Maier-Leibnitz Laboratoty in Munich (Germany)

Electric quadrupole matrix elements are key quantities in probing the collective structure of nuclei as they are a sensitive and direct measure of the quadrupole deformation. The precise determination of these matrix elements reveals the nuclear collectivity caused by the coherent motion of nucleons, and the associated nuclear wave functions. Modern nuclear
theory is providing refined calculations of electric quadrupole matrix elements and related properties in light nuclei. Of particular interest is the testing-ground nucleus 12C, as this is computationally accessible to most modern theoretical approaches, including ab initio and cluster calculations.

We carried out a Coulomb-excitation measurement of 12C ions at the Maier-Leibnitz Laboratoty in Munich (Germany) early May 2018. After looking for the right targets, we started the experiment running at some crazy 96000000000 (9.6 10^10 pps) 12C ions per second; which according to Paul Garrett can get even higher!  The toughest part will be to simulate with GEANT the Doppler-broadened line-shape for the 2+ peak in 12C.  These kind of Coulex measurements using a magnetic spectrometer are very scarce, with the last measurements attempted over 35 years ago at Chalk River (Canada) and the ANU (Australia). In my humble opinion – Gordon Ball allows it – our Coulex measurement at MLL is probably the best ever done with a magnetic spectrometer!  Cebo Malotana Ngwetsheni has what is probably the best data set ever to determine the shape (and other “little secrets”) of 12C.

Spectacular! It was an enormous pleasure to share this experiment with such a great team. Thanks Thomas Faestermann and Andy Bergmaier (MLL) for setting up the heavy ion detector and Q3D and the MLL Accelerator Group for delivering an excellent 12C beam. I’m on my way home, but Christina and Alison (UWC Postdocs 2021), Magda Zielińska, Vinzenz and Paul Garrett remain until early Wednesday morning to collect some more exciting data. Big thanks to everyone (don’t want to forget Kasia, who also is leaving today after lots of good work, and Mahmoud who saved me a couple of night shifts!