Anomalous radiative capture of protons in thick targets

The radiative capture of protons by the nuclei /sup 12/C, /sup 16/O, /sup 24/Mg, and /sup 28/Si in the energy range 400--2500 keV has been studied in thick targets. It is found that in capture of protons near the 1699-keV resonance in the reaction /sup 12/C(p, ..gamma..)/sup 13/N and possibly in the reaction /sup 16/O(p, ..gamma..)/sup 17/F the ..gamma..-ray spectrum from thick targets of the same total thickness. A similar phenomenon has not been observed for five other similar resonances.