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HK: Physik der Hadronen und Kerne

HK 2: Kernphysik/Spektroskopie I

HK 2.7: Vortrag

Montag, 17. März 2003, 17:45–18:00, A

Decay of Hs-269 and evidence for the N=162 nuclide Hs-270 — •M. Schädel¹, Ch. E. Düllmann^2,3, A. Türler^2,3,4, H.W. Gäggeler^2,3, U.W. Kirbach⁵, A.B. Yakushev^6,4, W. Brüchle¹, R. Dressler², K. Eberhardt⁷, B. Eichler², R. Eichler¹, T.N. Ginter⁵, F. Glaus², K.E. Gregorich⁵, D.C. Hofmann^5,8, E. Jäger¹, D.T. Jost², D.M. Lee⁵, H. Nitsche^5,8, J.B. Patin^5,8, V. Pershina¹, D. Piquet², Z. Qin⁹, B. Schausten¹, E. Schimpf¹, H.-J. Schött¹, S. Soverna^2,3, R. Sudowe⁵, P. Thörle⁷, S.N. Timokhin⁶, N. Trautmann⁷, A. Vahle¹⁰, G. Wirth¹, and P. Zielinski^5,8 — ¹GSI, Darmstadt, D — ²PSI, Villigen, CH — ³Univ. Bern, Bern, CH — ⁴now: TU, München, D — ⁵LBNL, Berkeley, CA — ⁶FLNR, Dubna, RU — ⁷Univ. Mainz, D — ⁸Univ. of California, Berkeley, CA — ⁹IMP, Lanzhou, CN — ¹⁰FZ, Rossendorf, D

We present results form nuclear decays observed after the first chemical separation and characterization of element 108, hassium (Hs)[1,2]. Hs-269 and Hs-270 were synthesized at the UNILAC in hot-fusion reactions of Mg-26 + Cm-248, and were identified by observing genetically linked nuclear decays. Three chains originating from Hs-269 confirmed decay properties of the A=277 nuclide of element 112, observed in the discovery experiment, and they also exhibited a new picture of the Rf-261 decay. Two chains exhibited characteristics expected for the new N=162 shell-closure nuclide Hs-270. >From the measured decay energy of 9.16 MeV an alpha half-life of 3.6 s was estimated.

1. Ch. Düllmann et al. Nature 418 (2002) 859.

2. A. Türler et al. Eur. Phys. J. A, submitted 2002.