Frankfurt 2014 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 45: Instrumentierung

HK 45.5: Vortrag

Donnerstag, 20. März 2014, 15:15–15:30, HZ 10

Performance of the Cryogenic Stopping Cell for the LEB at the FRS Ion Catcher — •Moritz Pascal Reiter for the FRS Ion Catcher collaboration — II.Physikalsiche Institut JLU Giessen

At the FRS Ion Catcher, projectile and fission fragments are produced at relativistic energies, separated in-flight, range-focused, slowed-down and thermalized in a cryogenic stopping cell (CSC) to kinetic energies to a few eV. A multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) is used to perform direct mass measurements and to remove isobaric contaminants. The isobarically clean beam may be delivered to further experiments, for example mass-selected decay spectroscopy. The FRS Ion Catcher serves as a test bench for the Low-Energy-Branch of the Super-FRS at FAIR, where the CSC and the MR-TOF-MS will be key devices for experiments with stopped projectile and fission fragments. The CSC has been commissioned with ²³⁸U projectile fragments produced at 1000 MeV/u. The spatial isotopic separation in-flight was performed with the FRS applying a monoenergetic degrader. For the first time, a stopping cell was operated with exotic nuclei at cryogenic temperatures (70 to 100 K). An overall efficiency of up to 15 %, a combined ion survival and extraction efficiency of about 50 %, and short extraction times of 24 ms were achieved for heavy α-decaying uranium fragments. Mass spectrometry with a multiple-refection time-of-fight mass spectrometer has demonstrated the excellent cleanliness of the CSC. In this presentation advantages of the cryogenic operation for the cleanliness as well as the behavior of the CSC during the online experiments will be discussed.