Real data reconstruction A. De Caro (University and INFN of Salerno) CERN Building 29, December 9th, 2009ALICE TOF General meeting

Real data reconstruction

A. De Caro (University and INFN of Salerno)

CERN Building 29, December 9th, 2009

ALICE TOF General meeting

Data acquisition: preparation Definition status of readout channels (offline

condition database): on/off: Front-End Electronics database, coming from

Detector Control System dead/alive (pulser runs) noisy/not-noisy (noise runs)

Definition of reconstruction parameters (offline condition database) –from Montecarlo studies-: matching window, 2 track cut, etc.

Definition of alignment parameters (alignment database)

Definition of calibration parameters (calibration database)


A. De Caro 2 ALICE TOF General meeting

When a run acquisition ends… In case of physics runs:

a fast procedure calculates the first raw calibration parameters For cosmic runs and first collisions, these raw parameters

are the ones obtained with cosmic data calibration procedure (see R.Preghenella talk).

For future collisions, the raw calibration parameters will be the delays with respect to the expected time for primary pions at =1 (see C.Zampolli talk).

Then, these raw calibration parameters are written to the calibration database.

In case of noise/pulser runs: The status of all TOF channels is written in the

offline condition database.CERN Building 29, December 9th, 2009


Run reconstruction (1)It is a public and global work. It runs on the GRID (see F.Noferini talk).Raw data decoding

Each detector has developed its own code decoding, tested on the Montecarlo data and then tuned on the cosmic data.

At this point the TOF channel status is controlled in the offline condition database.

Tracking The ALICE tracking detectors (TPC -main-, ITS and

TRD) collect together their own clusters to form tracks



Run reconstruction (2) Track matching with the other detectors

Each external barrel detector -first of all TOF, then HMPID, PHOS and EMCal- has developed and provided its own code of detector-track matching.

At this point the calibration and the alignment parameters are taken into account.

The whole experiment code is public and available to all.

The TOF code as seen offline has just been checked by the ALICE Detector Performance Working Group Coordinatoron p-p events @ 900 GeV: “All this is getting more and more interesting !”



What did I do? And what am I doing? I checked/debugged:

the proper functioning of the noisy/not-noisy TOF channel definition;

that the reconstruction parameters used to reconstruct real events (i.e. cosmic and first p-p collision runs) were the right ones;

the TOF raw data decoding. Chiara and I are checking the fast online TOF

calibration procedure. I am checking the TOF-track matching algorithm. For my studies as well as for first data analysis, the

event display is a very useful analysis tool. I implemented the TOF event display code and I am still developing and updating it.



One of cosmic s triggered and seenby ALICE TOF detector



September 25th, 2009: injection test

TOF occupancy ~50%



November 21st, 2009: beam-gas collisionseen by ALICE TOF detector

zV is the interaction vertexdistance from the ALICE

reference system centre.It has been estimated to be

~6.2 m(only via TOF time

measurements)

zV









December 6th, 2009: first p-p collisionsseen by ALICE TOF detector also



December 6th, 2009: first p-p collisionsseen by ALICE TOF detector also



Documents

Real data reconstruction A. De Caro (University and INFN of Salerno) CERN Building 29, December 9th, 2009ALICE TOF General meeting