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RESEARCH PRODUCT

In-Beam Study of213Rn,215Ra and217Ra: Strongly Enhanced E3 Transitions in Odd-A N= 127 Isotones

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With the aim of searching for high-spin configurations involving the high-j neutron orbitals, excited states in 213Rn, 215Ra and 217Ra were populated in the bombardment of 208Pb with 13C ions. Gamma-ray singles, excitation functions and angular distributions, pulsed-beam-γ timing and γ-γ(t) coincidences were measured. Six isomeric levels were observed in 213Rn, three in 215Ra while none in 217Ra. The lowest-lying 15/2- states in all odd-A N = 127 isotones are de-excited by E3 transitions with a strength of about 23 W.u, suggesting that they are all coupled to the octupole phonon. In 217Ra no evidence for collective behavior is found despite its closeness to the actinide region. The low-lying states in the level scheme can be interpreted as arising from three-neutron configurations. The wave function of a Jπ = (37/2+) state in 213Rn is proposed to include about 30% admixture from the two-octupole configuration πh9/23f7/2 ⊗ vg9/2 ⊗ (3-)2 since the de-exciting E3 transition has a strength of about 40 W.u. This is the first indication of such an excitation in the lead region.