Areal-density measurement of 12C and 13C foils and layers using the (3He,p) nuclear reaction

Abstract A method of accurately measuring the areal densities of isotopic stable carbon layers and foils is presented. The method utilizes the ( 3 He,p) nuclear reaction at incident energies near 3.5 MeV. A self-supporting foil whose areal density is accurately known from a Rutherford backscattering measurement is used as a standard. The particular advantage of the method presented here is that it can be used on 12 C or 13 C layers deposited on massive substrates. Accuracies of ±5% are obtained. Preparation and characterisation of 13 C layers with areal densities near 20 μg/cm 2 is described. The application of this method to 12 C foils and layers is outlined.