Thanks for your great concerning and carefully reading my mail!
Here are some answers to the questions asked by some of you.
Q.) I don't understand what you are saying about cross-SM slow monopoles.
A.) Since the WFD stop master is based on each SM, we have to worry more
about the coincidence triggers or non-coincidence triggers for the Caltech
Slow MNP trigger. The reason is, as I said, that for a coincidence
trigger we plan to read out every channel in the SM while for a single
face trigger event we are only going to read out several channels. If
a monopole crosses three SM's, we may get three single face triggers from
three SM's even though it's a real coincidence trigger. What I was trying
to say is that if a monopole event crosses two SM's we should get at least
one coincidence trigger from one SM because we have three horizontal layers.
Therefore, my argument is that we will be fine because we get one SM
very detailed info plus another several channels info from the other SM.
This argument is just try to tell that one SM based electronics is
still fine for the Caltech SLow MNP trigger. Now for a monopole event
crossing more than three SM's, we will get three single face triggers
in three SM's. Hence, we cannot get any detailed information at this
one SM based configuration. But, the thing is not so bad because the
probability to get that large angle events is less that 0.8%.
Q.) I am not sure that UTC time will be useful for TOF calculation. We
need resolution good enough for FMT searches.
A.) You have already known how good the UTC clock is. But one thing which
you forgot is that the FMT is two SM's trigger, which means if a monopole
crosses two SMs, the WFD in two SM's will either be stopped at the same
time or we can get the time information from the stop master which should
be better than 100ns. For very fast monopole, this resolution is certainly
not good enough, but remember that I have modified the ERP which can give
us a better inter-SM time.
Q.) I am worried that your extra delay of the stop in the case of a late
CIT trigger will cause problems.
A.) Good worry! At first, I bet that it will not happen very
often as I discussed in my last mail. It seems to me that we all
agree that the dead time is not a problem by using this feature.
You are worried about the readout system. If we plan to use smart
readout to read different time window, adding this extra delay is
not going to give any trouble. One the other hand, if we want to
keep simple and read out only 1ms, we have to be more careful to
select the readout window. To cover this problem and keep the
readout simple, we probabily want to read 2ms. It sounds not
good, but it's really determined by how good our zero suppression
works. With 2mV threshold (suppression), it has only 50 pulses
within 1ms window. (note that I used 50KHz trigger rate for 2mV
threshold.)
Well, I am waiting for the answer from WFD designers. I thought
that we had asked someone to design a smart readout system,
hadn't we?
Q.) Did you miss up the EAST face for the monopole trigger?
A.) Nope, but I did miss typing it in my mail.
Q.) Should the WFD clear by the computer busy be used regarding
the cross-talk?
A.) Both bit-set and computer busy methods could be stopped if we don't want
to use. The way which I built the computer busy to clear the system is that
I have sent the signal out and then use an external input to clear. Hence,
we can disconnect the input line to forget it. Another advantage of using
this external I/O is that we can add other external clear if we want to.
Now back to you discussion about the cross-talk, I assume that
the cross-talk which you talked about is inside the stop master.
If that is the case, I shall find it out and solve the problem. I
don't know if you guys have seen any cross-talk mistake in the
computer busy signal before. Since we have several choices, we
can decide which way is the best in the real ACQ system.
Q.) Why are you doing CAMAC writes only 4 bits at a time?
A.) Because of I/O limit, I cannot have sixteen bit write lines. Instead, I
used four write lines. Apparently, it's slower than 16 lines. But since the
initialization only happens at the begining of each RUN, it's not going to
be a problem.
Q.) Did you have input for HIPT (Highly Ionization Particle Trigger)?
A.) Yes, I have two extra inputs reserved for those who need them.
Q.) What is the plan for the WFD readout?
A.) It's too tough for me to answer. As I mentioned a little bit
in above, I don't know any decision being made on that issue.
But, I bet that you will see the real discussion on it soon. So,
keep your eyes open!
Q.) Should we keep these old WFD for the FMT/CSPAM use?
A.) Ask our boss! It's a good idea to keep the old WFD for the
FMT use because with 5:1 attenuation, we can get a very good
resolution for big pulse and it's linear.
Ciao,
Rongzhi