Absolute hydrogen depth profiling using the resonant 1H(15N,αγαγ)12C nuclear reaction

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 11H(1515N,αγαγ)1212C reaction, resonant at 6.4 MeV 1515N beam energy. Here, the strongly anisotropic angular distribution of the emitted γγ-rays from this resonance has been re-measured, resolving a previous discrepancy. Coefficients of (0.38 ±± 0.04) and (0.80 ±± 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 ±± 1.5) eV, 10% higher than previously reported. A simple working formula for the hydrogen concentration is given for cases with known γγ-ray detection efficiency. Finally, the absolute approach is illustrated using two examples.