University of Jyväskylä

Dissertation: 27.10.2017 Spectroscopy and lifetime measurements of 166, 168Os (Stolze)

Start date: Oct 27, 2017 12:00 PM

End date: Oct 27, 2017 03:00 PM

Location: Ylistönrinne, FYS1

Sanna Stolze
M.Sc. Sanna Stolze defends her doctoral dissertation in Physics "Spectroscopy and lifetime measurements of 166,168Os". Opponent Doctor Marcus Scheck (University of the West of Scotland) and custos Ph.D. Tuomas Grahn (University of Jyväskylä).


Neutron-deficient osmium isotopes 166Os and 168Os have been studied with γ-ray spectroscopy and  lifetime measurements. The level scheme of 166Os 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 168Os, in 166Os the reduced transition probability is only few Weisskopf units, a value expected only at closed shells. In 168Os 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.

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Sanna Stolze
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