# A Novel Method for the Measurement of Half-Lives and Decay Branching Ratios of Exotic Nuclei

## TL;DR

This paper introduces a new method combining a cryogenic stopping cell and a multiple-reflection time-of-flight mass spectrometer to measure half-lives, decay branching ratios, and masses of exotic nuclei simultaneously, demonstrating high precision and feasibility.

## Contribution

The novel approach integrates a stopping cell as an ion trap with MR-TOF-MS for comprehensive decay measurements, including the first direct mass measurements of specific nuclear isomers.

## Key findings

- Successfully measured half-lives and branching ratios consistent with literature
- First direct mass measurements of $^{119g}$Sb and $^{119m2}$Sb states
- Demonstrated the method's high cleanliness and minimal decay losses

## Abstract

A novel method for simultaneous measurement of masses, Q-values, isomer excitation energies, half-lives and decay branching ratios of exotic nuclei has been demonstrated. The method includes first use of a stopping cell as an ion trap, combining containment of precursors and decay-recoils for variable durations in a cryogenic stopping cell (CSC), and afterwards the identification and counting of them by a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). Feasibility has been established by recording the decay and growth of $^{216}$Po and $^{212}$Pb (alpha decay) and of $^{119m2}$Sb (t$_{1/2}$ = 850$\pm$90 ms) and $^{119g}$Sb (isomer transition), obtaining half-lives and branching ratios consistent with literature values. Hardly any non-nuclear-decay losses have been observed in the CSC for up to $\sim$10 seconds, which exhibits its extraordinary cleanliness. For $^{119}$Sb, this is the first direct measurement of the ground and second isomeric state masses, resolving the discrepancies in previous excitation energy data. These results pave the way for the measurement of branching ratios of exotic nuclei with multiple decay channels.