The D—D Reaction as a Standard Neutron Source

THE first of the two possible D—D reactions has long been used as a source of mono-energetic neutrons. To use it as a standard source of neutrons requires either the counting of all the neutrons, using, for example, a water-tank method, or the counting of the helium-3 particles, which is difficult because of their very short range. But if, with given conditions, the ratio of the number of helium-3 particles to the number of hydrogen-3 or hydrogen-1 particles from the second reaction is once found, then the neutron flux may afterwards be determined merely by counting the number of hydrogen particles, which is much easier owing to their greater range.