IRREGULARITIES IN SIDE-FEEDING PATTERNS, ENERGIES, AND MULTIPOLARITIES IN THE ER-154 YRAST CASCADE TO SPIN-36

States of Er154 were studied by means of the (O16,4n) and (Ni64,4n) reactions. Beginning with a 40-nsec isomeric state =(10-,11-)], an intensely populated unusual cascade of J=2 and J=1 transitions was established up to spin (35,36) and 12.5 MeV excitation. On an E vs I(I+1) plot the yrast levels form a series of straight-line segments with side feeding occurring primarily at the ends of segments. A second cascade of even-spin, even-parity levels from the ground state to J=18+ (quasi-ground-state band) does not exhibit these properties. © 1979 The American Physical Society.