Nuclear structure studies of ${}^{24}\mathrm{F}$

The structure of the ${}^{24}\mathrm{F}$ nucleus has been studied at GANIL using the $\beta$ decay of ${}^{24}\mathrm{O}$ and the in-beam $\gamma$-ray spectroscopy from the fragmentation of ${}^{27,28}\mathrm{Na},{}^{25,26}\mathrm{Ne},$ and ${}^{29,30}\mathrm{Mg}$ nuclei. Combining these complementary experimental techniques, the level scheme of ${}^{24}\mathrm{F}$ has been constructed up to $3.6\text{MeV}$ by means of particle-$\gamma$ and particle-$\gamma \gamma$ coincidence relations. Experimental results are compared to shell-model calculations using the standard USDA and USDB interactions as well as ab initio valence-space Hamiltonians calculated from the in-medium similarity renormalization group based on chiral two- and three-nucleon forces. Both methods reproduce the measured level spacings well, and this close agreement allows unidentified spins and parities to be consistently assigned.

Figure 1

Energy loss versus time-of-flight identification matrix. The relative yields of the implanted ions are shown by different shades.

Figure 2

(a) $\beta$-gated $\gamma$-ray spectrum following the implantation of ${}^{24}\mathrm{O}$ nuclei obtained in the 0–250 ms range. (b) $\gamma \gamma$-coincidence spectrum gated by the 1309 keV $\gamma$ ray.

Figure 3

Background-subtracted summed time distribution gated on the 521, 1309, and 1830 keV $\gamma$ rays following the implantation of ${}^{24}\mathrm{O}$ nuclei. The fit with a single exponential decay curve yields $T_{1/2}=80\left(5\right)$ ms.

Figure 4

Singles $\gamma$-ray spectrum obtained in coincidence with the ${}^{24}\mathrm{F}$ nuclei produced in the in-beam $\gamma$-ray spectroscopy experiment. The inset presents a zoom on the high-energy part of the spectrum. The lines show the result of the fit with line shapes obtained from geant simulation.

Figure 5

$\gamma \gamma$-coincidence spectra gated by the 1309 and 3118 keV transitions measured in the in-beam data set.

Figure 6

Experimental level scheme of ${}^{24}\mathrm{F}$ obtained in the in-beam and $\beta$-decay data set compared to shell-model calculations performed with the USDA and USDB interactions as well as ab initio valence-space Hamiltonians calculated from the in-medium similarity renormalization group.