K=8- isomer of 254No : one small step for Super Heavy Element physics

by Alexandre Brizard (3^rd year PhD student)

In the quest towards the production of superheavy elements and the explanation of their stability and structure, the question of the configuration of the K=8- isomer of nobelium has been a source of debate since its discovery in 1973. Theory and decay spectroscopy measurements have tried to explain this nucleus, its structure giving relevant input for theory.

Due to a large difference in g factors for the different possible configurations, a new technique of laser spectroscopy was finally able to provide clear data on the topic in a beamtime earlier this year. The JetRIS setup at GSI, Germany, is a In Gas Jet Laser Ionisation Spectroscopy setup developed in collaboration with other labs among which GANIL. Its fast extraction of the ions, combined with the high resolution that the ionisation in a gas jet provides, played a key role in the success of this measurement.

The preliminary results of the beamtime will be discussed as well as the technical development of the setup.