[ Identification | Description | Input parameters | Links ]

The DiskChopper Component

Based on Chopper (Philipp Bernhardt), Jitter and beamstop from work by Kaspar Hewitt Klenoe (jan 2006), adjustments by Rob Bewey (march 2006)

Identification

• Site:
• Author: Peter Willendrup
• Origin: Risoe
• Date: March 9 2006

Description

Models a disc chopper with nslit identical slits, which are symmetrically distributed
on the disc. At time t=0, the centre of the first slit opening will be situated at the
vertical axis when phase=0, assuming the chopper centre of rotation is placed BELOW the beam axis.
If you want to place the chopper ABOVE the beam axis, please use a 180 degree rotation around Z
(otherwise unexpected beam splitting can occur in combination with the isfirst=1 setting, see
related bug on GitHub)

For more complicated gemometries, see component manual example of DiskChopper GROUPing.

If the chopper is the 1st chopper of the instrument, it sets t time with phase
- Only relevant for when using continuous source modules.

Example: DiskChopper(radius=0.2, theta_0=10, nu=41.7, nslit=3, delay=0, isfirst=1) First chopper
DiskChopper(radius=0.2, theta_0=10, nu=41.7, nslit=3, delay=0, isfirst=0)

Input parameters

Parameters in boldface are required; the others are optional.

Name	Unit	Description	Default
theta_0	deg	Angular width of the slits.	0
radius	m	Radius of the disc	0.5
yheight	m	Slit height (if = 0, equal to radius). Auto centering of beam at half height.
nu	Hz	Frequency of the Chopper, omega=2*PI*nu (algebraic sign defines the direction of rotation)
nslit	1	Number of slits, regularly arranged around the disk	3
jitter	s	Jitter in the time phase	0
delay	s	Time 'delay'	0
isfirst	0/1	Set it to 1 for the first chopper position in a cw source (it then spreads the neutron time distribution)	0
n_pulse	1	Number of pulses (Only if isfirst)	1
abs_out	0/1	Absorb neutrons hitting outside of chopper radius?	1
phase	deg	Angular 'delay' (overrides delay)	0
xwidth	m	Horizontal slit width opening at beam center	0
verbose	1	Set to 1 to display Disk chopper configuration	0

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

Links

• Source code for DiskChopper.comp.

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[ Identification | Description | Input parameters | Links ]

Generated on 2023-09-19 20:01:36

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Last Modified: Tuesday, 17-Sep-2024 05:31:14 CEST