Narrow resonances in the continuum of the unbound nucleus $^{15}$F

TL;DR

This study investigates the unbound nucleus $^{15}$F using resonant scattering, confirming known narrow resonances and discovering new ones, with analysis supported by the Gamow shell model to understand their structure and decay modes.

Contribution

The paper reports the first identification of two new narrow resonances in $^{15}$F and demonstrates the effectiveness of the Gamow shell model in describing these unbound states.

Findings

Confirmed narrow 1/2$^{-}$ resonance near two-proton decay threshold.

Discovered two new narrow 5/2$^{-}$ and 3/2$^{-}$ resonances.

GSM analysis suggests continuum coupling influences resonance wave functions.

Abstract

The structure of the unbound $^{15}$F nucleus is investigated using the inverse kinematics resonant scattering of a radioactive $^{14}$O beam impinging on a CH$_2$ target. The analysis of $^{1}$H($^{14}$O,p)$^{14}$O and $^{1}$H($^{14}$O,2p)$^{13}$N reactions allowed the confirmation of the previously observed narrow $1/2^{-}$ resonance, near the two-proton decay threshold, and the identification of two new narrow 5/2$^{-}$ and 3/2$^{-}$ resonances. The newly observed levels decay by 1p emission to the ground of $^{14}$O, and by sequential 2p emission to the ground state (g.s.) of $^{13}$N via the $1^-$ resonance of $^{14}$O. Gamow shell model (GSM) analysis of the experimental data suggests that the wave functions of the 5/2$^{-}$ and 3/2$^{-}$ resonances may be collectivized by the continuum coupling to nearby 2p- and 1p- decay channels. The observed excitation function $^{1}$H($^{14}$O,p)$^{14}$O and resonance spectrum in $^{15}$F are well reproduced in the unified framework of the GSM.