# Beta-delayed-neutron studies of $^{135,136}$Sb and $^{140}$I performed with trapped ions

## TL;DR

This study measured beta-delayed-neutron emission probabilities and energy spectra for specific antimony and iodine isotopes using trapped ions, providing insights relevant to r-process nucleosynthesis.

## Contribution

It reports the first measurement of the beta-delayed-neutron energy spectrum for $^{136}$Sb and refines neutron emission data for $^{135}$Sb, $^{136}$Sb, and $^{140}$I.

## Key findings

- Beta-delayed-neutron branching ratios for $^{135}$Sb, $^{136}$Sb, and $^{140}$I were determined.
- First measurement of the beta-delayed-neutron energy spectrum for $^{136}$Sb.
- Results impact understanding of r-process nucleosynthesis around the A~130 peak.

## Abstract

Beta-delayed-neutron ($\beta$n) spectroscopy was performed using the Beta-decay Paul Trap and an array of radiation detectors. The $\beta$n branching ratios and energy spectra for $^{135,136}$Sb and $^{140}$I were obtained by measuring the time of flight of recoil ions emerging from the trapped ion cloud. These nuclei are located at the edge of an isotopic region identified as having $\beta$n branching ratios that impact the r-process abundance pattern around the A~130 peak. For $^{135,136}$Sb and $^{140}$I, $\beta$n branching ratios of 14.6(11)%, 17.6(28)%, and 7.6(28)% were determined, respectively. The $\beta$n energy spectra obtained for $^{135}$Sb and $^{140}$I are compared with results from direct neutron measurements, and the $\beta$n energy spectrum for $^{136}$Sb has been measured for the first time.