Spatial selection of ions separated in a multi-reflection time-of-flight mass analyzer

Multi-reflection time-of-flight mass analyzers (MR TOF MAs) have become widely used in nuclear physics research due to their combination of high mass resolving power, mass measurement accuracy, and high analysis speed. For MR TOF MA of super-high resolving power approaching 1 000 000, it is advantageous to keep the time width of ion packets at the detector possibly narrow (2–5 ns) in order to provide for reasonably small flight time below 10 ms and allow experiments with short-lived nuclei. These devices can also be used as mass separators, with ion selection typically performed using electric shutters, allowing for a time resolution of around 20 ns. Thus, the mass resolving power of ion selection can be up to one order of magnitude lower than that of MR TOF MAs. In the paper, a novel method is proposed that significantly improves the resolving power of the selection of ions separated by flight time in an MR TOF MA. The method is based on converting the difference in flight times between ions into differences in their energies using an electric energy buncher. Subsequently, ions of different masses with different flight times are spatially separated in an electrostatic analyzer, and can be selected using a slit aperture. Numerical simulations demonstrate that the mass resolving power of the resulting lateral spatial separation of ions can be practically equal to the resolving power of longitudinal separation in MR TOF MAs. • New method of high-resolution selection of ions separated in TOF mass analyzers • Conversion of a longitudinal mass separation of ions into a lateral spatial mass separation • Energy bunching converts the time difference at the exit of a TOF analyzer into an energy difference • Mass resolving power of ion selection is similar to the resolving power of the TOF analyzer