Column of Water Length

Column of Water Needed to Cut Photon Count in Half at 10 MeV

[math]\displaystyle{ e^{-n \sigma t} }[/math]

[math]\displaystyle{ n = \frac{atoms}{cm ^{3}} => \frac{\frac{g}{cm^{2}}{\frac{g}{mol}}} \times 6.022 \cdot 10^{23} \frac{atoms}{mol} => \frac{atoms}{cm^{3}} }[/math]