Determination of Tritium-Helium-3 differential cross-section in the energy range between 0.6 MeV and 3.3 MeV for tritium depth profiling in solids

The differential cross-section for the He-3+H-3 nuclear reaction was measured in a thin tritiated PdTi film that was deposited on a Si wafer. The sample was loaded with H-3(2) gas at a temperature of 300 degrees C and at a pressure of 1.8 bar. The total activity of the sample, measured by the liquid scintillation technique, was found to be 395 MBq. Two peaks were observed in the spectrum of the thick Si detector, corresponding to the H-3(He-3,d)He-4 and H-3(He-3,p)He-5 reaction channels. The differential cross-section was determined for the energy range of the He-3 beam from 0.6 to 3.4 MeV, at three scattering angles of 125, 135 and 155 degrees. The differential cross-section for the first channel remained almost constant within the measured energy range, while the cross-section for the second channel increased with energy. In both cases, the cross-sections reached their maximum value at the lowest scattering angle measured. The differential cross-sections were verified using a thick solid tritiated tungsten target. For assessing the tritium depth profile, only the reaction channel H-3(He-3,d)He-4 can be utilized.