[ Identification | Description | Input parameters | Output 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

• Author: Peter Willendrup
• Origin: Risoe
• Date: March 9 2006
• Version: 1.11

Description

Models a disc chopper with n identical slits, which are symmetrically disposed
on the disc. At time t=0, the centre of the first slit opening will be situated at the
vertical axis.

Possibly, the slits can have central absorbing inserts ('beamstops'). 

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(R=0.2, theta_0=10, omega=2500.0, n=3, t_0=0, IsFirst=1) First chopper
         DiskChopper(R=0.2, theta_0=10, omega=2500.0, n=3, t_0=0, IsFirst=0)

Example values: theta_0=10 h=0.2 R=0.5 omega=2500 n=3 t_0=0 n_pulse=1 j=0 wc=0

Input parameters

Parameters in boldface are required; the others are optional.

Name	Unit	Description	Default
theta_0	deg	Angular width of the slits.
R	m	Radius of the disc
h	m	Slit height (if = 0, equal to R). Auto centering of beam at h/2.	0
omega	rad/s	Angular frequency of the Chopper (algebraic sign defines the direction of rotation)
n	1	Number of slits	3
j	s	Jitter in the phase	0
theta_1	deg	Angular width of optional beamstop in chopper windows	0
t_0	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
phi_0	deg	Angular 'delay' (suppresses t_0)	0
w	m	'width' of slits for compatibility with Chopper.comp	0
wc	m	'width' of beamstops for compatibility with Chopper.comp	0
compat	1	Chopper placement compatible with original Chopper.comp	0

Output parameters

Name	Unit	Description	Default
Tg
T
To
Tc
delta_y
height

Links

• Source code for DiskChopper.comp.

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

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Fri Feb 10 11:36:23 2012

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Last Modified: Friday, 10-Feb-2012 12:36:23 CET