14.92  The SANS_Guinier McStas Component

Sample for Small Angle Neutron Scattering, Guinier model

Identification

• Author: Henrich Frielinghaus

• Origin: FZ-Juelich/FRJ-2/IFF/KWS-2

• Date: Sept 2004

Description

Sample that scatters with a Guinier shape. This is just an example where analytically an integral exists. The neutron paths are proportional to the intensity (low intensity > few paths).

Guinier function (Rg) a = Rg*Rg/3 propability_unscaled = q * exp(-a*q*q) integral_prop_unscal = 1/(2*a) * (1 - exp(-a*q*q))

propability_scaled   = 2*a * q*exp(-a*q*q) / (1 - exp(-a*q*q))

integral_prop_scaled = (1 - exp(-a*q*q)) / (1 - exp(-a*qmax*qmax))

In this simulation method many paths occur for high propability. For simulation of low intensities see SANS_AnySamp.

Sample components leave the units of flux for the probability of the individual paths. That is more consitent than the Sans_spheres routine. Furthermore one can simulate the transmitted beam. This allows to determine the needed size of the beam stop. Only absorption has not been included yet to these sample-components. But thats really nothing.

Example: SANS_Guinier(transm=0.5, Rg=100, qmax=0.03, xwidth=0.01, yheight=0.01, zdepth=0.001)

Input parameters

Parameters in boldface are required; the others are optional.

Links

• Component source code found in file SANS_Guinier.comp.

• Sans_spheres component