Removal of molecular contamination in low-energy RIBs by the isolation-dissociation-isolation method

[摘要] Experiments with low-energy rare ion beams often suffer from a large amount of molecular contaminant ions. We present the simple isolation-dissociation-isolation method to suppress this kind of contamination. The method can be applied to almost all types of low-energy beamlines. In a first step, a coarse isolation of the mass-to-charge ratio of interest is performed, e.g. by a dipole magnet. In a second step, the ions are dissociated. The last step is again a coarse isolation of the mass-to-charge ratio around the ion of interest. The method was tested at the FRS Ion Catcher at GSI with a radioactive ion source installed inside the cryogenic stopping cell as well as with relativistic ions delivered by the synchrotron SIS-18 and stopped in the cryogenic stopping cell. The isolation and dissociation, here collision-induced dissociation, have been implemented in a gas-filled RFQ beam-line. A reduction of molecular contamination by more than 4 orders of magnitude was achieved.

[发布日期] 2020-01-15

[效力级别]  Proceedings Paper

[关键词] Collision-induced dissociation;Low-energy RIB;RF-quadrupole;Beam purification;Molecular contamination