Half-Lives of ${\mathrm{Be}}^{11}$, ${\mathrm{C}}^{15}$, ${\mathrm{N}}^{16}$, ${\mathrm{O}}^{19}$, and ${\mathrm{Al}}^{28}$

The half-lives of several radioactivities induced by Van de Graaff bombardment have been measured using plastic and NaI(Tl) scintillation detectors, together with a time-channel analyzer controlled by a quartz-crystal clock. The half-lives obtained are as follows: ${\mathrm{Be}}^{11}$, 13.81 ± 0.08 sec; ${\mathrm{C}}^{15}$, 2.46 ± 0.01 sec; ${\mathrm{N}}^{16}$, 7.13 ± 0.04 sec; ${\mathrm{O}}^{19}$, 27.1 ± 0.1 sec; and ${\mathrm{Al}}^{28}$, 2.252 ± 0.006 min.