Re: Trigger formation times

Chris Walter (walter@cithe504.cithep.caltech.edu)
Thu, 21 Sep 1995 14:15:16 -0700 (PDT)

> I don't know what you mean by "jitter". Is it the FWHM around the average
> time delay, or the maximum deviation from average or what?
>
> I'm also going to presume that you don't care about things like PMT transit
> times; such effects make a difference when you talk about "0.1us" for the
> CSPAM, but if your interest is on the microsecond scale then we can just
> deal with delays in the trigger electronics.
>

I was talking about delays in the electronics themselves. Also
jitters in the electronics due to things like clocks in the systems.
For example: the SMT has one shots and the LIP has a fixed digital delay.

>
> Please note that in the current scheme of things, FMTs and HIPTs trigger
> WFD readout, but CSPAMs do not. And, being monopole triggers, the wider
> (>~10us) window for FMTs and HIPTs is appropriate.
> --

What you say is true but the CSPAM is still plugged in to the stop
master(anything can stop the system as it will automatically be
restarted at the end of event). The idea here was that even though
we weren't reading out on CSPAM, relative trigger time info might still
be useful. So if the CSPAM is the first trigger that shows up, the
you just see 0 in its spot. Now by looking at how much longer it took
for LIP triggers to arrive after that I was pretty sure that the
trigger was showing up only a few 100 ns after the event but I wanted
to make sure.

Another thing to keep in mind is that the stop master has 100 ns of
jitter due to its internal clock.

-Chris