iconaAPPENDIX


Neutron sources and detectors

Neutrons are neutral particles and therefore are not directly detectable. For this purpose, the secondary charged particles are exploited to generate elastic or inelastic reactions induced by the primary neutrons. Such reactions will have a certain probability of occurring, expressed by the cross section, which is dependent on the energy of the incident neutron. Some reactions will be more suitable for the detection of thermal or fast neutrons, specific by the cross section. Epithermal neutrons are usually detected through the same reactions used for the detection of thermal ones. Such reactions can also be from cross sections with high resonances for well-determined energy values in the epithermal interval.

Neutron spectrometry is complex and involves the use of different detectors in the thermal, epithermal and fast energy ranges. Spectrometry of fast neutrons (up to 20 MeV) can be performed with different detection techniques that require the use of deconvolution algorithms for the reconstruction of the incident spectrum. The neutron spectrometry in the whole range of epithermal energies (0.5 eV - 100 keV) is very complex. In this energy interval, it may be useful to calculate the shape of the a priori energy distribution using numerical algorithms such as Monte Carlo simulations.

Some reactions of interest for neutron detection are listed and commented in the following document: