Hi tavi,
the cerenkov's are in the trigger just fine. I am finishing their new
set up with the new analog adders which we have tested and work well.
After this a cosmic run with only C in the trigger using the old and new
(see below) voltages would be nice but it has to be negotiated with the
Wch people.
I also fixed the flasher problem with LC0: the fiber was simply not
connected which of course also created a light leak there (I've not
tested for that again though).
Generally for the front boxes signals looked reasonable using a simple
"cosmic trigger" where at least to C tubes were required to fire. I had
to increase the voltages mostly in LC2 and RC2, so that typical pulse
heights moved from 50 mV to about 200 mV. I have not done anything for LC3
and RC3. However I later realized that this cosmic trigger is probably not
100 %clean i.e. 2fold "noise" random coincs are possible but I don't think
this is a huge problem for now. At this point the efficiency for flasher is
definitely 100 %. The flasher signal is in 0.5-1.0 V range but the cosmic
signal is at least 200 mV. So the efficiency should be high for cosmics as
well. ALl bets are off however when using the old analog adders since the
"sum analog" looks like a terrible square pulse and anyways the input is
out of the nominal range
Thew hall will be open at least until mid-week next week. On monday we are
set up to start cosmic runs (for efficiency studies) in earnest, using a pair
of tof *and* the start counter hanging vertically (I've created arrangements
for such set up). The start counter has just the right length to overlap
also the small C-boxes.
We need urgently the following info though:
_ the manufacturer recommended voltage for each tube in each box (may
require the hall open on monday). I mean the voltage for which each pmt
has a fixed gain (2e4). Ricardo pointed out that this should be our
reference set up. This is important for the rear boxes in particular.
You are the onlu person I know who can arrive at this information. Can you
please write a table ? we all need this info.
Once we are happy with all of the above and done with the start counter
we can think of trying a new set of flasher attenuators like the ones you used
in dtf so that the flasher light becomes comparable to the cosmic/e's
light. But first we need to measure cosmic efficiencies.
regards,
-- tancredi
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On Fri, 4 Oct 2002, Octavian F Filoti wrote:
>
> Hi Tancredi,
>
> I can come tomorrow (Saturday) at 12pm and stay till evening!
> I am going to make the trigger program working and get the Cherenkov ready
> in the trigger.
> Are you going to be here?!
> I also can come Saturday afternoon to fix anything else for Cherenkov's!
> P.S. I was sick with my stomach and I could not sleep during night, that's
> why I slept during day!
>
> -----------------------
> Octavian F Filoti
> Nuclear Physics Group
> Univ. of New Hampshire
> 9 Library Way
> Durham, NH 03824
> phone: (603)862-1691
> FAX: (603)862-2998
> email: ofiloti@unh.edu
>
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