N17, A Delayed Neutron Emitter

The decay scheme of a 4.2-second neutron emitter has been investigated in detail. Chemical and physical evidence shows that it is ${\mathrm{N}}^{17}$, which emits beta-rays to a broad excited state of ${\mathrm{O}}^{17}$, which then breaks up into a neutron plus ${\mathrm{O}}^{16}$. The energy spectrum of the neutrons is determined by measuring the energies of the ${\mathrm{O}}^{16}$ recoils in a proportional counter. The neutrons have a most probable energy of 0.9 Mev, a "half-width" of less than 0.5 Mev, and an upper limit of about 2 Mev. $\beta$-recoil coincidences are observed, as predicted by the Bohr-Wheeler theory, and the $\beta$-ray energy is measured by absorption. The beta-rays in coincidence with neutrons have an upper limit of 3.7±0.2 Mev. Beta-rays directly to the ground state of ${\mathrm{O}}^{17}$ are not observed because of high background effects, but should have an energy of 8.7 Mev. Some evidence is presented to show that energy is conserved in the $\beta -n$ transition through the broad excited state in ${\mathrm{O}}^{17}$.