The reactions ${\mathrm{F}}^{19}(t, \alpha ){\mathrm{O}}^{18}$ and ${\mathrm{F}}^{19}(t, p){\mathrm{F}}^{21}$ have been studied, yielding the following results: the energy levels of ${\mathrm{O}}^{18}$ up to 6.8 Mev are 1.989, 3.504, 3.929, 5.007, 5.170, 5.311, 5.456, 6.190, and 6.328 Mev. The energy levels of ${\mathrm{F}}^{21}$ up to 2.14 Mev are 0.269, 1.087, 1.694, and 2.036 Mev. The mass defect of ${\mathrm{F}}^{21}$ is measured to be 6.195 Mev, giving a mass of 21.006653 atomic mass units. The yields and cross sections of the levels are studied. These results are compared with data obtained elsewhere and the isobaric systems of mass 18 and 21 are discussed.

• Received 29 August 1956

DOI:https://doi.org/10.1103/PhysRev.104.1683