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McStas: Guide_channeled

[ Identification | Description | Input parameters | Links ]

The Guide_channeled Component

Neutron guide with channels (bender section).

Identification

  • Site:
  • Author: Christian Nielsen
  • Origin: Risoe
  • Date: 1999

Description

Models a rectangular guide tube centered on the Z axis. The entrance lies
in the X-Y plane.
The guide may be tapered, and may have vertical subdivisions (used for
bender devices).

There is a special rotating mode in order to approximate a Fermi Chopper
behaviour, in the case the neutron trajectory is nearly linear inside the
chopper slits, i.e. the neutrons are fast w/r/ to the chopper speed.
Slits are straight, but may be super-mirror coated. In this case, the
component is NOT centered, but located at its entry window. It should then
be shifted by -l/2.

Example: Guide_channeled(w1=0.1, h1=0.1, w2=0.1, h2=0.1, l=2.0,
R0=0.99, Qcx=0.0219, Qcy=0.0219, alphax=6.07, alphay=6.07, W=0.003, nslit=1,
d=0.0005, mx=1, my=1)

%BUGS
This component does not work with gravitation on. Use Guide_gravity.
This component does not work in multichannel focusing geometry.

Input parameters

Parameters in boldface are required; the others are optional.
NameUnitDescriptionDefault
w1mWidth at the guide entry
h1mHeight at the guide entry
w2mWidth at the guide exit0
h2mHeight at the guide exit0
lmLength of guide
R01Low-angle reflectivity0.995
QcAA-1Critical scattering vector0
alphaAASlope of reflectivity0
m1m-value of material. Zero means completely absorbing.0
nslit1Number of channels in the guide (>= 1)1
dmThickness of subdividing absorbing walls0.0005
QcxAA-1Critical scattering vector for left and right vertical mirrors in each channel0.0218
QcyAA-1Critical scattering vector for top and bottom mirrors0.0218
alphaxAASlope of reflectivity for left and right vertical mirrors in each channel4.38
alphayAASlope of reflectivity for top and bottom mirrors4.38
WAA-1Width of supermirror cut-off for all mirrors0.003
mx1m-value of material for left and right vertical mirrors in each channel. Zero means completely absorbing.1
my1m-value of material for top and bottom mirrors. Zero means completely absorbing.1
nuHzRotation frequency (round/s) for Fermi Chopper approximation0
phasedegPhase shift for the Fermi Chopper approximation0
AT ( , , ) RELATIVE
ROTATED ( , , ) RELATIVE

Links


[ 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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