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14.30 The StatisticalChopper McStas Component
Statistical (correlation) Chopper
Identification
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Author: C. Monzat/E. Farhi/S. Rozenkranz
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Origin: ILL
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Date: Nov 10th, 2009
Description
This component is a statistical chopper based on a pseudo random sequence that the user can specify. Inspired from DiskChopper, it should be used with SatisticalChopper_Monitor component.
Example: StatisticalChopper(nu=1487*60/255) use default sequence
Input parameters
Parameters in boldface are required; the others are optional.
|
Name |
Unit |
Description |
Default |
|
|
|||
|
radius |
m |
Radius of the disc |
0.5 |
|
yheight |
m |
Slit height (if = 0, equal to radius). Auto centering of beam at half height. |
0 |
|
nu |
Hz |
Frequency of the Chopper, omega=2*PI*nu (algebraic sign defines the direction of rotation) |
|
|
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 |
|
abs_out |
0/1 |
Absorb neutrons hitting outside of chopper radius? |
1 |
|
phase |
deg |
Angular ’delay’ (overrides delay) |
0 |
|
verbose |
1 |
Set to 1 to display Disk chopper configuration |
0 |
|
n_pulse |
1 |
Number of pulses (Only if isfirst) |
1 |
|
sequence |
str |
Slit sequence around disk, with 0=closed, 1=open positions. NULL or "" will set a default sequence. |
"NULL" |
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Links
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Component source code found in file StatisticalChopper.comp.
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R. Von Jan and R. Scherm. The statistical chopper for neutron time-of-flight spectroscopy. Nuclear Instruments and Methods, 80 (1970) 69-76.
