Determining concentrations of elements with different reaction channels in photon activation

In photon activation, same element may be activated by the bremsstrahlung beam through different nuclear reaction channels and produce different radioisotopes. These radioisotopes follow their own decay schemes and generate characteristic gamma rays. This phenomenon usually is an interference in spectra analysis, but it also offers a theoretical feasibility to determine the concentration of one element through different reaction channels. To realize this theoretical feasibility, we conducted series of photon activation experiments with sample and reference of known concentrations. Irradiation of the samples and the references were conducted with electronic LINAC with different photon converters at a peak energy around 30MeV. Several elements and their corresponding reaction channels were chosen to validate this procedure. Calculations of PAA were based on the internal monitor method. Our results have confirmed the advantages of current PAA reaction channel selection, and show that it might be beneficial to calculate the concentration of same elements with different reaction channels in some certain occasions. N-values, which indicate the relative intensity of reaction channels, were calculated and compared with those values generated from the photon activation at the Federal Institute for Materials Research and Testing in Germany (BAM). Results suggested that N values are impacted by several parameters of electron beam, and the design of electron-gamma converter may play a dominant role in determining N values.