Ideal model of a chopper situated at Z=0. If a photon arrives at the chopper plane
at a time of t = [t0 +-n*T: t0 +-n*T +tau], where T is the period of the chopper, t0 the initial delay
and tau the opening time of the chopper, it is left untouched - otherwise it is ABSORBed.
If on a continous source the isfirst parameter may be used. In this case the photon time is _defined_
by the chopper. In other words no photons are absorbed, the photon time is merely sampled within the chopper window.
t_rise is the rise-time of the chopper opening giving a trapezoidal shape.
Limitations: this component does not take chopper geometry into account. If isfirst only samples in the first chopper opening window.
Parameters in boldface are required;
the others are optional.
Initial delay of the opening time
Period of the chopper
Opening time of the chopper
height of the chopper opening
width of the chopeper opening
is the chopper the first chopper on a continous source.
Rise time of the chopper pulse.
Timing jitter in terms of the opening time tau. For each ray the opening window will be shifted by a random amount within t=[-tjit*.5*tau,tjit*.5*tau]