2693
Abstract
Lifetimes of low-lying excited states in the νi13/2+ bands of the neutron-deficient osmium isotopes 169,171,173Os have been measured for the first time using the recoil-distance Doppler shift and recoil-isomer tagging techniques. An unusually low value is observed for the ratio B(E2;21/2+→17/2+)/B(E2;17/2+→13/2+) in 169Os, similar to the “anomalously” low values of the ratio B(E2;41+→21+)/B(E2;21+→0gs+) previously observed in several transitional rare-earth nuclides with even numbers of neutrons and protons, including the neighbouring 168,170Os. Furthermore, the evolution of B(E2;21/2+→17/2+)/B(E2;17/2+→13/2+) with increasing neutron number in the odd-mass isotopic chain 169,171,173Os is observed to follow the same trend as observed previously in the even-even Os isotopes. These findings indicate that the possible quantum phase transition from a seniority conserving structure to a collective regime as a function of neutron number suggested for the even-even systems is maintained in these odd-mass osmium nuclei, with the odd valence neutron merely acting as a “spectator”. As for the even-even nuclei, the phenomenon is highly unexpected for nuclei that are not situated near closed shells.