Formation ofHe6by 14-Mev Neutron Bombardment of Li and Be

Formation of ${\mathrm{He}}^6$ by bombardment of ${\mathrm{Li}}^6$, ${\mathrm{Li}}^7$, and ${\mathrm{Be}}^9$ with 14-Mev neutrons has been observed. The ${\mathrm{He}}^6$ was identified by its known half-life and the decay rate observed on a ten-channel time-delay analyzer. Beta-rays from the ${\mathrm{He}}^6$ were detected by means of a thin-walled proportional counter, and the over-all counting efficiency was determined by using the ${\mathrm{Cu}}^{63}(n, 2n){\mathrm{Cu}}^{62}$ reaction. Cross sections determined for the ${\mathrm{Li}}^6(n, p)$, ${\mathrm{Li}}^7(n, d)$, and ${\mathrm{Be}}^9(n, \alpha )$ reactions were 6.7±0.8, 9.8±1.1, and 10±1 millibarns, respectively. The half-life of ${\mathrm{He}}^6$ was found to be 0.83±0.03 second.