Question

8. What thickness of cadmium is needed to reduce the intensity of an incident beam of thermal neutrons to 10% of its original level? Assume a thermal neutron cross section of 2520 barns, an atomic mass of 112.411 amu and a specific gravity of 8.65.

Answer 1

The intensity of neutron beams after passing a distance d in a material is given by

Where

Here, A, atomic weight = 112.411 g/mol

The specific gravity of cadmium = 8.65 g/cm^3

The Avogadro number NA = 6.022*10^23

, the cross section = 2520 barns = 2520*10^-24 cm^2

So,

So, for having I = 0.1I₀