Several neutron sources, Am-Be, were standardized by the Method of Activating a Manganese Sulphate Bath. The fountains, placed inside cylindrical vessels, were immersed in the center of spherical tanks of 50 cm and 100 cm in diameter, respectively circulating and static baths containing a concentrated solution of manganese sulphate in water. For the measurement of the neutron emission rate, in addition to the rate of gamma counts, bath efficiency and fraction of the total number of thermal neutrons absorbed by manganese, factors related to fast reactions with oxygen and sulfur, neutron fraction absorbed by the source itself and coating and neutron leakage of the solution. The values obtained by the methods provided a good match with the values provided by the manufacturer of such sources.
