New isomeric states in Fr and At |
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Authors: | G T Ewan E Hagberg B Jonson S Mattsson P Tidemand-Petersson |
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Institution: | The ISOLDE Collaboration, CERN, Geneva, Switzerland |
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Abstract: | Alpha spectroscopic data from the decay chain 218Fr → 214At → 210Bi have been obtained. Previously unobserved isomeric states were found in both 218Fr and 214At. The half-life of the ground state of 218Fr was measured to be 1.3+0.5 −0.4 ms. The half-life of the new isomeric state in 218Fr was determined to be 22.0±0.5 ms and its decay was found to be very complex with no fewer than 20 -groups varying in energy between 6837 keV and 7952 keV. Two long-lived states in 214At with half-lives of 558±10 ns and 760±15 ns, respectively, were found to be strongly populated in the decay of 218mFr. These two states are proposed to be a 1− ground state and a 9− isomeric state arising from the coupling between the unpaired h9/2 proton and g9/2 neutron. |
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Keywords: | Radioactivity |
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