Neutron fluence
= Neutron fluence
{title2=$\Phi(t)=\int_0^t\phi(t')\,dt'$}
The time integral of scalar <neutron flux>, with inverse-area units. Multiplication by a constant microscopic reaction <collision cross-section> gives a dimensionless exposure parameter. A single integrated exposure does not specify how the neutron energy distribution varied during irradiation.