ALICE TOF FESTIVAL Offline tools and GRID scenario for the ALICE TOF detector A. De Caro (University of Salerno and INFN) CERN – Bdg.29, October 20 th

ALICE TOF FESTIVAL

Offline tools and GRID scenario for the ALICE TOF detector

A. De Caro(University of Salerno and INFN)

CERN – Bdg.29, October 20th 2008

ALICE TOF Offline Group activitiesALICE software, AliROOT:the detector geometry (materials and geometrical

distributions);the real MRPC features (t and time-over-threshold);the cluster finder;the reconstruction algorithm (matching);the particle identification (PID);the alignment procedure;the calibration (time slewing corrections and cable delays);the optimization of the ‘online’ - ‘offline’ connections

(databases);event display.

A lot has been already done… …but still a lot remains to do.

Nevertheless we are in good shape.A. De Caro 2ALICE TOF FESTIVALCERN-Bdg.29, October 20th 2008

OutlineTOF geometry: simulation detailsTOF MRPCs: simulation of the test beam

resultsTOF clustering: new algorithm implementationTOF particle identificationFirst cosmic through tracking detectors

matched with TOF detectorFirst alignment studiesSome of the ALICE TOF Offline Group

successes

A. De Caro 3ALICE TOF FESTIVALCERN-Bdg.29, October 20th 2008

Materials, shapes and their geometrical distributions in the ALICE reference frame

SM0

SM1

SM2

SM3SM4

SM5

SM6

SM7

SM8

SM9 SM17


SM0

SM1

SM2SM3

SM4SM5

SM6

SM7

SM8

SM9

SM10

SM11

SM12SM13 SM14

SM15

SM16

SM17

TOF SMs as described in the AliROOT framework


TOF SM: services detail

real simulation


Finger to cool NINO ASIC

real

simulation

TOF SM: front-end electronics detail


Description of the real MRPC features:detection efficiency

(time resolution and time-over-threshold)as a function of the hit pad position

Pads possibly

activated by

electrical induction

effects

Pad hit

by a particle

XZ

Y


TOF MRPC strip: detection efficiency

CERN-Bdg.29, October 20th 2008 ALICE TOF FESTIVAL A. De Caro 11

3 1 54 2 6



3 1 54 2 6



3 1 54 2 6



3 1 54 2 6



3 1 54 2 6



3 1 54 2 6

TOF MRPC strip: detection efficiency3 1 54 2 6


Standard clustering algorithm: one cluster per each fired pad.New clustering algorithm: one cluster per each set of

neighbouring fired pads with comparable time measurements(according to the time resolution).

Cluster time:currently, the time weighted average (per tot);

with calibration parameters, better estimation (NIM A532, 611-621, 2004).

Similar remarks for the cluster position.

con segnale

senza segnale

firednot fired


Comparison between the two clustering algorithms

In blue: standard TOF cluster

In red: new TOF cluster

In green: TOF pad interested by signal

TOF strips as tracking detectors

In yellow: standard TOF cluster fit

In violet: new TOF cluster fit

D. De Gruttola, Phd thesis, Salerno May 9th 2008

TOF strip in test


Detail on the pad interested by signal,

7th strip, the one in test.

The violet line crosses the strip in test

while the yellow one does not.

The chosen order parameter is the distance

between the impact point

of the reconstructed track to the hit pad centre.

This order parameter is minimum

in case of new TOF cluster fit.

In blue: standard TOF cluster

In red: new TOF cluster

In green: TOF pad interested by signal

In yellow: standard TOF cluster fit

In violet: new TOF cluster fit

Comparison between the two clustering algorithms

D. De Gruttola, Phd thesis, Salerno May 9th 2008A. De Caro 21ALICE TOF FESTIVALCERN-Bdg.29, October 20th 2008

ALICE TOF detector performances:reconstructed mass vs momentum

and PID efficiency and contaminationin p-p and central Pb-Pb collisions

Mass vs momentum (PPR 2nd vol.)


TOF PID efficiency and contamination (PPR 2nd vol.)


Some results obtained with the analysis of the data taken during the cosmic runs (12/07-

09/08)with/without L3 magnetic field.

Good chance to test the code with real data.

Cosmic muon reconstructed in ALICE detector (B=0 T)

t1

t2

t1<t2

Muon direction

TPC clustersTRD clustersTOF clustersReconstructed track


Prospective view


t1

t2

t1<t2Muon direction

B = - |B| k -

Cosmic muon reconstructed in ALICE detector (B=0.5 T)


A. De Caro 29

-

Prospective view


To check the functionalities of the alignment algorithm with real events

Distance-approach (-z view)First alignment step for

the TOF detector: along the beam direction, i.e. the z axis.

Distance-approach: the distance between the impact point of the reconstructed track on the TOF strip and the closer TOF cluster centre (schematically shown here).

The z component of the distance-approach is the parameter used to align TOF SMs along z axis.

=371 cm

Reconstructed track





TPC: field cage internal wall


TPC: field cage internal wall

Caused by

a not corrected calibration

for the drift velocity

(TPC people confirmed).

Several successes obtained by the TOF Offline Group. Some of them publicly acknowledged

by the ALICE Offline Group (green light for the TOF detector)

F.Carminati @ May 2007 Technical Boardhttp://indico.cern.ch/materialDisplay.py?contribId=14&materialId=slides&confId=7361

Wri

tten

cod

e / c

ode

to b

e w

ritt

en [

%]

TOF

Average

81.5%


Shuttle algorithm: online <-> offline

Responsible: C. Zampolli

http://aliceinfo.cern.ch/Offline/Activities/Shuttle.html


Raw data implementation statushttp://aliceinfo.cern.ch/Offline/Activities/Raw-Data.html

TOF



Documents

ALICE TOF FESTIVAL Offline tools and GRID scenario for the ALICE TOF detector A. De Caro (University of Salerno and INFN) CERN – Bdg.29, October 20 th