Range-Energy Relations for Electrons and the Determination of Beta-Ray End-Point Energies by Absorption

It is shown that for aluminum absorbers, a single range-energy equation R=412 {E₀}^1. 265-0. 0954ln{E₀} (mg/cm^2) will fit the most reliable published values of practical ranges of monoenergetic electrons and the maximum ranges of nuclear beta-rays in the energy region 0. 01~2. 5 Mev. It is shown that the curve (dE₀dR) is nearly parallel to the theoretical curve for the rate of energy loss by ionization in the region between 0. 01 and 20 Mev and is about 25 percent larger. The reason for this discrepancy is not known. All the methods commonly used to determine the ranges of beta-rays from absorption curves are discussed and a new method developed by the authors is presented.