5 Timing of Data Acquisition
For primary beam, target and horn monitoring, and to a lesser extent
hadron and muon monitoring, it is necessary to be able to associate
this data with that collected in the near detector for the same spill.
[fixme]:At this time it is unknown the exact method of doing this
correlation. At the very least it is possible to record the system
time when the callback is called. This time is easily accurate to
within 100 ms (with the use of NTP) however there is some delay
between the time of the beam spill and the time of the callback.
This delay is currently completely unknown in both magnitude and
stability. Ideally there will be a timestamp, backed up by GPS or
another suitably accurate clock, which can be read back by adding a
suitable entry in the list of devices. Whatever the method, the
following requirement will be met:
[requirement]:Provide data needed to correlate beam monitoring data
with the near detector data on a spill-by-spill basis. It is not in
the scope of this process to do this correlation.