Fine Structure in the alpha decays of $^{226}$U and $^{230}$Pu

P.T. Greenlees - et al.

doi:doi:10.1007/s100500050345

2021 Impact factor 3.131

Hadrons and Nuclei

Eur. Phys. J. A 6, 269-273

Fine Structure in the alpha decays of ²²⁶U and ²³⁰Pu

P.T. Greenlees¹ - P. Kuusiniemi² - N. Amzal¹ - A. Andreyev³ - P.A. Butler¹ - K.J. Cann¹ - J.F.C. Cocks^1,2 - O. Dorvaux² - T. Enqvist^2,7 - P. Fallon⁴ - B. Gall⁶ - M. Guttormsen⁵ - D. Hawcroft¹ - K. Helariutta² - F.P. Hessberger⁷ - F. Hoellinger⁶ - G.D. Jones¹ - P. Jones² - R. Julin² - S. Juutinen² - H. Kankaanpää² - H. Kettunen² - M. Leino² - S. Messelt⁵ - M. Muikku² - S. Ødegå rd⁵ - R.D. Page¹ - A. Savelius² - A. Schiller⁵ - S. Siem⁵ - W.H. Trzaska² - T. Tveter⁵ - J. Uusitalo²

¹ Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE, UK
² Department of Physics, University of Jyväskylä, 40351 Jyväskylä, Finland
³ Joint Institute for Nuclear Research, 141980 Dubna, Russia
⁴ Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
⁵ Department of Physics, University of Oslo, 0316 Oslo, Norway
⁶ Centre de Recherches Nucléaires, 67037 Strasbourg Cedex, France
⁷ Gesellschaft für Schwerionenforschung, 64220 Darmstadt, Germany

Received: 13 April 1999 / Revised version: 07 July 1999 Communicated by J. Äystö

Abstract
The nuclei ²²⁶U and ²³⁰Pu have been populated via reactions involving ²⁰⁸Pb targets bombarded by ²²Ne and ²⁶Mg projectiles. Fusion-evaporation residues were separated in-flight using a gas-filled recoil separator. A position-sensitive Si-strip detector was employed at the focal plane in order to identify correlated $\alpha$ -decay chains. Two fine structure $\alpha$ -decay lines have been observed. The first, with an energy of 7385(5) keV, is assigned as the $\alpha$ decay from ²²⁶U to the first excited 2⁺ state of ²²²Th. The second line, observed for the first time in this work, has an energy of 6961(30) keV and is assigned as the $\alpha$ decay from ²³⁰Pu to the first excited 2⁺ state of ²²⁶U. The excitation energy of the first excited 2⁺ state in ²²⁶U was determined to be 96(25) keV, giving an estimate of the deformation parameter $\beta_{2}\simeq$ 0.20.