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McStas: SANS_Guinier

[ Identification | Description | Input parameters | Links ]

The SANS_Guinier Component


  • Site:
  • Author: Henrich Frielinghaus
  • Origin: FZ-Juelich/FRJ-2/IFF/KWS-2
  • Date: Sept 2004


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.
transm1(coherent) transmission of sample for the optical path "zdepth"0.5
RgAngsRadius of Gyration100
qmaxAA-1Maximum scattering vector0.03
xwidthmhoriz. dimension of sample, as a width0.01
yheightmvert.. dimension of sample, as a height0.01
zdepthmthickness of sample0.001


  • Source code for SANS_Guinier.comp.
  • Sans_spheres component

[ Identification | Description | Input parameters | Links ]

Generated on 2023-09-19 20:01:36

Last Modified: Wednesday, 03-Jan-2024 19:59:10 CET
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