Collective behavior in Rb-78

Kaye, R.A.; Riley, L.A.; Solomon, G.Z.; Tabor, S.L.; Semmes, P.

doi:10.1103/PhysRevC.58.3228

Collective behavior in Rb-78

Dec, 1998

8 pages

Published in:

Phys.Rev.C 58 (1998) 3228-3236

DOI:

10.1103/PhysRevC.58.3228

View in:

Nuclear Science References

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Abstract: (APS)

Mean lifetimes of 10 states in 78Rb have been measured using the recoil-distance method. The γ-ray spectra of the recoils produced following the 58Ni(23Na,2pn)78Rb reaction at 70 MeV were observed in prompt coincidence using the FSU plunger in the Pitt-FSU detector array. Different decay curves in different coincidence gates provide additional confirmation for the 153 keV doublet in the level scheme. The alternating pattern of B(M1) strengths observed previously in the yrast band was seen to continue down to lower spins but with an attenuated magnitude, in agreement with neighboring odd-odd nuclei 74Br and 82Y. A slight reduction in collectivity with decreasing spin was inferred in the lowest positive- and negative-parity bands based on the gradual decrease in the B(E2) strengths. Particle-rotor model calculations predict strong alternations in both the signature splitting and B(M1) strength pattern in the positive-parity yrast band, in qualitative agreement with the experimental results.