Artistic illustration of three different deformations in the
atomic nucleus of lead-190. Credit Adrian Montes Plaza.
In fact, in many nuclei, different shapes can coexist within the same nucleus, with one of the richest regions for this phenomenon found in neutron-deficient lead nuclei.
A research team, led by scientists from the Universities of Liverpool (UK) and Jyväskylä (Finland), and the STFC Daresbury Laboratory (UK), has performed a series of studies on shape coexistence. These experiments focused on the 186,188,190Pb isotopes and were performed at the University of Jyväskylä. The research programme exploited the state-of-the-art SAGE spectrometer, constructed by the team with funding from STFC, the European Research Council and the Research Council of Finland.
The use of SAGE allowed the team to detect γ rays and conversion electrons that are emitted from the nuclei of interest at the production target. This simultaneous measurement was the first of its kind in lead isotopes and was key in disentangling the complex de-excitation patterns observed in the experiments. For the investigation of 190Pb, the team combined the SAGE results with those obtained in lifetime measurements and decay studies of metastable states. These complementary approaches provided a detailed picture of configuration mixing in this nucleus.
“In our studies, we were able to reassign some shapes previously associated with these nuclei. These findings challenge current theoretical models and provide crucial input for the development of more precise models" says Philippos Papadakis, from Daresbury Laboratory, who co-led this research programme.
Papers
Reassigning the shapes of the 0+ states in the 186Pb nucleus
Direct observation of E0 transitions in 188Pb through in-beam spectroscopy
Direct measurement of three different deformations near the ground state in an atomic nucleus (190Pb)
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