Analysis by neutrons activation

Theγ method consists in irradiating a sample and a standard of known composition in a thermal neutrons flow, that is to say very slow neutrons. An atomic nucleus of chemical symbol X, with Z as atomic number and A as atomic mass captures with an intrinsic probability called efficient section σ, a neutron, forming a radioactive nucleus with the same atomic number Z but with an atomic mass equal to A+1. This nucleus transmutes in general by beta radioactivity in a nucleus of an other element, symbol Y, atomic number Z+1, and the complete reaction chain is: AZ X (steady non excited) + 10 n (step of capture) ----> A+1Z X (radioactive) --->A+1Z+1 Y*(steady excited) + e-(electron) + ν(anti neutrino) (step of transmutation beta radioactivity---> A+1Z+1 Y (steady non excited)+ γ (step of deexcitation). (N.C.)