Neutron Age in Mixtures of D₂O and H₂O

The neutron age for fission neutrons and Po-Be neutrons was measured in mixtures of D₂O and H₂O. The age was evaluated from the second moment of the slowing-down distribution at the 1.4-ev resonance of indium. The ages of fission neutrons at concentrations of 99.8, 99.0, 98.4, 95.3, 94.0, 91.8, 48.6% D₂O, and in pure H₂O were 109, 107, 106, 93, 86, 78, 38.6, and 31 cm², respectively. In the range from 100 to 90% D₂O, the rate of decrease of the age was approximately 4 cm² for each additional per cent of H₂O. The ages of Po-Be neutrons in 99.4, 48.6% D₂O, and in H₂O were 148, 72.5, and 55.7 cm², respectively.