the gain matching was finished last night although some channels showed
pedestal shifts (I'll look at this tomorrow). The program now moves on to
check the efficiency of TOF's and Cerenkovs.
For this we have four small area scintillators (paddle's) behind TOFs
L0-L3. The start counter is on the beam left (and connected to L15). The
trigger is (start counter)*(any of paddles). In this way we should be
able to look at the efficiency for TOF's L0-L3 and LC0. These data can
also provide a useful trigger for the Wch. Note the trigger is done
entirely on the left sector and since about 5 pm we started taking data.
The blast field must be kept off.
The rate is a few Hz, corresponding to about 10k/hr. This is a bit on the
low side of rate estimates (that use only elastic scattering !!) and of
previous experience with these paddles. The first online analysis shows a
low efficiency number (80%). It also show however that the efficiency is
diluted by events hitting a neighbouring tof to that in front of a given
paddle
I have downloaded a ts2_ns.crl, since the common strobe (retime or) is only
an unnecessary complication at this point.
We should stay with this set up until we have a good understanding of it.
The plan for tonight
_ investigate and possibly optimize the paddle signal (HV? thresholds?).
In the logbook I've written down the "optimal voltages", but these
numbers may not be the best ones.
_ Make sure that all the TOF_1300 and TOF_1500 are written in the .sql
files in ~/commis/hv !!!
- Check all voltages, let's start from tof_1500 first.
- The tof efficiency should be high and one hr running is good enough to
use for analysis. Do "command line" analysis to understand things and
please do not think of writing super-scripts until you understand the
quality of your data.
_ Cerenkov issues (only LC0) are lower priority than TOF's. But of course
you can require start counter + tof + paddle to have fired (that applies
to tof's as well).
thanks,
-- 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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