Looking into the calibration code, I saw that one of the cuts impossed
to all muon data that are used for calibrations is that the track crosses
the plane at 345cm from ground (bottom=88, center=521, therefore it is
roughly the middle plane between bottom and center faces.)
There is also another cut that imposses that all pathlengths (from 1st
to 2nd AND from 2nd to 3rd boxes) should be more than 200cm.
These two cuts practically eliminate all muon hits involving the 8th
and 9th vertical counters. Typically, out of ~200 muons survive <10 (per week).
Another factor that contributes to this reduction of hits for the 8th and
9th vertical counters (a total of 24 boxes) is that many times the MAKETRK
code that prepares the .TRK files is missing the streamer tube information
for these hits - in fact it finds that the track, as reconstructed by the
positions obtained from the streamer tubes, does not intersect these counters
about 25% of the time.
Given that the MAKETRK code runs on VXMACB using an old version of CALMOD
(I'm not sure which updates on the GEOMETRY section have been effected there),
could it be that it is just using wrong geometry information ? BTW, I also
saw a very similar set of cuts as those described above (crossing the 345cm
plane and pathlengths>200cm) in the MAKETRK code; fortunately, it only
flags the hits but they are nevertheless saved on the .TRK file.
I feel that these cuts impose not only a severe cut on muon hits which
renders calibration of Attivo vertical counters (and in particular the 8th
and 9th) virtually impossible, but also introduce a systematic error (bias)
on the types of muons used for calibrations (imposes different solid angles
for acceptance for different counters, depending on geometry.)
Can somebody look into this and give me feedback as to whether I need
to make the corresponding changes to the calibration/MAKETRK code ? Is this
345cm plane cut a leftover of the lower MACRO only period ?
Finally, it might be useful to know which of these cuts exist also
in the monte-carlos.
For more information regarding the above, please drop me a line. I am
preparing a long e-mail report, that already has a draft version available.
I'll be glad to e-mail it to whoever is interested.
A presto,
Ioannis Katsavounidis