Search for $2p$ decay of the first excited state of $^{17}$Ne

TL;DR

This study investigates the two-proton decay of the first excited state of $^{17}$Ne, setting new upper limits on its decay width and introducing a novel method to improve experimental resolution for states with very small particle-to-gamma width ratios.

Contribution

The paper introduces a new 'combined mass' method to enhance resolution in nuclear decay experiments, particularly for states with tiny particle-to-gamma width ratios.

Findings

Established a new upper limit for the two-proton decay width ratio of $^{17}$Ne's excited state.

Demonstrated the effectiveness of the 'combined mass' method in improving experimental resolution.

Highlighted the method's relevance for astrophysical nuclear states with small particle widths.

Abstract

Two-proton decay of the $^{17}$Ne low-lying states populated in the $^1$H($^{18}$Ne,$d$)$^{17}$Ne transfer reaction was studied. The two-proton width $\Gamma_{2p}$ of the $^{17}$Ne first excited $3/2^-$ state at $E^*=1.288$ MeV is of importance for the two-proton radioactivity theory and nuclear-astrophysics applications. A dedicated search for the two-proton emission of this state was performed leading to the new upper limit obtained for the width ratio $\Gamma_{2p}/\Gamma_{\gamma} < 1.6(3) \times 10^{-4}$. A novel, "combined mass" method is suggested and tested capable to improve the resolution of the experiment which is a prime significance for the study of nuclear states with extremely small particle-to-gamma width ratios $\Gamma_{\mathrm{part}}/\Gamma_{\gamma}$. The condition $\Gamma_{\mathrm{part}} \ll \Gamma_{\gamma}$ is quite common for the states of astrophysical interest which makes the proposed approach promising in this field.