# Re-measurement of the ${}^{33}$S($\alpha$,p)${}^{36}$Cl cross section for Early solar system enrichment

## TL;DR

This study re-measured the ${}^{33}$S($ extalpha$,p)${}^{36}$Cl reaction cross section relevant to early solar system radionuclide production, finding lower values consistent with nuclear theory predictions, thus refining our understanding of solar system formation processes.

## Contribution

The paper provides new experimental cross section data for the ${}^{33}$S($ extalpha$,p)${}^{36}$Cl reaction, resolving discrepancies with previous measurements and supporting nuclear theory models.

## Key findings

- New measurements show lower cross sections than previous data.
- Results align with Hauser-Feshbach nuclear models.
- Implications for early solar system radionuclide production are clarified.

## Abstract

Short-lived radionuclides (SLRs) with half-lives less than 100 Myr are known to have existed around the time of the formation of the solar system around 4.5 billion years ago. Understanding the production sources for SLRs is important for improving our understanding of processes taking place just after solar system formation as well as their timescales. Early solar system models rely heavily on calculations from nuclear theory due to a lack of experimental data for the nuclear reactions taking place. In 2013, Bowers et al. measured ${}^{36}$Cl production cross sections via the ${}^{33}$S($\alpha$,p) reaction and reported cross sections that were systematically higher than predicted by Hauser-Feshbach codes. Soon after, a paper by Peter Mohr highlighted the challenges the new data would pose to current nuclear theory if verified. The ${}^{33}$S($\alpha$,p)${}^{36}$Cl reaction was re-measured at 5 energies between 0.78 MeV/A and 1.52 MeV/A, in the same range as measured by Bowers et al., and found systematically lower cross sections than originally reported, with the new results in good agreement with the Hauser-Feshbach code TALYS. Loss of Cl carrier in chemical extraction and errors in determination of reaction energy ranges are both possible explanations for artificially inflated cross sections measured in the previous work.