# Improving the resolving power of Isochronous Mass Spectrometry by employing an in-ring mechanical slit

## TL;DR

This paper demonstrates that employing an in-ring mechanical slit in Isochronous Mass Spectrometry significantly enhances mass resolving power by reducing momentum spread, despite some ion loss, thus improving precision in exotic nuclei measurements.

## Contribution

The study introduces a mechanical slit system in IMS to improve mass resolution by controlling momentum acceptance and optimizing isochronous conditions.

## Key findings

- Mass resolving power improved to 5.2 x 10^5.
- Achieved higher precision in mass measurements of exotic nuclei.
- Ion loss increased by approximately 40%.

## Abstract

Isochronous Mass Spectrometry (IMS) in heavy-ion storage rings is an excellent experimental method for precision mass measurements of exotic nuclei. In the IMS, the storage ring is tuned in a special isochronous ion-optical mode. Thus, the mass-over-charge ratios of the stored ions are directly reflected by their respective revolution times in first order. However, the inevitable momentum spread of secondary ions increases the peak widths in the measured spectra and consequently limits the achieved mass precision. In order to achieve a higher mass resolving power, the ring aperture was reduced to 60 mm by applying a mechanical slit system at the dispersive straight section. The momentum acceptance was reduced as well as better isochronous conditions were achieved. The results showed a significant improvement of the mass resolving power reaching $5.2 \times 10^{5}$, though at the cost of about 40\% ion loss.