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McStas: SANS_Guinier Component

[ Identification | Description | Input parameters | Output parameters | Links ]

The SANS_Guinier Component

Sample for Small Angle Neutron Scattering: Guinier model


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


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)

WARNING: This is a contributed Component.

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
transm 1 : (coherent) transmission of sample for the optical path "zdepth" 0.5
Rg Angs : Radius of Gyration 100
qmax AA-1 : Maximum scattering vector 0.03
xwidth m : horiz. dimension of sample, as a width (m) 0.01
yheight m : vert.. dimension of sample, as a height (m) 0.01
zdepth m : thickness of sample (m) 0.001

Output parameters

Name Unit Description Default


  • Source code for SANS_Guinier.comp.
  • Sans_spheres component

[ Identification | Description | Input parameters | Output parameters | Links ]

Generated automatically by McDoc, Peter Willendrup <> / Wed Apr 19 10:57:33 2017

Last Modified: Wednesday, 19-Apr-2017 12:57:33 CEST
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