Elsevier

Physics Letters B

Volume 215, Issue 2, 15 December 1988, Pages 242-246
Physics Letters B

Enhanced E1 deexcitations in 218Ra and the evolution of reflection asymmetry at moderate spins

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Abstract

The kinematically reversed reaction 13C(208Pb, 3n)218Ra was used at 5.31 MeV/u to measure lifetimes of states with spins up to 15 in 218Ra, employing the Doppler shift recoil distance method. The higher spin states in 218Ra exhibit enhanced E1 decays with B(E1)≈6×10−3 W.u.. These enhanced B(E1)'s suggest a new form of collective dipole deexcitation arising from a reflection asymmetric intrinsic state. The measured B(E1)'s increase with spin between the Iπ=6+, 7 and 8+ states. It is suggested that, at higher spins, reflection asymmetry is enhanced as a consequence of octupole deformations stabilized by rotations or equivalently because of larger wavefunction admixture from cluster states.

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Supported in part by US DOE Contract No. DE-AC02-76ER03074 and by the West German Bundesminister für Wissenschaft und Technologie (Förderungskennzeichen 06 ML 177II).

1

Permanent address: AT&T, Rm. C64-A201, 131 Morristown Road, Basking Ridge, NJ 07920, USA.

2

Permanent address: Université Algèr, Algiers, Algeria.