¹⁴N₂O and ¹⁵N₂O Dosimeters for Mixed Gamma and Thermal-Neutron Radiation Fields

The nitrous oxide dosimeter will measure the absorbed dose in a mixed radiation field of gamma rays and thermal neutrons. The effect of the latter is due to the ¹⁴N(n,p)¹⁴C reaction (cross section 1.78 b). However, ¹⁵N₂O has an extremely small cross section for thermal neutrons (0.02 mb) and thus measures only the gamma dose. Our studies using ¹⁴N₂O - ¹⁵N₂O mixtures show that ¹⁴N₂O and ¹⁵N₂₀ dosimeters can discriminate between ionizing radiation and thermal-neutron effects.