[Nexus-developers] Some more definitions
freddie.akeroyd at stfc.ac.uk
freddie.akeroyd at stfc.ac.uk
Thu Oct 29 16:42:00 GMT 2009
Hi Mark,
> -- I am missing something important: IMHO each TOF instrument has a
> pulse defining chopper. This is the
> chopper, which sends the signal to start counting time-of-flight.
> There may be tons more choppers but they
> are only there to have the neutron packet win the Miss Neutron
> Pulse
> Beauty competition. From what I know,
> the distance of the pulse defining chopper to the sample is very
> important in order to calculate the total flight
> length of the neutron for DA. Now, no chopper was in the tofraw on
> the wiki. I think I have to add this. Any
> opinions?
We have TOF instruments with no choppers at ISIS, the SXD instrument
being an example - they get their timing signal from the synchrotron
extraction pulse. Thus a chopper should be optional in TOFRAW. A chopper
will, however, always be present on a TOF instrument at a reactor
source.
Regards,
Freddie
--
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