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HK: Hadronen und Kerne

HK 13: Kernspektroskopie, leichte Kerne I

HK 13.7: Vortrag

Montag, 24. März 1997, 18:45–19:00, HS E

The first observation of the T_z=−7/2 nuclei ⁴⁵Fe and ⁴⁹Ni — •M. Hellström², B. Blank¹, S. Czajkowski¹, F. Davi¹, R. Del Moral¹, J. P. Dufour¹, A. Fleury¹, C. Marchand¹, M. S. Pravikoff¹, J. Benlliure², F. Boué², R. Collatz², A. Heinz², Z. Hu², E. Roeckl², M. Shibata², K. Sümmerer², Z. Janas³, M. Karny³, M. Pfützner³, and M. Lewitowicz⁴ — ¹Centre d’Etudes Nucléaires de Bordeaux-Gradignan, France — ²Gesellschaft für Schwerionenforschung, Darmstadt, Germany — ³Institute of Experimental Physics, University of Warsaw, Poland — ⁴Grand Accélerateur National des Ions Lourds, Caen, France

A primary beam of ⁵⁸Ni at 600 MeV/nucleon from the SIS synchrotron at GSI was used to produce proton-rich isotopes in the titanium-to-nickel region by projectile fragmentation on a beryllium target. The fragments were separated by the projectile-fragment separator FRS and unambiguously identified by means of a TOF-ΔE-Bρ analysis. We report the first observation of the T_z=−7/2 nuclei ⁴⁵Fe and ⁴⁹Ni, the most proton-rich nuclei ever synthesized, with an excess of seven protons. In addition, the new isotope ⁴²Cr (T_z=−3) was identified. According to commonly used mass predictions, these isotopes are all unbound with respect to two-proton emission from their ground states. From the non-observation of ³⁸Ti (T_z=−3) in this experiment, an upper limit of 120 ns is deduced for the half-life of this isotope.