Gaussian

Usually, instrument response function is modeled as the normalized gaussian distribution.

\[\begin{equation*} {IRF}(t) = \frac{1}{\sigma \sqrt{2\pi}}\exp\left(-\frac{t^2}{2\sigma^2}\right) \end{equation*}\]

Full Width at Half Maximum (fwhm) is \(2\sqrt{2\log 2} \sigma\).