Radiative Capture of Protons byF19at a Bombarding Energy of 669 kev

Abstract

The ground-state transition from the 13.51-Mev state of ${\mathrm{Ne}}^{20}$ formed by bombarding fluorine with protons of 669 kev is anomalously weak. This is interesting because the 13.51-Mev state has a large reduced width for proton emission to the ground state of ${\mathrm{F}}^{19}$ and a large $M1\mathrm{}$ width for radiation to the first excited (1.63-Mev) state of ${\mathrm{Ne}}^{20}$. A simple explanation would be that the ground state of ${\mathrm{Ne}}^{20}$ is close to ${\left(2\mathrm{}{s}_{\frac{1}{2}}\right)}^4$. The ground-state radiation is sought and found using a 3-in.×3-in. NaI(Tl) crystal. The radiative width is approximately 1.0×${10}^{-2\mathrm{}}$ ev corresponding to ${\mathrm{}\left|M\right|\mathrm{}}^2\sim 2\times {10}^{-4\mathrm{}}$. The 13.51-Mev state is found also to radiate to the 4.97-Mev state with a width of approximately 0.24 ev. The 4.97-Mev state itself chiefly cascades via the first excited state: An upper limit on the relative strength of the ground-state transition is 0.07.