tof offline and calibration a. de caro (university and infn of salerno)

TOF offline and calibration

A. De Caro (University and INFN of Salerno)

Status of the TOF code Updated:

Calibration parameters (P.Antonioli, S.Arcelli, ADC, R.Preghenella, C.Zampolli);

TOF channel hardware status definition (A.Alici, P.Antonioli, ADC);

Data Quality Monitoring histograms definition (F.Bellini); Alignment task (B.Guerzoni).

To be updated: Calculate alignment parameters on new reconstruction data; Check the currently used TOF calibration parameters with the

aligned detector; TOF trigger description (A.Silenzi); Event time calculation in case of incomplete information coming

from T0 detector (see D.Caffarri’s talk); TOF cluster finder algorithm (D.De Gruttola); Quality assurance histograms definition; TOF-track matching: associate all matchable TOF clusters to

each reconstructed track, together the only one matched according to DCA.

CERN Building 29, March 24th 2010

ALICE TOF General meeting

A. De Caro 2

Status of the TOF code Updated:

Calibration parameters (P.Antonioli, S.Arcelli, ADC, R.Preghenella, C.Zampolli);

TOF channel hardware status definition (A.Alici, P.Antonioli, ADC);

Data Quality Monitoring histograms definition (F.Bellini); Alignment task (B.Guerzoni).

To be updated: Calculate alignment parameters on new reconstruction data; Check the currently used TOF calibration parameters with the

aligned detector; TOF trigger description (A.Silenzi); Event time calculation in case of incomplete information coming

from T0 detector (see D.Caffarri’s talk); TOF cluster finder algorithm (D.De Gruttola); Quality assurance histograms definition; TOF-track matching: associate all matchable TOF clusters to

each reconstructed track, together the only one matched according to DCA.



A. De Caro 3

What did we change in the TOF code……from the first ALICE p-p collision data

(December 2009) till now? As a first look of p-p collision data, it was to be

checked: Offset(s) of TOF time measurements ~1.6s (to be

noted that the expected time-of-flight for a primary particle to reach the ALICE-TOF detector at ~378cm from the interaction point is ~16ns);

TOF channel hardware status: description to be completed.


A. De Caro 4 ALICE TOF General meeting

Offset in TOF time measurements



A. De Caro 5

Correction of TOF measurementsat analysis level A couple of TOF analysis classes tuned on

2009 December p-p collision data (prepared by F.Noferini) have been published.

With these classes at analysis level, all ALICE components can: recalculate the TOF time measurement associated

to a reconstructed track, estimate the event-time with the combinatorial

algorithm of the TOF measurements, recalculate the TOF particle identification (PID)

probabilities, useful for PID with bayesian approach.



6

Correction of TOF measurementsat reconstruction level Till the second-last reconstruction step

tTOFESD = tTOF

raw+

- tonlineCalibration +

+ BCTDC

where: tTOF

ESD, TOF time associated to each reconstructed track matched to a TOF sensitive element;

tTOFraw, measured TOF time (available in TOF raw data);

tonlineCalibration, TOF calibration offset extrapolated from the calibration parameters calculated on cosmic and 2009 December p-p collisions data (available in the offline database, called OCDB);

BCTDC, TDC bunch crossing ID (available in TOF raw data).



A. De Caro 7

Correction of TOF measurementsat reconstruction level (cont.)



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A. De Caro 10

TOF channel hardware status



A. De Caro 11

TOF channel hardware status A TOF channel can be off for three reasons:

its read-out channel is disabled (RO status); its associated FEA is not powered (LV status); its associated MRPC strip is not powered (HV status).

Per each of these cases, the Detector Control System sends bit maps to the offline: RO.and.LV status map read at start of run-SOR:

ready to propagate it in the OCDB; LV and HV status maps read at SOR, end of run-

EOR-, every 10minutes and when there are changes: almost ready; fixed technical problem in the code; numbering conversion from online to offline to be

controlled: work in progress.



A. De Caro 12

TOF channel offline hardware statusKnown 2009 December TOF hardware configuration



A. De Caro 13

~10% not active TOF channels

Thanks to Gilda, Silvia and Francesca

See A.Alici’s talk for current TOF configuration.

Let me remind TOF-track matching definition To be taken into account:

Material budget; Particle decays; TOF acceptance (PHOS hole, mechanical holes

between TOF elements); Noisy channels and active readout channels; High voltage status for TOF detector

elements (~1600 MRPC strips); Low voltage status for TOF front-end

electronics (~570 FEAC cards).



A. De Caro 14

Information not available at offline level during 2009 December runs



A. De Caro 15

€

εmatching =NTOF

N reco

€

NTOF = TOF matched tracks(*)

N reco = reconstructed tracks(*) in |η |< 0.9(*)Track selection : standard cuts



A. De Caro 16


Real data: run 104852MC data: LHC09d9

ADC @ 2009 December PWG1 meeting

€

εmatching =NTOF

N reco

€





A. De Caro 17


Real data: run 104852MC data: LHC09d9

ADC @ 2009 December PWG1 meeting

R.Preghenella study

Tuned MC means that we removed the noisy or not active TOF channels (with HV or LV or RO problems) at analysis level.

€

εmatching =NTOF

N reco

€



Thanks for your attention

tof offline and calibration a. de caro (university and infn of salerno)

Documents

tof code

tof offline

alicetof detector

correction of tof measurements

matchable tof clusters

alice tof general meetinga

measured tof ti

couple of tof analysis