A few problems slowed re-start this evening. When I test the daq
i see missing all 16 LTofbot, RtofTOP. But have to wait for search
to finish as D-tunnel was already closed
Ltofbot problem was simply a badly seeded cable, fixed trivially
Rtoftop problem was instead due to a failing lecroy 4418 delay unit in
slot 2. swapped with a spare in e-pool, now there is too little rate from
the right (cosmics). I swapped in the 4418 on crate right, slot 11
(neutrons), still the smae thing. As some of you know, the 4418 comes in
different flavours (delay tabs = 1,2, 8 ns...) but are undistinguishable
from the outside. It turns out that the two new units I swapped in were
set for 1 ns, whereas we want 2 ns. Hence few top/bot coincs on the right.
Finally, I swap in the 4418 from crate left, slot 11. This is indeed 2 ns.
On the more positive side, I incidentally found what would have been a
nasty problem for the neutron counters in the days ahead (i.e. having
delay units set for different tabs).
Now the cosmic rate seems fine, 400-450 Hz (I expected 500...) with some
coincs are missing because of bad cables (lemo!) but they are both L16
and R16 so I'll leave them there for tonight.
In between, the same problem w/ coda that karen described yesterday: no
physics events. This could be due to a missing link in the ecl cable that
give the fastbus crates a backplane trigger to initiate readout. However,
again "fixing" the cable and cycling the crate helped. Tomorrow there will
be a permanent fixture of this problem.
regards
-- tancredi
________________________________________________________________________________
Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
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