The new accelerator facility FAIR is under construction at GSI. Learn more.


GSI is member of


Funded by




20.06.2013 | Uncovering forces in calcium nuclei

Foto: Klaus Blaum

ISOLTRAP experiment


GSI is part of experiments to uncover the binding forces in calcium nuclei. The results were now published in the journal "Nature". To conduct the experiment the researchers used the ISOLTRAP setup at the european research centre CERN in Switzerland. GSI is part of the ISOLTRAP collaboration and among other things developed essential parts of the control and data analysis system of the setup. The same system is also used at GSI experiments like the ion trap SHIPTRAP or the PHELIX laser. Parts of the setup were also contributions from GSI, GSI scientists and doctoral candidates were involved in the experiments.

Recently the measurement of the isotopes calcium-53 and calcium-54 was successful. They were produced with aid of an accelerator and afterwards weighed in the ISOLTRAP setup. Calcium has a closed proton shell and is therefore suited for studies of the binding forces inside the nucleus. In different calcium isotopes the development from stable elements in the valley of stability up to the border of the nuclear chart can be observed. The two measured isotopes have a high number of neutrons in the nucleus, thus being very close to the border. The measurements show a new shell closure at a neutron number of 32 as it was already predicted in theoretical calculations performed by researchers from the Technical University of Darmstadt, aided by the ExtreMe Matter Institute EMMI at GSI.

Involved in the experiments were GSI, CERN, the Max-Planck-Institute for Nuclear Physics in Heidelberg and the universities of Dresden, Greifswald, Istanbul (Turkey), Leuven (Belgium) and Orsay (France).

Scientific publication in "Nature"

Press release of the Technical University of Darmstadt 

Press release of CERN


ISOLTRAP experiment
Foto: Klaus Blaum