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Minutes of the Physics Commissioning Meeting, July 7

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Thorsten Oest

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Jul 8, 1999, 3:00:00 AM7/8/99

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Minutes of the Physics Commissioning Meeting, July 7
====================================================

-- J/psi search in magnet on data Kendall Reeves

Code developed for the SLt farm has been used to search offline
for a J/psi in the exp01 data (magnet on). Two ECAL clusters
(Pt1(cell)>1.1 GeV, Pt2(cluster)>0.7 GeV) were taken as
candidates for electrons from the J/psi. For each lepton
candidate a region of interest in the RICH can be determined
where to look for a beta=1 ring. Only very clean rings
with a signal/sqrt(background)>7 were accepted.
Rings for both lepton candidates were required. Additional cuts
are: -- number of photons per ring < 60 (against conversions)
-- 0.5 < E/p < 1.35 (to enrich electrons)
-- delta y of the two ECAL/RICH tracks at target position
< 0.25 cm

2.4 million events were analysed. A 5 sigma enhancement was found
at a mass of 2.94 GeV with a width of 25 MeV. The number of
events observed (100+-25) is in rough agreement with an estimate
by Mike Medinnis. Following points are not yet understood and does
not support the hypothesis for a J/psi observation:
-- the mass shift
-- the width; from the momentum resolution a width on the order of
> 100 MeV is expected
-- bremsstrahlung recovery is not included
-- the cut on delta y < 0.25 mm is very hard and has to be justified
MC studies are under way to understand these points in more detail.

-- online reconstruction preparations for August

o farm status Andreas Gellrich
There farm will have 30 CPUs in August. This restricts the
processing time per event to roughly 1 second. The logging
bandwidth allows for a 20-50 Hz logging rate (assuming that
the event size is 100kB).

o alignment status Thorsten Oest
VDS/ECAL/RICH/target target alignment will be done off line in
August. It is expected that this takes two days and the constants
are valid for a period larger than a week. The online
implementation is planed for mid of August.
No OTR/ITR and TRD alignment will be available at the beginning
of August. Muon and hight-pt alignment is not critical.

o discussion on online reconstruction code
To allow for tests it is necessary to fix the code for August
around July 11. The following code will enter the online
reconstruction (so far):
ARTE version: ARTE-02-08-r2
VDS: Holmes
ECAL: CARE
RICH: RISE
MUON: MURECA
OTR: ---
ITR: ---
TRD: probably nothing (no statement from the subgroup)
hight-pt: probably nothing (no statement from the subgroup)
track segment matching: MARPLE

There is still a problem with the RICH reconstruction which takes
more than a second. This has to be solved.

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| Thorsten Oest Phone : [49] (40) 8998 3008 |
| Uni HH / HERA-B Fax : [49] (40) 8998 4018 |
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