Experimental Range of Protons in Al

The ranges of protons of 1 to 6 Mev in Al have been determined experimentally. Combining these results with earlier experimental data, the range can be represented by the following analytic functions: for $1<E<\mathrm{}2.7\mathrm{}$ Mev, $R=3.837\mathrm{}{E}^{1.5874}$; for $2.7<E<\mathrm{}20\mathrm{}$ Mev, $R=\frac{2.837E^2}{(0.68+{log}_{10}E)}$, with $E$ in Mev and $R$ in mg/${\mathrm{cm}}^2$. A tentative comparison with the theory of stopping power was made. The neutron thresholds for proton bombardment of ${\mathrm{C}}^{13}$, ${\mathrm{F}}^{19}$, and ${\mathrm{Na}}^{23}$ were obtained as an incidental result.