Spectroscopy and lifetime measurements of 166 168Os
Spectroscopy and lifetime measurements of 166 168Os
Neutron-deficient osmium isotopes <sup>166</sup>Os and <sup>168</sup>Os have been studied with γ-ray spectroscopy and lifetime measurements. The level scheme of <sup>166</sup>Os has been expanded with several new structures including second the 8+ and 10+ states. These states confirm the change in the structure of the yrast band between the 6+ and 8+ states. Lifetimes of the low-lying excited states have been measured in an RDDS measurement. The results reveal a sudden decrease in the collectivity when moving towards the neutron shell closure. While the 2+ → 0+ transition is still collective in <sup>168</sup>Os, in <sup>166</sup>Os the reduced transition probability is only few Weisskopf units, a value expected only at closed shells. In <sup>168</sup>Os the 4+ → 2+ transition is remarkably less collective than the 2+ → 0+ transition. While nuclear models predict a decrease in collectivity, no modern calculations can explain the measured transition probabilities.
Sarja | Jyväskylän yliopisto. Fysiikan laitos. Research report |
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ISBN |
978-951-39-7208-0 |
ISSN |
0075-465X |