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McStas: ILL_H15_D11 Instrument at ILL

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

The ILL_H15_D11 Instrument

D11 at the ILL: Lowest momentum transfer, lowest background small-angle neutron scattering instrument


  • Site: ILL
  • Author: FARHI Emmanuel (
  • Origin:ILL
  • Date: 2012
  • Version: 1.0



D11 is the archetype of a long, pinhole geometry instrument for small angle 
neutron scattering (SANS), designed for the study of large scale structures in 
soft matter systems, chemistry, biology, solid state physics and materials science. 

This model allows to specify the collimation length, i.e. the free path between 
the end of the guide and the sample location. When Lc=1.5 m, the intensity is 
maximal, but Q-resolution (divergence) is degraded. The Lc=40.5 m configuration
is the low-Q one.
The collimation can also be given as predefined configuration 'iLc' starting from 0

  iLc ={ 1.5, 2.5, 4, 5.5, 8, 10.5, 13.5, 16.5, 20.5, 28, 34, 40.5}

so that e.g. iLc=5 corresponds with a 10.5 m collimation
The quality of the collimation section can be specified among a set of glass
pre-set specifications. The available configurations are:

              | Borkron_1972   Borkron_2003    Borofloat_2001  Borofloat_2003
Chamfers [mm] | 0.2            0.2             0.8             0.2                    
Wavyness [rad]| 2.5e-5         1e-4            8e-4            2e-4                

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
Lambda Angs neutron wavelength reaching D11 sample 4.51
Config string guide configuration. Must be one of Borkron_1972 Borkron_2003 Borofloat_2001 Borofloat_2003 "Borkron_1972"
Lc m guide collimation, i.e. free path between end of guide and sample location. Must be one of 40.5, 34, 28, 20.5, 16.5 13.5 10.5, 8, 5.5, 4, 2.5, 1.5 0
iLc index guide collimation predefined length 5
Chamfers m chamfers width (input/output movable guide section+longitudinal top/bottom sides) 0.0002
Waviness rad movable guide Waviness 2.5e-5


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

Generated automatically by McDoc, Peter Willendrup <> / Wed Jan 12 15:13:21 2022

Last Modified: Wednesday, 12-Jan-2022 16:13:21 CET
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