Based on Chopper (Philipp Bernhardt), Jitter and beamstop from work by
Kaspar Hewitt Klenoe (jan 2006), adjustments by Rob Bewey (march 2006)
Author: Peter Willendrup
Date: March 9 2006
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)
Parameters in boldface are required;
the others are optional.
Angular width of the slits.
Radius of the disc
Slit height (if = 0, equal to radius). Auto centering of beam at half height.
algebraic sign defines the direction of rotation
[Hz] Frequency of the Chopper, omega=2*PI*nu
Number of slits, regularly arranged around the disk
Jitter in the time phase
it then spreads the neutron time distribution
[0/1] Set it to 1 for the first chopper position in a cw source
Only if isfirst
 Number of pulses
Absorb neutrons hitting outside of chopper radius?