Freiburg 1999 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 50: Kernphysik VI / Spaltung
HK 50.6: Vortrag
Donnerstag, 25. März 1999, 15:15–15:30, B
Experimental Evidence for Two-Proton Radioactivity — •P.G. Thirolf1, M.J. Chromik1, M. Thoennessen2, A. Azhari2, J. Brown2, M. Fauerbach2, T. Glasmacher2, R.W. Ibbotson2, R.A. Kryger2, D.J. Morrissey2, H. Scheit2, M. Steiner2, P.J. Woods3, and S. Yokoyama2 — 1Ludwig-Maximilians-Universität München — 2NSCL, Michigan State University — 3University of Edinburgh
17Ne is a promising candidate for the long-searched identification
of a simultaneous two-proton emission, since its first excited state
is bound with respect to the emission of one proton but unbound to the
emission of two protons. The competing γ-decay branch to the ground
state has been measured [1], leaving room for the existence
of a simultaneous two-proton decay branch to 15O.
In an experiment at the K1200 cyclotron at the NSCL (MSU) a secondary
17Ne beam (60 A·MeV) was produced from a primary 20Ne beam
of 100 A·MeV, separated in the A1200 fragment separator and further
purified using a Wien filter. The 17Ne then bombarded a 150 mg/cm2
197Au target, populating the first excited state via Coulomb excitation.
A position sensitive multi-stage particle telescope allowed for a kinematical
complete detection of the scattered projectiles as well as of all decay
products. Sequential 2p-decay could be observed from the decay of
higher-lying states in 17Ne, while at a decay energy around 300 keV
experimental evidence was found for simultaneous two-proton emission from the
first excited state.
[1] M.J. Chromik et al., Phys. Rev. C55 (1997), 1676