DAPNIA-04-218 |
---|
Prolate deformation in the $^{187, 189}$Bi isotopes |
A. Hurstel, Y. Le Coz, E. Bouchez, A. Chatillon,A. G"orgen,P.T. Greenlees, K. Hauschild, S. Juutinen,H. Kettunen, W. Korten,P. Nieminen,M. Rejmund,Ch. Theisen,J. Wilson,A.N. Andreyev,F. Becker,T. Enqvist,P.M. Jones, R. Julin, H. Kankaanpaa, A. Keenan,P. Kuusiniemi, M. Leino, A.-P. Lepp"anen, M. Muikku, J. Pakarinen,P. Rahkila, J. Uusitalo |
Prompt and delayed gamma-ray spectroscopy of very neutron deficient bismuth isotopes $^{187, 189}$Bi has been performed using the recoil decay tagging method. A rotational band has been observed in $^{189}$Bi and is interpreted as a complete decoupling of a single proton from the deformed lead core. The results for $^{187}$Bi suggest a similar structure and coupling scheme. This study gives the first evidence for a prolate band in a light bismuth nucleus and confirms the prolate character of the low-lying rotational band observed in the core nuclei $^{188}$Pb and $^{186}$Pb. |