Development of a 2D digital proton-proton scattering technique for hydrogen depth profiling

Measuring hydrogen concentration and determining its depth profile in different substrates has always been a major challenge for material science. Proton-proton scattering is a nondestructive technique for hydrogen analysis in thin samples. In this paper, the development of a 2D coincidence proton-proton spectroscopy was performed using a 3 MeV Van de Graaff accelerator. In the presented technique, the coincidence recording of the proton-proton scattering events by a waveform digitizer provides the sum-difference energy spectrum of the correlated events. By determining the proton energy loss in the sample, the hydrogen depth profile was extracted. To correct the error in the counting efficiency due to the multiple scattering, the Monte Carlo simulation was performed using the Corteo code. The performance of the technique was tested by measuring the concentration of hydrogen on both sides of a thin layer of aluminum. The results confirmed that the established technique is sensitive enough to separate the hydrogen peaks of these two thin layers.