1Nantes — 2008, July 15-17

Analysis of results from

EmCal beam test at CERN PS (and SPS) energies

P. La Rocca & F. P. La Rocca & F. RiggiRiggi University & INFN University & INFN CataniaCatania

2Nantes — 2008, July 15-17

Outlook

• General considerations (cuts, selections,…)• Temperature analysis• Temperature – Amplitude correlation• Inter-calibration at 3 GeV/c• Energy resolution at 3 GeV/c• Preliminary analysis of all PS and SPS energy runs

3Nantes — 2008, July 15-17

Beamtest Set-up

64 towers MWPCScintillators

beamČerenkov

(at PS)

PS BEAM: electrons and hadrons (0.5 – 6.5 GeV/c)(Čerencov detector to discriminate)

Electron and beam (pions) runs at 3 GeV/c in all towers. Electron and beam momentum scans 0.5, 1, 2, 3, 5 and 6.5 GeV/c at 6 different

locations (centers and boundaries of some modules). Phi angle scans at 9°, 6° and 3° (for electrons and pions) Large Z configuration Cosmic runs

4Nantes — 2008, July 15-17

SPSBEAM: electrons (5-80 GeV/c) / hadrons (20-100 GeV/c)

High statistics electron runs at 80 GeV/c in all towers for relative calibrations.

100 GeV hadrons for relative calibration comparison using the mip peak. Electron momentum scans 5, 10, 20, 40, 60, 80, and 100 GeV/c at the

centers of several towers, and at 2 cm steps crossing module boundaries in X and Y.

Hadron data at 20, 40, 60, 80, and 100 GeV/c to measure the hadron energy deposition distributions, and to measure hadron shower shapes.

Hadron measurements at 100 GeV/c at module boundaries in X and Y to investigate hadron shower shape dependence on position.

Beamtest Set-up

5Nantes — 2008, July 15-17

Working conditions 1/2P

SLED signals nSig > 50 17 < tmaxSig < 19

BEAM signals nSig < 50 11 < tmaxSig < 13.5

6Nantes — 2008, July 15-17

Working conditions

2/2SPS

LED signals nSig > 100 16 < tmaxSig < 19

BEAM signals nSig < 100 5 < tmaxSig < 10

7Nantes — 2008, July 15-17

Temperature analysis

8Nantes — 2008, July 15-17

APD temperature dependence- In principle gain dependence on temperature quite similar for all APDs

(see Giuseppe’s talk)

- Temperature correction: LED(itower , jrun) / LED(itower , Ref)

Problems: Jumps in the signal issued by the LED pulser (discussed by Rachid) No correlation in some towers

LED correction applied only on few runs (first PS period) to study its effect on the energy resolution

9Nantes — 2008, July 15-17

Tower Inter-calibration

E(I) = A * c_I *AmpSig(I) * LED(I,J) / LED(I,Ref)

Energy in tower I (run J):

Temperature Correction

Inter-calibration scale factors

- 1st method: inter-calibration by MIPs

- 2nd method: inter-calibration by minimization

Both methods applied to 3 GeV runs (1015 - 1205)

Absolute energy scale factor

10Nantes — 2008, July 15-17

MIP SELECTION ->Isolation cut

(cut less efficient for towers in the boarders)

Background due to hadronic shower produced by pions

After isolation cut

PS

amp_around = 0

SPS

Inter-calibration by MIPs 1/3

11Nantes — 2008, July 15-17

Inter-calibration by MIPs 2/3

3x3 cluster energy around tower (3,4)

without calibrationwith calibration

REF

12Nantes — 2008, July 15-17

Inter-calibration by MIPs 3/3

Energy resolution for each individual tower- Values spanning from 7.2% to 11.7 % - Weighted mean 8.6%

13Nantes — 2008, July 15-17

Minimization algorithm 1/2

Calibration factors i calculated by the minimization of the quantity:

where index i runs over the towers, index j over all calibration events

A system 64x64 must be solved!

14Nantes — 2008, July 15-17

Minimization algorithm 2/2

Energy resolution for each individual tower (4x4 inner towers)- Values spanning from 7.1% to 10.8 % - Weighted mean 8.1%

The minimization algorithm seems to give slightly better results

15Nantes — 2008, July 15-17

Tower Inter-calibration & energy resolution at η 0

Analysis repeated for other energies (longer runs): - MIP Inter-calibration done only for central towers (2 < row < 4 && 3 < col < 5)- for the estimation of the energy resolution selected only those events with the maximum amplitude in row = 3 and col = 4

Momentum (GeV/c) El. runs

0.5 1393

1 1397,1398

2 1464

3 1424

5 1423

6.5 1422

Momentum (GeV/c) El. runs

10 410, 412

20 407, 408, 409

40 405, 406

60 403, 404

80 270 - 275

100 397 - 400

SPS PS

16Nantes — 2008, July 15-17

Energy resolution at η 0 1/3

0.5 GeV/c

1 GeV/c

2 GeV/c

3 GeV/c

5 GeV/c

6.5 GeV/c

17Nantes — 2008, July 15-17

Energy resolution at η 0 2/3

10 GeV/c

20 GeV/c

40 GeV/c

60 GeV/c

80 GeV/c

100 GeV/c

18Nantes — 2008, July 15-17

Energy resolution at η 0 3/3

19Nantes — 2008, July 15-17

Conclusions

• Full analysis at 3 GeV/c (Temperature, calibration, energy resolution…)

• Analysis at all PS and SPS energies for central towers