The energies of alpha particles emitted by ${\mathrm{Po}}^{210}$ and ${\mathrm{Po}}^{214}$ were compared with a broad-range spectrograph. Techniques were the same as those used in a recent comparison of the ${\mathrm{Po}}^{210}$ alpha-particle energy with the ${\mathrm{Li}}^7(p, n){\mathrm{Be}}^7$ reaction threshold energy. The result agrees with other measurements, and, thus, the discrepancy between the ${\mathrm{Po}}^{210}$ alpha-particle energy measured against the Briggs value for ${\mathrm{Po}}^{214}$ and the ${\mathrm{Po}}^{210}$ alpha-particle energy measured absolutely or against the ${\mathrm{Li}}^7(p, n){\mathrm{Be}}^7$ threshold remains. If Rytz's recent absolute value for the ${\mathrm{Po}}^{214}$ energy is used the discrepancy disappears. A summary of all measurements shows that the energy of alpha particles from ${\mathrm{Po}}^{210}$ is very close to 5.3045 Mev.

• Received 18 December 1961

DOI:https://doi.org/10.1103/PhysRev.126.1139