One-phonon octupole vibrational states in 211At, 212Rn, 213Fr and 214Ra with N = 126

Abstract

Excited high spin states in 211At, 212Rn, 213Fr and 214Ra with N = 126 are reorganized and interpreted in terms of the stretched weak coupling of an octupole 3− phonon. Nearly identical sequences of levels with ΔI = 3 and the parity change are found, for the first time, up to 25− for 20 states of 214Ra, up to 35− for 36 states of 212Rn and up to 53/2+ for 16 states of 213Fr. The stretched weak coupling of an octupole phonon is extended up to the highest excitation energy of 11355 keV for 212Rn which has the largest experimental B(E3) value of 44.1(88) W.u. for the 11− → 82+ transition. The stretched weak coupling of an octupole 3− phonon needs to be considered when single particle configurations are assigned to high spin states. Average octupole excitation energies of 657(51) keV for 211At, 1101(28) keV for 212Rn, 667(25) keV for 213Fr, and 709(25) keV for 214Ra are obtained. The calculated level enegies are in a good agreement with the experimental level energies within the error limit of 4.3%.