Improved accuracy of γ-ray intensities from basic principles for the calibration reaction 14N(n,γ)15N

The 14N(n,γ)15N reaction is a primary source of high-energy γ rays for use in the calibration of detectors for other neutron-capture reactions. The γ-ray intensities of 15N produced by thermal neutron capture and the γ-ray detection efficiency function have been simultaneously determined from γ-peak areas alone using the basic principle of intensity balance. A least-squares fit was made to a new type of intensity balance calculation, combined with traditional efficiency fitting of radioactive sources. This latter ensures the compatibility with low-energy efficiencies, while providing an unbiased efficiency function for higher (up to 10 MeV) γ-ray energies. The calculation is based on the assumption that the 15N decay scheme is complete. From the internal consistency of the resulting intensities, it is believed that they are more accurate than previously published values. The same is true for the derived efficiency function