Probabilistic Estimate of vertical bar F-oa vertical bar from FEL Data

The method of the joint probability distribution function was applied in order to estimate the normal structure factor amplitudes of the anomalous scatterer substructure in a FEL experiment. The two-wavelength case was examined. In this, the prior knowledge of the moduli vertical bar F-1(+)vertical bar, vertical bar F-1(-)vertical bar, vertical bar F-2(+)vertical bar, vertical bar F-2(-)vertical bar was used to predict the value of vertical bar F-oa vertical bar, which is the structure factor amplitude arising from the normal scattering of the heavy atom anomalous scatterers. The mathematical treatment provides a solid theoretical basis for the RIP (Radiation-damage Induced Phasing) method, which was originally proposed in order to take the radiation damage induced by synchrotron radiation sources into account. This was further adapted to exploit FEL data, where the crystal damage is usually more massive.