Neutron energy resolution in NaI detector
[math]\displaystyle{ E_n = \frac{m}{2}\left( \frac{d}{t_n} \right)^2 }[/math]
[math]\displaystyle{ \delta E_n = -2\ E_n \frac{\delta t_n}{t_n} = -\frac{2 sqrt{2}}{\sqrt{m} d}\ E_n^{3/2} \delta t_n }[/math]