Neutron data for standards

The majority of basic and applied measurements in neutron physics are performed relative to cross-section standards. It is therefore essential that these standards are continuously improved and their underlying physical mechanisms are understood.

The OECD and the Data Centre of the International Atomic Energy Agency (IAEA) have standards subcommittees to identify needs for new standards, for improvements of established standards and to regularly update the neutron standards data files. These standards data files are publicly accessible at no cost and are of major interest to various disciplines in science (physics, medicine, astrophysics) and technology. The detailed requirements for neutron data measurements, and in particular for improvements of the standards database, are collected in the high priority list of the NEA. The priorities for the measurement programme at IRMM are defined in close co-operation with the NEA databank and participating in a Co-ordinated Research Program (CRP) of the IAEA on the 'Improvement of the Standard Cross-sections of Light Elements'.

For example, the ¹⁰B reaction cross section is amongst the most important standards used in neutron measurements. Over the years IRMM has improved the data and this work has resulted in better branching ratio values solving the discrepancy observed for the ¹⁰B(n,α) reaction during a standards’ evaluation.

In the field of neutron standards IRMM is the only European laboratory capable of providing cross-section data over the complete neutron energy range from a few meV up to about 20 MeV with the required accuracy.