Energy Levels in ${\mathrm{C}}^{12}$ from ${\mathrm{Be}}^9(\alpha ,n){\mathrm{C}}^{12}$

A thin polonium source and thin beryllium target have been used to investigate energy states in ${\mathrm{C}}^{12}$. The neutron spectrum was determined from proton tracks in Eastman NTA emulsions. By investigating the neutrons emitted in the forward and backward directions, neutrons associated with the transition to the ground state of ${\mathrm{C}}^{12}$ were detected, and excited levels in ${\mathrm{C}}^{12}$ were identified at 4.2 and 7.5 Mev above the ground state.