Single-particle and collective excitations in the transitional nucleus Os-166

• The mean lifetimes of the lowest energy 2(+), 8(+) and 9(-) states in Os-166 have been measured using the recoil distance Doppler-shift method in conjunction with a selective recoil-decay tagging technique. These measurements extend studies into the most neutron-deficient mass region accessible to current experimental methods. The B(E2; 2(+) -> 0(+)) = 7(2) W.u. extracted from these measurements is markedly lower than those observed in the heavier even-mass Os isotopes. The 8(+) and 9(-) states yield reduced transition probabilities that are consistent with single-particle transitions. While these values may indicate a departure from collective structure, the level scheme and the underlying nuclear configurations can also be interpreted in terms of a simple collective picture. This contrasting behaviour suggests an intriguing dichotomy in the description of heavy transitional nuclei.

Ämnesord

NATURVETENSKAP  -- Fysik -- Subatomär fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Subatomic Physics (hsv//eng)

Nyckelord

mean lifetimes

RDDS measurements

gamma-ray spectroscopy

collectivity

single-particle states

electromagnetic transitions

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