Spin-Orbit Coupling Energy inO17

A proportional counter filled with carbon dioxide was irradiated with monoenergetic fast neutrons produced by bombarding thin lithium targets with protons from an electrostatic generator. Angular distributions of neutrons scattered by oxygen were deduced from the energy spectrum of recoil oxygen ions for neutron energies from 392 kev to 1412 kev, determining the parities of three spin-$\frac{3}{2}$ levels in ${\mathrm{O}}^{17}$, 4.56, 5.08, and 5.39 Mev above the ground state. The 5.08-Mev state has even parity and appears to be the $D_{\frac{3}{2}}$ member of a $D_{\frac{5}{2}}-D_{\frac{3}{2}}$ doublet, where the $D_{\frac{3}{2}}$ level is then 5 Mev higher than the $D_{\frac{5}{2}}$ ground state of ${\mathrm{O}}^{17}$. The other two states have odd parity and lie more than 1.5 Mev above the lowest spin-½ odd-parity level. This may indicate a spin-orbit splitting of the order of 2 Mev or greater in the $P$ shell.