# New $\gamma$-ray Transitions Observed in $^{19}$Ne with Implications for the $^{15}$O($\alpha$,$\gamma$)$^{19}$Ne Reaction Rate

## TL;DR

This study observed new gamma-ray transitions in $^{19}$Ne, leading to revised spin-parity assignments for key states, which impacts the reaction rate calculations for astrophysical processes like x-ray bursts.

## Contribution

The paper provides new gamma-ray transition data that revise the spin-parity assignments of specific states in $^{19}$Ne, improving understanding of the $^{15}$O($eta$,$
abla$)$^{19}$Ne reaction.

## Key findings

- Revised spin-parity assignments for 4.14- and 4.20-MeV states in $^{19}$Ne.
- Strong evidence supporting $J^ ext{pi}$ of 7/2$^-$ and 9/2$^-$ for these states.
- Implications for more accurate reaction rate calculations in astrophysical models.

## Abstract

The $^{15}$O($\alpha$,$\gamma$)$^{19}$Ne reaction is responsible for breakout from the hot CNO cycle in Type I x-ray bursts. Understanding the properties of resonances between $E_x = 4$ and 5 MeV in $^{19}$Ne is crucial in the calculation of this reaction rate. The spins and parities of these states are well known, with the exception of the 4.14- and 4.20-MeV states, which have adopted spin-parities of 9/2$^-$ and 7/2$^-$, respectively. Gamma-ray transitions from these states were studied using triton-$\gamma$-$\gamma$ coincidences from the $^{19}$F($^{3}$He,$t\gamma$)$^{19}$Ne reaction measured with GODDESS (Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies) at Argonne National Laboratory. The observed transitions from the 4.14- and 4.20-MeV states provide strong evidence that the $J^\pi$ values are actually 7/2$^-$ and 9/2$^-$, respectively. These assignments are consistent with the values in the $^{19}$F mirror nucleus and in contrast to previously accepted assignments.