Cadmium 113 edge

113Cd has specific absorption cross-section. There is a cadmium cut-off energy (Cadmium edge) in the absorption cross-section. Only neutrons of kinetic energy below the cadmium cut-off energy (~0.5 eV) are strongly absorbed by 113Cd. Therefore cadmium is widely used to absorb thermal neutrons in a thermal neutron filters.

n+_{48}^{113}\textrm{Cd}  {\rightarrow} _{48}^{114}\textrm{Cd^{\star}} \rightarrow  _{48}^{114}\textrm{Cd} +\gamma

Cadmium cut-off energy
Neutrons of kinetic energy below the cadmium cut-off energy (~0.5 eV) are strongly absorbed by 113-Cd.
Source: JANIS (Java-based Nuclear Data Information Software); The JEFF-3.1 Nuclear Data Library

See above:

Cadmium