Preparation of a liquid nitrogen target for measurement of γ-rays in the 14N(n, γ)15N reaction as an intensity standard in energy regions up to 11 MeV

We have developed a liquid nitrogen (N2) target that allows us to clearly measure γ-rays below 2 MeV and to improve neutron beam availability. The intensity of the prompt 2223 keV γ-ray from the 1H(n, γ) reaction in the present target could be reduced to about 160 in comparison with the one in the commercially available melamine (C3H6N6) target. The statistics of the full-energy-peak counts were improved by factors of 15-30 and about 4 in the energy regions below and above 2 MeV, respectively.