Primary Standard of Neutron Emission

The Ionizing Radiation Department of the Slovak Institute of Metrology, in collaboration with its partner organization, the Institute of Nuclear and Physical Engineering of the Faculty of Electrical Engineering and Information Technology at STU, completed the project APVV-21-0170 in 2024, titled "Extension of the National Standard in a Key Area for the Slovak Economy."

The main achievement of the project is the development of a primary standard of dosimetric neutron radiation quantities, which ensures the realization of the unit at the highest level. At the same time, it enables high-level metrological measurements of an additional quantity—anisotropy. A dedicated device for anisotropy measurement was also designed and manufactured, allowing the directional dependence of neutron sources to be evaluated.

The primary method is based on the activation of manganese by neutrons in a manganese bath, followed by activity measurement using a NaI(Tl) scintillation detector of the radionuclide ⁵⁶Mn, which emits gamma radiation. This measurement method allows for the determination of neutron source emission with a standard uncertainty of up to 0.7%.

With this, the Slovak Institute of Metrology has joined a select group of metrology institutes worldwide that possess such a method.

Image: Manganese bath