Absolute hydrogen depth profiling using the resonant $^{1}$H($^{15}$N,$αγ$)$^{12}$C nuclear reaction

Abstract

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,αγ) 12 C reaction, resonant at 6.4 MeV 15 N beam energy.Here, the strongly anisotropic angular distribution of the emitted γ-rays from this resonance has been remeasured, 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 γ-ray detection efficiency. Finally, the absolute approach is illustrated using two examples.