Resonant nuclear reactions are a powerful tool for the determination of the amount and profile of hydrogen in thin layers of material. Usually, this tool requires the use of a standard of well-known composition. The present work, by contrast, deals with standard-less hydrogen depth profiling. This approach requires precise nuclear data, e.g. on the widely used $^{1}$H($^{15}$N,$alphagamma$)$^{12}$C reaction, resonant at 6.4,MeV $^{15}$N beam energy. Here, the strongly anisotropic angular distribution of the emitted $gamma$-rays from this resonance has been re-measured, resolving a previous discrepancy. Coefficients of (0.38$pm$0.04) and (0.80$pm$0.04) have been deduced for the second and fourth order Legendre polynomials, respectively. In addition, the resonance strength has been re-evaluated to (25.0$pm$1.5),eV, 10% higher than previously reported. A simple working formula for the hydrogen concentration is given for cases with known $gamma$-ray detection efficiency. Finally, the absolute approach is illustrated using two examples.
تحميل البحث