Consider a neutron transmission experiment through a \({ }^{232} \mathrm{Th}\) foil of thickness \(0.001 \mathrm{~cm}\). The neutron beam is mono-energetic with a certain energy. Density of the material of the foil is \(12 \mathrm{~g} / \mathrm{cm}^{3}\). If \(90 \%\) of the incident neutrons are lost on transit through the foil, find the total cross-section of \({ }^{232} \mathrm{Th}\) at that energy.