A study has been made in the energy range up to 800 kev of ${\mathrm{He}}^3$ capture on ${\mathrm{He}}^3$ and the reactions that accompany this capture. The proton energy spectrum was found to confirm an earlier observation that the capture is followed by two modes of disintegration, viz., into two protons and an $\alpha$ particle, and into a proton and ${\mathrm{Li}}^5$. Improved resolution and statistics give no evidence of well-defined groups of protons of energy less than the ${\mathrm{Li}}^5$ ground-state group. The total reaction cross section was observed to rise monotonically in a manner suggesting partial waves of $l$ greater than one. At 200 kev the cross section is at least 2.5 microbarns, substantiating the fact that the capture of ${\mathrm{He}}^3$ on ${\mathrm{He}}^3$ is the dominant reaction terminating the $p-p$ cycle for stellar production of energy.

• Received 21 December 1953

DOI:https://doi.org/10.1103/PhysRev.94.87