The most-probable ionization loss has been measured for relativistic electrons passing through thin absorbers of carbon, aluminum, and copper. Incident energies of 50 and 100 MeV were used. Target thicknesses ranged from 48 to 614 mg/${\mathrm{cm}}^2$ and encompass the range of thicknesses most frequently used in electron scattering experiments at these energies. The measured values of the most-probable ionization losses are in good agreement with the theoretical predictions of Sternheimer. The techniques for using values of the ionization loss to determine the target thickness in electron scattering experiments are presented.

[NUCLEAR REACTIONS Nat. C, Al, $\mathrm{Cu} (e,e^{\prime })$, $E=50,100\mathrm{}$ MeV; measured most-probable energy loss for electrons.]

• Received 15 October 1973

DOI:https://doi.org/10.1103/PhysRevC.9.1418