Energy of Beta-Radiation fromS35andC14

Aluminum-absorption curves have been obtained for ${\mathrm{C}}^{14}$ and ${\mathrm{S}}^{35}$. The ranges in aluminum, measured as suggested by Feather, are 27.9±0.3 mg/${\mathrm{cm}}^2$ for ${\mathrm{C}}^{14}$ and 31.4±0.5 mg/${\mathrm{cm}}^2$ for ${\mathrm{S}}^{35}$. The energies deduced from these ranges are 154±4 kev for ${\mathrm{C}}^{14}$ and 167±4 kev for ${\mathrm{S}}^{35}$. Measurements have also been made of the self-absorption of Ba${\mathrm{C}}^{14}$ ${\mathrm{O}}_3$, yielding an absorption coefficient $\alpha =0.29\mathrm{}$.