Design and characterization of a Cryogenic Stopping Cell for radioactive ions

PhD ceremony: Ms. M. Ranjan, 14.30 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Design and characterization of a Cryogenic Stopping Cell for radioactive ions

Promotor(s): prof. N. Kalantar-Nayestanaki

Faculty: Mathematics and Natural Sciences

In-flight radioactive ion beam facilities deliver radioactive ions at very high energies. Studies requiring low-energy ions, e.g. using laser techniques and atom and ion traps, thus need the transformation of these high-energy ions into a low-energy ion beam. For this purpose, a so-called “Cryogenic Stopping Cell” was developed at KVI, University of Groningen. In this device, energetic radioactive ions are stopped in a noble gas (helium in the present work) and transported towards the exit side using a static electric field. At the exit side, a state-of-the-art radiofrequency carpet guides the ions to a small exit-hole from which they are extracted as a low-energy beam. Cryogenic operation ensures the required stopping gas purity.

The Cryogenic Stopping Cell is designed for use at the Fragment Separator at the GSI Helmholtz Centre for Heavy Ion Research and the Super-Fragment Separator to be installed at the Facility for Antiproton and Ion Research (FAIR) under construction at GSI (Darmstadt, Germany).

The Cryogenic Stopping Cell is the first of its kind. It was successfully validated by experiments using radioactive sources and high-energy radioactive ions from the Fragment Separator facility. The stopping cell was operated at a density almost two times higher than ever reached before. The technology used will allow to use even higher densities. The results represent a milestone in the stopping-cell development around the world.