[ Identification | Description | Input parameters | Links ]

The Selector Component

velocity selector (helical lamella type) such as V_selector component

Identification

• Site:
• Author: Peter Link, Andreas Ostermann
• Origin: Uni. Gottingen (Germany)
• Date: MARCH 1999

Description

Velocity selector consisting of rotating Soller-like blades
defining a helically twisted passage.
Geometry is defined by two identical apertures at 12 o'clock position,
The origin is at the ENTRANCE of the selector.

Example: Selector(xmin=-0.015,  xmax=0.015,  ymin=-0.025, ymax=0.025, length=0.25,
nslit=72,d=0.0004, radius=0.12, alpha=48.298, nu=500)
These are values for the D11@ILL Dornier 'Dolores' Velocity Selector (NVS 023)

%VALIDATION
Jun 2005: extensive external test, one minor problem
Jan 2006: problem solved (for McStas-1.9.1)
Validated by: K. Lieutenant

%BUGS
for transmission calculation, each neutron is supposed to be in the guide centre

Input parameters

Parameters in boldface are required; the others are optional.

Name	Unit	Description	Default
xmin	m	Lower x bound of entry aperture	-0.015
xmax	m	Upper x bound of entry aperture	0.015
ymin	m	Lower y bound of entry aperture	-0.025
ymax	m	Upper y bound of entry aperture	0.025
length	m	rotor length	0.25
xwidth	m	Width of entry. Overrides xmin,xmax.	0
yheight	m	Height of entry. Overrides ymin,ymax.	0
nslit	1	number of absorbing subdivinding spokes/lamella	72
d	m	width of spokes at beam-center	0.0004
radius	m	radius of beam-center	0.12
alpha	deg	angle of torsion	48.298
nu	Hz	frequency of rotation, which is ideally 3956*alpha*DEG2RAD/2/PI/lambda/length	500

AT (	,	,		) RELATIVE		Generate
ROTATED (	,	,		) RELATIVE

Links

• Source code for Selector.comp.
• See also Additional notes March 1999 and Jan 2000.

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[ Identification | Description | Input parameters | Links ]

Generated on mcstas 3.5.32

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Last Modified: Monday, 30-Jun-2025 11:05:09 CEST