"Recent progress in two-proton radioactivity study: the discovery of 67Kr" Thomas Goigoux

vendredi 25 mai 2018, 10:45 → 12:45 Europe/Paris

Pistache (Batiment 27)

The decay modes of proton-rich nuclei are dominated by β+ radioactivity. For these nuclei, the one and two proton
separation energies are positive, thus the emission of one or two protons from ground state is energetically
prohibited. Beyond the proton drip line, the proton separation energy becomes negative, allowing the one- and
two-proton emission to compete with β+ decay.
Observed for even proton number nuclei because of the pairing effect, two-proton radioactivity reveals as a
tool to study the nuclear structure near the drip line. This decay was discovered in 2002 with the observation
of 45Fe at GANIL and GSI. Then followed the observation of the medium-mass emitters 48Ni and 54Zn.
These observations were completed with experiments using time projection chambers, allowing to estimate
the angular and energy correlations and explore nuclear structure. In the higher mass domain, the candidates
according to local-mass models are 59Ge, 63Se and 67Kr.
In a 78Kr fragmentation experiment at 345 MeV/A performed at the BigRIPS facility in 2015, the two-proton
radioactivity of 67Kr was unambiguously identified. This discovery opens the way to a more detailed study
by the use of a time projection chamber.