Scattering intensity

For dilute solutions, the experimental scattering curve is given by: 

s : Modulus of the scattering vector, s = 4p(sinq)/l, 2q is the scattering angle and l = 0.15nm the wavelength
c : Concentration of the solute
I_s(s) : Intensity scattered by the solution
I_b(s) : Intensity scattered by the buffer
I_s,0, I_b,0 : Average intensities of the direct beam transmitted through the sample and the buffer respectively
D(s) : Detector response (in practice, the detectors present irregularities that lead to systematic errors if corrections are not made)

For concentrated solutions, the difference in absorption of the solution and the solvent must also be taken into account.

The geometrical structure information is obtained from the scattering intensity normalised to one electron in the solution usually obtained by reference to a standard sample.

Detector response	Homogeneous irradiation with a 55Fe radioactive source
Camera calibration	Conversion of channel number of the detector to the modulus of the scattering vector using a standard sample: Collagen (periodicity 65 nm), Tripalmitin (periodicity 4.06 nm)
Molecular weight calibration for proteins	A fresh solution of bovine serum albumin (BSA) of known concentration  (5-8mg/ml) is used as a reference
Sample measurement	For accurate measurements the scattering of the buffer at dialysis equilibrium should be measured BEFORE and AFTER the sample

For more details regarding data processing refer to PRIMUS manual