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McStas: V_selector Component

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

The V_selector Component

Velocity selector.


  • Author: Kim Lefmann
  • Origin: Risoe
  • Date: Nov 25, 1998
  • Version:(Unknown)


Velocity selector consisting of rotating Soller-like blades
defining a helically twisted passage.
Geometry defined by two identical, centered apertures at 12 o'clock
position, Origo is at the centre of the selector (input is at -zdepth/2).
Transmission is analytical assuming a continuous source.

Example: V_selector(xwidth=0.03, yheight=0.05, zdepth=0.30, radius=0.12, alpha=48.298, length=0.25, d=0.0004, nu=20000, nslit=72)
These are values for the D11@ILL Dornier 'Dolores' Velocity Selector (NVS 023)

Jun 2005: extensive external test, no problems found
Validated by: K. Lieutenant

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
xwidth m Width of entry aperture 0.03
yheight m Height of entry aperture 0.05
zdepth m Distance between apertures, for housing containing the rotor 0.30
radius m Height from aperture centre to rotation axis 0.12
alpha deg Twist angle along the cylinder 48.298
length less than zdepth [m] Length of cylinder/rotor 0.25
d m Thickness of blades 0.0004
nu Hz Cylinder rotation speed, counter-clockwise, which is ideally 3956*alpha*DEG2RAD/2/PI/lambda/length 300
nslit 1 Number of Soller blades 72


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

Generated automatically by McDoc, Peter Willendrup <> / Fri Sep 23 18:47:16 2022

Last Modified: Friday, 23-Sep-2022 20:47:16 CEST
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