28.09.2007 ECAL PID 1

Particle identification in ECAL

Yuri Kharlov, Alexander ArtamonovIHEP, Protvino

CBM collaboration meeting28.09.2007

28.09.2007 ECAL PID 2

PID methods applicable for ECAL

The aim of ECAL PID is to discriminate and e from anything else

• Charged track matching– Reject (for ) or identify (for e) ECAL clusters produced by

charged tracks

• Flight time measurement– Reject ECAL clusters produced by slow particles (mainly heavy

hadrons)

• Transverse shower shape– Discriminate electromagnetic and hadronic showers

• Longitudinal shower profile– Discriminate electromagnetic and hadronic showers

28.09.2007 ECAL PID 3

Flight time from target to ECAL (12 m)

Neutral hadrons contribute to photon spectrum mainly at E<2 GeV

Significant background is expected from antineutrons at 1.8 GeV

Time resolution t=1 ns is sufficient for rejection of K0 and neutrons

28.09.2007 ECAL PID 4

Longitudinal profile of electromagnetic shower (PDG)

28.09.2007 ECAL PID 5

Prototype of “Two-Sections” ECAL Module

Two channel PMT based on PM FEU-

115M dynode system

110

450

20X0 = 10X0 + 10X0

Total radiation length = 20Xo.Number of layers = 85Lead plate thickness = 1.3 mmScintillator plate thickness = 4.0 mmScintillator – Polystyrene + 1.5%PT + 0.05% POPOPWave Length Shifting Fibers – Y11

Lucite prism for uniform light

mixing

Light from the first half of calorimeter (preshower) was collected to one anode and light from the second half to another.

V.Brekhovskikh, V.Rykalin 21 September 2006

28.09.2007 ECAL PID 6

2-segment module designSeparate light collection to 2-channel PMT

V.Brekhovskikh, V.Rykalin 21 September 2006

28.09.2007 ECAL PID 7

All

calo

rim

ete

r

Preshower

Accepted electrons (84%)

Rejected pions (93%)

Beam measurements of 2-segment module

V.Brekhovskikh, V.Rykalin 21 September 2006

28.09.2007 ECAL PID 8

Simulation model

• 1 module with 160 layers (Pb 0.7 mm + Sci 1.0 mm)

• Total radiation length: 20X0.

• 20 longitudinal segments, each of 8 layers

• Various combinations of energies deposited in different segments allow to optimize longitudinal segmentation

28.09.2007 ECAL PID 9

Edet vs Segment number: 5 GeV

Photons Hadrons

28.09.2007 ECAL PID 10

Edet vs Segment number : 10 GeV

Photons Hadrons

28.09.2007 ECAL PID 11

Edet vs Segment number : 15 GeV

Photons Hadrons

28.09.2007 ECAL PID 12

Longitudinal profile: Photons

5 GeV 10 GeV

28.09.2007 ECAL PID 13

Longitudinal profile: Hadrons

5 GeV 10 GeV

28.09.2007 ECAL PID 14

Longitudinal profile: Muons

5 GeV 10 GeV

28.09.2007 ECAL PID 15

E1/E2, 5 GeV (1X0+19X0)

28.09.2007 ECAL PID 16

E1/E2, 5 GeV (2X0+18X0)

28.09.2007 ECAL PID 17

E1/E2, 5 GeV (3X0+17X0)

28.09.2007 ECAL PID 18

E1/E2, 5 GeV (4X0+16X0)

28.09.2007 ECAL PID 19

Identification probabilities (1X0+19X0)

E1/E2 cut

0.005 0.010 0.015 0.020 0.025 0.030

5 GeV 0.725 0.872 0.938 0.962 0.969 0.972

- 0.200 0.331 0.381 0.405 0.424 0.447

10 GeV 0.857 0.957 0.968 0.970 0.970 0.970

- 0.250 0.357 0.405 0.439 0.462 0.482

15 GeV 0.925 0.970 0.972 0.972 0.972 0.972

- 0.281 0.381 0.425 0.451 0.474 0.498

S/B=3.5

28.09.2007 ECAL PID 20

Identification probabilities (2X0+18X0)

E1/E2 cut

0.010 0.030 0.035 0.045 0.055 0.065

5 GeV 0.418 0.563 0.734 0.821 0.882 0.920

- 0.132 0.287 0.366 0.389 0.406 0.426

10 GeV 0.525 0.716 0.886 0.940 0.960 0.967

- 0.196 0.318 0.394 0.421 0.442 0.463

15 GeV 0.608 0.818 0.948 0.966 0.970 0.972

- 0.229 0.346 0.414 0.436 0.455 0.476

S/B=3

28.09.2007 ECAL PID 21

Identification probabilities (3X0+17X0)E1/E2

cut0.05 0.10 0.15 0.20 0.25

5 GeV 0.432 0.689 0.865 0.938 0.965

- 0.330 0.395 0.550 0.774 0.840

10 GeV 0.582 0.867 0.955 0.969 0.970

- 0.359 0.436 0.596 0.835 0.907

15 GeV 0.692 0.939 0.970 0.972 0.972

- 0.381 0.445 0.612 0.857 0.924

S/B=2

28.09.2007 ECAL PID 22

Identification probabilities (4X0+16X0)

E1/E2 cut

0.10 0.20 0.30 0.40 0.50

5 GeV 0.334 0.613 0.824 0.925 0.960

- 0.341 0.462 0.775 0.835 0.853

10 GeV 0.466 0.810 0.943 0.967 0.970

- 0.380 0.517 0.849 0.916 0.935

15 GeV 0.576 0.906 0.967 0.972 0.972

- 0.394 0.530 0.866 0.933 0.952

S/B=1.5

28.09.2007 ECAL PID 23

To do

• 3-segment module: the optimal segmentation to be found• Realistic momentum distribution of incoming particles• Realistic particle multiplicity to be studied• Track-ECAL matching and optimization of the matching

distance for charged particle rejection• Simulation of realistic TOF measurement in ECAL and

optimization of ECAL-TOF cut for heavy hadron rejection• Photon identification efficiency and hadron contamination

of the photon spectrum in central HI collisions