Resonant gamma-ray yields from the 15N(p, alpha-gamma)12C reaction as a function of channeled proton energy and nb-0.2 at.%15N crystal orientation

The resonant reaction 15 N(p, αγ) 12 C and proton channeling technique are used to determine the lattice location of nitrogen impurity atoms and investigate flux peaking of channeled protons in axial and planar channels. At proton energies equal to or somewhat higher than the resonance value E p = 898 keV angular scans were carried out across major crystal directions. The nitrogen atoms are shown to occupy octahedral interstitial sites in the Nb lattice. The angular dependence of the γ-ray yield on the energy of protons channeled along the < 100 > axis or (110) plane exhibits oscillations. The measured location of the first oscillation peak in the proton energy scale is in satisfactory agreement with calculations.