> Hi folks,
>
> Just some quick comments on Chris' last e-mail:
Thanks... I forgot that 1) there were no spare inputs on the STOP
master(although you could replace the CSPAM input if you had to) and
2) you can't have multiple stop times.
>
> I agree that the STOP MASTERs suffer from various problems since day one.
> That's why the fast stop we're testing has nothing to do with the
> STOP MASTER module.
I know this is going to sound schizophrenic but I would *rather* have
it implemented in the STOP master. Although it does have problems it
is the only thing that can cause a STOP(which is a nice feature) and I
have never seen an error I couldn't flag. The big worry is that the
WFDs get stopped and you don't know it. All that being said I
understand that you don't have much of a choice.
I know that Eric understands this but just for the others here is a
clip of a message I sent to Charlie explaining what kind of
backgrounds you can accidently introduce:
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This high energy early STOP thing makes me quite nervous. I guess
they don't really have a choice but if I understand what they are
doing they are bypassing the STOP master completely. This means that
for a class of events the STOP master will look like it went for about
1ms but in fact the WFDs will have been stopped much earlier. You
will need to look in another piece of equipment to see that. If
everything works then it should be OK. But if it screws up even a
small fraction of the time(imagine once per 100 runs or something)
then you might introduce horrible background problems into a monopole
analysis. The TOHM trigger will go off and you will think that the
WFDs went for 1-ms. Then when you look at the WFDs you will look at
the wrong place and instead of seeing a muon(for example) you will see
random radioactivity which might be consistent with SPE trains. So we
need to make sure it *really* works before we do this.
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Thanks for all your work and consideration. I'm not saying don't do
this I'm just saying be very careful.
-Chris