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HK: Physik der Hadronen und Kerne
HK 10: Poster Session: Nuclear Structure/Spectroscopy
HK 10.13: Poster
Dienstag, 9. März 2004, 13:30–15:30, Foyer
Direct proof of the |2+⊗ 3−⟩-two phonon character of the 11−-state in 140Ce* — •T. Hartmann1, M. Babilon1,2, R.F. Casten2, J. Hasper1, A. Hecht2, M. Caprio2, and A. Zilges1 — 1Institut für Kernphysik, TU Darmstadt, Germany — 2Physics Department - Wright Nuclear Structure Laboratory, Yale University, New Haven, CT, USA
A (p,p’γ)-experiment has been performed at the ESTU tandem
accelerator
at Yale University using 9 high resolution Ge(HP) Clover-detectors and 4
proton detectors to investigate the decay pattern of the first excited
Jπ=1−-state in 140Ce.
As in its N=82-isotones 142Nd and 144Sm this level is expected
to
be the member of a quintuplett of negative parity states arising from the
coupling of two phonons (21+⊗ 31−) representing surface
oscillations. The two phonon character of this collective isoscalar mode
had
been confirmed for 142Nd and 144Sm, by measuring the branching
ratio
of its decay to the 31−-state,
where the branching ratio is 0.8% and 1.1%, respecitvely [1]. To proof
the
two-phonon character of this state in 140Ce, a branching ratio of only
0.4% had to measured.
* supported by the DFG (SFB 634 and Zi510/2-2) and by the US
DOE
(DE-FG02-91ER-40609)
[1] M. Wilhelm et al., Phys. Rev. C54 (1996) 449R.