Material used to “decelerate” fast neutrons to low energies, since the fissionSee 'nuclear fission'. of the U-235 nuclei results in a better yield at low neutronUncharged elementary particle with a mass of 1.67492716 ·10... energies. Among others, light water, heavy waterDeuterium oxide, D2O; water containing two deuterium atoms i... and graphite are used as moderators.
Model representation of the moderator effect