First Determination of Level Structure of an $sd$-Shell Hypernucleus, ${}_{\mathrm{\Lambda }}^{19}\mathrm{F}$

Abstract

We report on the first observation of $\gamma$ rays emitted from an $sd$-shell hypernucleus, ${}_{\mathrm{\Lambda }}^{19}\mathrm{F}$. The energy spacing between the ground state doublet, $1/2^{+}$ and $3/2^{+}$ states, of ${}_{\mathrm{\Lambda }}^{19}\mathrm{F}$ is determined to be $315.5\pm 0.4(\mathrm{stat}{)}_{-0.5}^{+0.6}(\mathrm{syst})\mathrm{keV}$ by measuring the $\gamma$-ray energy from the $M1(3/2^{+}\to 1/2^{+})$ transition. In addition, three $\gamma$-ray peaks were observed and assigned as $E2(5/2^{+}\to 1/2^{+})$, $E1(1/2^{-}\to 1/2^{+})$, and $E1(1/2^{-}\to 3/2^{+})$ transitions. The excitation energies of the $5/2^{+}$ and $1/2^{-}$ states are determined to be $895.2\pm 0.3(\mathrm{stat})\pm 0.5(\mathrm{syst})\mathrm{keV}$ and $1265.6\pm 1.2(\mathrm{stat}{)}_{-0.5}^{+0.7}(\mathrm{syst})\mathrm{keV}$, respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing $s$- and $p$-shell hypernuclear data.

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• Big-Bang Nucleosynthesis
• Strangeness in nuclear physics
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• High Resolution Spectroscopic Study of ${}_{\Lambda }^{10}$Be
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Cited by in corpus (3)

• Towards the understanding of the genuine three-body interaction for p$-$p$-$p and p$-$p$-\Lambda$
• The interplay of single-particle and collective motions in the low-lying states of ${}_{\Lambda }^{21}$Ne with quadrupole-octupole correlations
• Experimental techniques and performance of $\Lambda$-hypernuclear spectroscopy with the $(e,e^{\prime }{K}^{+})$ reaction