Diapositiva 1

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Status of EEE telescopes in Catania EEE Meeting,
CERN, 13 October 2007
F.Riggi Dept.of Physics and Astronomy INFN,
Catania
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Present status ? 1 Telescope (1) installed and
working at Dept.Physics INFN ? Preliminary set
of data collected from Telescope1 and analyzed ?
1 additional set of chambers (Telescope 2) just
arrived - waiting for some missing
electronics - first tests to be soon
carried out ? Involvement of high school teams
- Stages during testing phases - Data
analysis - General seminars and lectures
in the schools
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Installation of Telescope 1
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Telescope 2 under test
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Activity and tests carried out for Telescope
1 MRPC gas leakage Study of noise and cable
shielding MRPC single and coincidence rates at
different V Study of efficiency Test of GPS
antenna extension (40 m) Test of the VME trigger
card and DAQ LabView software
First set of data collected for a few days with
complete setup (trigger card, GPS,)
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• Software development for data analysis
• Reconstruction of hits, clusters and tracks
• Study of event properties (multiplicity,
  tracks,)
• Spatial resolution
• Angular distributions ( ? and F )
• Geometrical acceptance and corrections
• Tracking for multiple muons events (in progress)

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Typical strip multiplicity in each event (details
depend on thresholds) In most cases (90) only
1 strip In about 10 of cases 2 strips In
about 1 of cases gt 2 strips
Strip right
Strip left
Same data on log-scale
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Reconstruction of hits
A correct hit is defined by each strip with - a
signal above threshold at the two ends -
individual TDC values within correct limits -
time difference between -10 and 10 ns The
(x,y) coordinates of each hit are evaluated by
strip number and time difference at the two ends,
after folding in the TDC time resolution (100 ps)
and strip width (2.5 cm) with randomization.
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Hits multiplicity
Total number of hits
Event with 1 hit/chamber
1 chamber has 2 hits, mostly belonging to the
same track
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From hits to clusters
If 2 hits are very close (i.e. 2 close strips and
similar time differences) they likely belong to a
single track. The point (cluster) is then
evaluated as the spatial average of the two hits.
?7 cm
With a cut ?lt7 cm, about 2.5 of the events have
2 clusters in a chamber Only 0.1 of the events
have 2 clusters in each chamber (2 individual
tracks)
Distance between hits (?)
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Cluster multiplicity
Most of the events have only 1 cluster per
chamber. Events with 2 clusters in one or two
chambers are mostly recovered by track quality
criteria.
1 cluster /chamber
Events with gt1 cluster /chamber, mostly recovered
by track quality
?
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If there are more than 1 cluster per chamber
(maybe due to noise), all the possible tracks are
evaluated and the one with minimum distance from
points is selected. This allows in some cases to
recover up to 5 of the events.
Good track
Bad track
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Depending on the quality of the fit through the 3
points (cut on the quadratic sum of distances
from the fitted track, ?2), one may select good
tracks with a smaller efficiency, or the opposite
d1
?2 (d12 d22 d32)1/2
d2
d3
Efficiency () RMS-y
RMS-x No cut 100
4.23 5.91 ?2 lt 20 97.6
2.20 2.86 ?2 lt 10
95.3 1.51
2.33 ?2 lt 5 90.3
1.31 2.02
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Estimate of spatial resolution
UP
MIDDLE
BOTTOM
X_expected (x_bottom x_up)/2 X_found
X_expected Similar for Y
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Observed resolution has been corrected for
uncertainties also in BOTTOM and UP chambers. No
time-slewing correction applied yet.
By error propagation
RMS_x 2.3 cm (long-side) RMS_y 1.5 cm
(short-side)
?2 lt 10 Tracking Efficiency 95
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µ
From the fitted track, one may extract the
orientation (?, f) of the muon, and hence the
(uncorrected) angular distributions.
(?, f)
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Examples of uncorrected angular distributions
For nearly vertical muons the f-distribution is
isotropic, since the acceptance is const
For inclined muons the acceptance is strongly
dependent on f and the distribution becomes more
and more anisotropic
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Also the ?-distribution is strongly distorted by
the geometrical acceptance, since large angles
are detected with low probability.
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Geometrical acceptance
Track accepted
Track rejected

• Consider a point randomly chosen in MIDDLE
  chamber
• Generate a muon track according to realistic
  distributions
• Check if the track intersects both UP and BOTTOM
  chambers
• Evaluate geometrical acceptance by
  N_accepted/N_generated

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Geometrical acceptance matrix in (?,f)
f
?
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Acceptance along f
Generated muons
Accepted muons
Acceptance in f
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Acceptance along ?
Generated muons
Accepted muons
Acceptance in ?
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dN/d?
dN/d? sin? (dN/dO) sin? cos2?
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dN/df
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dN/df ?0-10
dN/df ?10-20
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dN/df ?20-30
Some anisotropy observed 2 main reasons under
investigation - East/West effect -
Muon absorption from building
North
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Effect of the building roofs and walls on muon
absorption
Roof
For vertical muons, about 1.5 m concrete!
P-3
P-2
P-1
PT
Telescope
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Conclusions A first telescope has been fully
tested and ready to take data Preliminary
analysis of a first set of local data carried
out Work in progress - Installation and
test of second telescope - Improvement of
data analysis