Neutron activation analysis
If the nucleus of an atom is explosed to neutron radiation, some of the
target nucleus are hit and absorb a neutron. In this case a new nucleus
is build with mass number increased by one and charge number without change:
A neutron is absorbed by a kernel (K) of mass number m and charge number
x.
In most cases, the new nucleus is instable. it decays by emitting radiation.
A look at the isotop table of iridium shows, that natural iridium had two
stable components:
Ir191 and Ir193 are stable and can be found in nature.
According to the absorption scheme above, absorption would result in the
instable kernels Ir192 and Ir194 respectivly. Both kernels are decaying
with a short half time emitting specific beta radiation. This can be detected.
The intensity of radiation is proportional to the concentration of iridium.
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