PHOS offline status ALICE offline meeting 9 13

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PHOS off-line status ALICE off-line meeting 9 -13 September 2002 Yuri Kharlov Subatech/IN 2

PHOS off-line status ALICE off-line meeting 9 -13 September 2002 Yuri Kharlov Subatech/IN 2 P 3 & IHEP/Protvino (for the PHOS off-line team)

PHOS geometry • • • Acceptance: 0. 12, 100 Construction: 5 modules EMC+CPV EMC:

PHOS geometry • • • Acceptance: 0. 12, 100 Construction: 5 modules EMC+CPV EMC: 64 56 cells each module EMC cell: 2. 2 18 cm 3 Pb. WO 4 CPV: 128 56 cathode pads, anode wires with 5. 56 mm pitch 10/2/2020 2

PHOS geometry in ALIROOT 10/2/2020 3

PHOS geometry in ALIROOT 10/2/2020 3

PHOS within ALICE 10/2/2020 4

PHOS within ALICE 10/2/2020 4

Code development (as of September 2002) • We work at Linux RH 7. 2,

Code development (as of September 2002) • We work at Linux RH 7. 2, RH 7. 3 • We use gcc 3. 2 • We use root 3. 03 -08 • We use always CVS HEAD of Ali. Root Simulation • Ali. PHOSv 0: real geometry, passive material (no hits) • Ali. PHOSv 1: as Ali. PHOSv 0 + hits hit: x, y, z, Eloss, Id, primary (one hit per primary per cell) • Ali. PHOSv. Impact: as Ali. PHOSv 1 + impacts impact: x, y, z, p at the detector ’s upper surface • Ali. PHOSv. Fast: fast simulation (not really used) 10/2/2020 5

Reconstruction • Whole reconstruction chain from Hits to Rec. Particles works in split and

Reconstruction • Whole reconstruction chain from Hits to Rec. Particles works in split and non-split mode • Wrapper class for the reconstruction chain: Ali. PHOSReconstructioner • All tasks are created analogously: Ali. PHOS<task>(simulated file, branch name, split/no-split) 10/2/2020 6

Reconstruction user case: non-split mode After simulation: galice. root with g. Alice, geometry, Tree.

Reconstruction user case: non-split mode After simulation: galice. root with g. Alice, geometry, Tree. E, Tree. H è s=new Ali. PHOSSDigitizer(“galice. root”) s->Exec(“deb all tim”) è d=new Ali. PHOSDigitizer(“galice. root”) d->Exec(“deb all tim”) è c=new ALi. PHOSClusterizerv 1(“galice. root”) c->Exec(“deb all tim”) è t=new Ali. PHOSTrack. Segment. Makerv 1(“galice. root”) t->Exec(“deb all tim”) è p=new Ali. PHOSPIDv 1(“galice. root”) p->Exec(“deb all tim”) After reconstruction: the same galice. root with Tree. S, Tree. D, Tree. R filled 10/2/2020 7

Reconstruction user case: split mode After simulation: galice. root with g. Alice, geometry, Tree.

Reconstruction user case: split mode After simulation: galice. root with g. Alice, geometry, Tree. E, Tree. H è s=new Ali. PHOSSDigitizer(“galice. root”, ” 1”, k. TRUE) s->Exec(deb all tim”) Tree. S is written to PHOS. SDigits. 1. root è d=new Ali. PHOSDigitizer(“galice. root”, ” 1”, k. TRUE) d->Exec(deb all tim”) Tree. D is written to PHOS. Digits. 1. root è c=new Ali. PHOSClusterizer(“galice. root”, ” 1”, k. TRUE) c->Exec(deb all tim”) Tree. R with Rec. Points is written to PHOS. Rec. Data. 1. root è t=new Ali. PHOSTrack. Segment. Makerv 1(“galice. root”, ” 1”, k. TRUE) t->Exec(deb all tim”) Tree. R with Track. Segments is written to PHOS. Red. Data. 1. root è p=new Ali. PHOSPIDv 1(“galice. root”, ” 1”, k. TRUE) p->Exec(deb all tim”) Tree. R with Rec. Particles is written to PHOS. Red. Data. 1. root 10/2/2020 No g. Alice, Tree. E, Tree. K, Tree. H, geometry is written to the split files 8

Reconstruction (continued) • Reconstruction can be performed either by a script calling tasks one-by-one,

Reconstruction (continued) • Reconstruction can be performed either by a script calling tasks one-by-one, or • Reconstruction wrapper: all-in-one r=new Ali. PHOSReconstructioner(file, branch, split) r->Execute. Task(“deb”) • PHOS reconstruction is not compatible with Ali. Run. Digitizer in a split mode because g. Alice is missing in split files • Mixing events at SDigits level: in Ali. PHOSDigitizer: : Mix. With(another file) 10/2/2020 9

EMC performance (1) Energy resolution Position resolution Simulation reproduces measurements 10/2/2020 10

EMC performance (1) Energy resolution Position resolution Simulation reproduces measurements 10/2/2020 10

EMC performance (2) Rec. point shift due to inidence angle 10/2/2020 Effective shower maximum

EMC performance (2) Rec. point shift due to inidence angle 10/2/2020 Effective shower maximum depth vs E 11

EMC performance (3) 10/2/2020 12

EMC performance (3) 10/2/2020 12

CPV performance (1) x-resolution z-resolution EMC-CPV distance Simulation reproduces measurements 10/2/2020 13

CPV performance (1) x-resolution z-resolution EMC-CPV distance Simulation reproduces measurements 10/2/2020 13

CPV performace (2) Matching probability of charged particles with EMC rec. point 90% of

CPV performace (2) Matching probability of charged particles with EMC rec. point 90% of e- give matching EMC-CPV rec. points 10/2/2020 10% of are lost having the minimal material (with holes in TRD and TOF) 14

Particle identification in PHOS (1) PHOS identifies particles by: • time-of-flight • distance between

Particle identification in PHOS (1) PHOS identifies particles by: • time-of-flight • distance between CPV and EMC rec. points • shower shape in EMC (2 approaches): - at very high energies neural networks can be used - at any energies principal components analysis can be applied 10/2/2020 15

Particle identification in PHOS (2) Photon/ 0 identification with a Neural Network • Reconstructed

Particle identification in PHOS (2) Photon/ 0 identification with a Neural Network • Reconstructed particles are defined by E, 1, 2, M 10, M 30, M 40, M 04, • NN response S (0, 1) classifies clusters. • ( , ) varies from 90% to 20% at E=20 -120 Ge. V • ( , 0) is 1 -3% in this range 10/2/2020 16

Particle identification in PHOS (3) Photon identification with the Principal Components Analysis Rec. point

Particle identification in PHOS (3) Photon identification with the Principal Components Analysis Rec. point is characterized by the following parameters: • Lateral dispersion • Shower ellipse axes • Sphericity • Core energy • Largest energy fraction in one crystal TPrincipal reduces all parameters to 2 significant ones 10/2/2020 17

Our plans and needs • Global tracking: reconstructed tracks in ITS+TPC can be propagated

Our plans and needs • Global tracking: reconstructed tracks in ITS+TPC can be propagated to PHOS to improve CPV-EMC matching and track segment making • finish PID • Adopt aliroot for bea-test data analysis • Implement data bases for dead modules and calibration coefficients 10/2/2020 18