Method for the Determination of the End-Point Energy of Beta Emitters

It was found that the absorption of beta spectra in materials of high atomic number is exponential. The absorption coefficients in gold are inversely proportional to the $\frac{3}{2}$ power of the end-point energy of the spectrum. This experimental law holds with 2 percent accuracy in the energy interval from 0.3 Mev to 2.2 Mev and in the intensity domain from ½ to $\frac{1}{100}$ of the original intensity, if a detector with less than 2 percent relative opening is used. The end-point energy of beta emitters can, therefore, be determined by measuring only two points on a gold absorption curve and is expressed by the equation: $E=9\mathrm{}{\mu }^{-\frac{2}{3}}+0.015\mathrm{}$ with 2 percent accuracy from 0.17 Mev to 2.2 Mev; where $E$ is the end-point energy in Mev and $\mu$ the absorption coefficient in ${\mathrm{cm}}^2$/g.