Absolute hydrogen depth profiling using the resonant 1H(15N,αγ)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 H-1(N-15,alpha gamma)C-12 reaction, resonant at 6.4 MeV N-15 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 +/- 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 gamma-ray detection efficiency. Finally, the absolute approach is illustrated using two examples. (C) 2016 Elsevier B.V. All rights reserved.