Short-lived Elementary Particles in Atoms and Molecules

Thermal neutrons (the energy distribution is comparable to that of gas molecules at ordinary temperature) 

Slow neutrons (neutrons with energies of the order of 1 eV to 1 keV are also called resonance neutrons, because maxima of absorption are observed in this energy range) 

In contrast to protons, deuterons, a particles and other particles carrying positive charges, neutrons do not experience Coulomb repulsion by nuclei. Low-energy (thermal and slow) neutrons are very effectively absorbed by a great number of nuclei, giving rise to nuclear reactions. Elements such as B, Cd, Sm, Eu, Gd and Dy are used as excellent neutron absorbers. 

Detection of neutrons is based on ionization processes caused by the products of their interactions (nuclear reactions or collisions) with nuclei. 

6 Short-lived Elementary Particles in Atoms and Molecules 

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