slow neutrons

Neutrons of kinetic energy less than some specified value. This value may vary over a wide range and depends on the application. In reactor physics, the value is frequently chosen to be $1 eV$ ; in dosimetry, the effective cadmium cut-off is used.

Source:

PAC, 1982, 54, 1533 (Glossary of terms used in nuclear analytical chemistry (Provisional)) on page 1547