The Resonant Absorption of γ-Rays in 14N

Using a nitrogen filled proportional counter the resonant absorption of γ-rays to the 8.06 MeV level in 14N has been observed by means of the 14N(γ,p)13C reaction. The inverse reaction 13C(p,γ)14N at the 554keV resonance was used as the source of γ-rays. The γ-ray flux was accurately measured with a scintillation counter and from the results the width of the 8.06 MeV level for ground state γ-ray transitions was found to be 10.5 ± 0.6 eV. This is in good agreement with the value obtained from the results of Seagrave on the inverse reaction 13C(p,γ)14N. Since the γ-ray energy is a function of angle due to a Doppler shift the resonant character of the absorption has been shown by varying the angle of the proportional counter with respect to the proton beam direction and noting the change in proton yield.