In-beam gamma ray and conversion electron study of Fm250

J. E. Bastin*, R. D. Herzberg, P. A. Butler, G. D. Jones, R. D. Page, D. G. Jenkins, N. Amzal, P. M.T. Brew, N. J. Hammond, R. D. Humphreys, P. J.C. Ikin, T. Page, P. T. Greenlees, P. M. Jones, R. Julin, S. Juutinen, H. Kankaanpää, A. Keenan, H. Kettunen, P. KuusiniemiM. Leino, A. P. Leppänen, M. Muikku, P. Nieminen, P. Rahkila, C. Scholey, J. Uusitalo, E. Bouchez, A. Chatillon, A. Hürstel, W. Korten, Y. Le Coz, Ch Theisen, D. Ackermann, J. Gerl, K. Helariutta, F. P. Hessberger, Ch Schlegel, H. J. Wollerscheim, M. Lach, A. Maj, W. Meczynski, J. Styczen, T. L. Khoo, C. J. Lister, A. V. Afanasjev, H. J. Maier, P. Reiter, P. Bednarczyc, K. Eskola, K. Hauschild

*Corresponding author for this work

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56 Citations (Scopus)

Abstract

We report on a set of in-beam studies of excited states in Fm250. We detected prompt γ rays by using the JUROSPHERE IV array and conversion electrons by using the SACRED spectrometer. Both devices were used in conjunction with the RITU gas-filled recoil separator located at the University of Jyväskylä. Fm250 nuclei were produced through the Hg204(Ca48,2n)Fm250 fusion-evaporation reaction. An experimental excitation function gave a maximum reaction cross section of (980 ± 160) nb at an energy of 209 MeV in the center of the target. Tagging techniques were employed, and a number of E2 transitions were observed that connected the ground-state band levels from spin 4+ up to 18+. The highly converted 4+→2+ transition is observed only by use of conversion electron spectroscopy. The observed ground-state band transitions indicate a rotational structure. We deduce a quadrupole deformation parameter of β2=0.28 ± 0.02. A low-energy background of apparent nuclear origin is observed in conversion electrons and postulated to arise from the decay of high-K bands. The half-life of Fm250 is measured to be 30.4 ± 1.5 min.

Original languageEnglish
Article number024308
JournalPhysical Review C - Nuclear Physics
Volume73
Issue number2
DOIs
Publication statusPublished - 2006
Externally publishedYes

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