AbstractThe attenuation of 14.1-Mev neutrons in water has been studied under conditions simulating an isotropic point source of monoenergetic neutrons in an infinite water medium. The migration area of thermal neutrons (〈r2〉th/6) was found to be 156±6 cm2. The“age”of indium resonance neutrons was measured to be 150±6 cm2. Fast neutron dose measurements are in agreement with the theoretical calculations of Goldsteinet al.