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HK: Hadronen und Kerne
HK 13: Kernspektroskopie, leichte Kerne I
HK 13.2: Talk
Monday, March 24, 1997, 17:30–17:45, HS E
Search for the γ-decay of the First Excited State of 17Ne — •M.J. Chromik1, M. Thoennessen1, B.A. Brown1, M. Fauerbach1, T. Glasmacher1, R.W. Ibbotson1, H. Scheit1, and P.G. Thirolf2 — 1NSCL, Michigan State University — 2Ludwig Maximilians Universität München
Recent measurements [1] show evidence that the first excited state of 17Ne is bound with respect to one proton emission and unbound with respect to two proton emission. The two proton decay of this state is in direct competition with the γ-ray decay back to the ground-state. In order to set limits on the two-proton branching ratio we measured the γ-ray decay branch by using Coulomb excitation of intermediate energy radioactive beams. The secondary 70 A·MeV 17Ne beam was produced from a primary beam of 100 A·MeV 20Ne and bombarded a 550 mg/cm2 Au target. The γ-rays were detected in a position sensitive array of 40 NaI(Tl) detectors which allowed for the Doppler shift correction. A plastic phoswich ΔE - E detector vetoed nuclear reactions in the target by identifying Z=10 events. We saw evidence for the γ-ray transition from the first excited state of 17Ne located at 1.28 MeV. We will estimate he relativ branching ratio between the two possible decays nodes from the γ-ray yield and the calculated virtual photon spectrum. Supported by the NSF under grant PHY95-28844.
[1] V. Guimaraes, Nucl. Phys. A588, 161c (1995)