A. De Caro
for the ALICE TOF Offline Group
(University of Salerno and INFN)
Some results obtained with the analysis of the data
taken during the cosmic runs (12/07-09/08)
with/without L3 magnetic field.
Analysis of the cosmic run data
 During last summer, we worked to the analysis of the
data taken during the cosmic runs and we updated the
TOF code according to this analysis results.
 After:
 noise study,
 correction of time measurements per cable delays,
 correction of time measurements per some found offsets;
 correction of the maximum distance-approach of a
reconstructed tracks to a matchable TOF hit pad (one of
the recoParams),
we successful reconstructed some events.
October 21th 2008
ALICE Offline Week
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Cosmic muon reconstructed in ALICE detector (B=0 T)
TPC clusters
TRD clusters
TOF clusters
Reconstructed track
t1<t2
t1
Muon direction
t2
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Prospective view
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Cosmic muon reconstructed in ALICE detector (B=0.5 T)
t1<t2
Muon direction
t1
t2
-
B = - |B| k
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Prospective view
-
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To check the functionalities of the alignment algorithm
with real events
Distance-approach (r-z view)
 First alignment step for the
TOF detector: along the
beam direction (z axis).
 Distance-approach: the
distance between the
impact point of the
reconstructed track on the
TOF strip and the centre of
the closer TOF cluster
(schematically shown
here).
r=371 cm
 The z component of the
distance-approach is the
parameter used to align
TOF SMs along z axis.
October 21th 2008
Reconstructed track
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Distance-approach distributions (B=0 T) -1-
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Distance-approach distributions (B=0 T) -2-
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Distance-approach distributions (B=0 T):
aligned geometry -1-
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Distance-approach distributions (B=0 T):
aligned geometry -2-
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Distance-approach vs strip per TOF SM (B=0 T)
TPC: field cage internal wall
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Distance-approach vs strip per TOF SM (B=0.5 T)
TPC: field cage internal wall
Caused by
a not corrected calibration
for the drift velocity
(TPC people confirmed).
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I would like to understand why I didn’t receive answer…
Email on 12/09/08 @ Marian.Ivanov:
do you know how often it is necessary to update the TPC reco parameters (gain factor, as example)?
Email on 07/10/08 @ Marian.Ivanov
and email on 08/10/08 @ Marek.Kowalski (who forwarded this email to Marian.Ivanov):
…I noted also that
there was a 'strange' trend for DeltaZ paramenter,
that is the distance along the beam direction between the reconstructed track
and the matched TOF sensitive element.
In particular, I can see the following trend:
| DeltaZ | ~ a * z + b
where a and b parameters assume different values for z<0 and z>0
(practically, at z=0, there is an offset between the two lines found for z>0 and z<0).
Maybe you find similar results...
For this I am sending you this email.
I hope you can give me more details about.
October 21th 2008
ALICE Offline Week
A. De Caro
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Geometry overlaps in the following cases:
OK
Ideal misalignment
To be checked
Residual misalignment
Full misalignment
See next slide
TOF survey alignment object:
we have one of them only recently inserted in the DCDB
but we have to check the code with this object.
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FSTR/FTLA and FSTR/FLTC extrusions
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FSTR/FTLA and FSTR/FLTC extrusions
FTSR25
October 21th 2008
FTSR29
FTSR63
ALICE Offline Week
FTSR67
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ESD track selection conditions
0cm<y0<65cm
10°<f<30°
-65cm<y0<0cm
10°<f<30°
-65cm<y0<0cm
150°<f<180°
0cm<y0<65cm
150°<f<180°
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TOFforTRD trigger
SM7&&SM17
SM1&&SM9
SM8&&SM16
SM0&&SM10
E. Scapparone, Physics Forum, 2nd July 2008
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