1. Material in front of the calorimeter: Analysis from the data using the sub-detectors response L.Basara, A.Fiasson, C.Goy, M.Paniccia, S.Rosier LAPP-Annecy
Courtesy of the ECAL group, TOF group,
Bruna and Cecilia, V.Choutko , V.Plyaskine, K.Lübelsmeier and L.Derome
Updated version of EPreJ Meeting - Pisa, December 17th
Wouter Verkerke, NIKHEF

2. Outline ECAL longitudinal profile
– Longitudinal Delta Z measurement on MC events (el 128 GeV)
Focusing on DATA (TB 120 GeV) MC comparison (el 128 GeV)
Electron/MIP Signature comparison in the :
ToF counters
Upper part
Lower part
RICH
Hit multiplicity in the Rich
“ but the hit used in the ring
Tracker
Inner and auter layers
Correlations
ToF/Rich ToF/Ecal Rich/Tracker(#9) Rich/Ecal Tracker(#9)/Ecal

3. Principle
Fit the Longitudinal profile and determine the maximum of the shower Gamma function
by adding material in front of th Ecal, the shower will start earlier
As showed in previous presentations (S.Rosier AMS meeting Nov 11th, ECAL meeting 17th )
Reference data TestBeam 2007
ECAL alone (Plus Tracker layers 2 ? )
EcaL with 2mm of Lead in front, equivalent to 0.4 X0 (what was supposed to be in front of the Ecal with the SC Magnet)
Ref papers
C.Goy Calor 2008 The AMS-02 3D-imaging calorimeter: A tool for cosmic rays in space. J.Phys.Conf.Ser.160:012041,2009
C.Goy and S.Rosier et al. AMSNote

4. Selection – First step Data sample Electrons
ISS B538 (all data processed but a fraction will be shown(ie last 2 months)
Test Beam B538, ele180
Electrons
Vertical particles (spanx<1 and spany<1)
Rely on TRD : TRD Likelihood [ ] (old version)
based on Vitaly’s selection for EM (elec)-> Will use the Melanie’s tools
1 EM shower, 1 track, 1 TRD track
Tracker “Good“ track
Negative charge , Pmom< -1 GeV/c
Spatial Matching between the track and the shower and the track and the TRD track
Ecal selection based on lateral variables ( S3/S5 x,y, Lateral dispersion, etc)

5. ISS data comparison with TB data 2007
ISS B GeV (4 last months)
TB GeV
An overall shift of the shower is observed (max and in the first layers)

6. ISS 10 GeV – Fit
ISS 10 GeV max at 6.13 ± 0.03 (stat) ± syst (0.1) Layer Unit
TB @10 GeV ± 0.03 ± (0.1) Layer unit

7. TB data @ 180 GeV August – Fit
TB 180 GeV max at ± 0.05 (stat) ± syst (tbd) Layer Unit
TB @180 GeV ± ± (0.1) Layer unit

8. MC electron 128 ΔX0 from Delta Z (MC el 128)
Longitudinal Profile fit performed event by event, comparing the maximum of the longitudinal profile to the reference number as measured in 2007 (TB)*
Compared to previous presentations (11th Nov, 17th Nov, 24th , reweighted from the incidence angle à
MC ΔZ= 0.54 ±0.05(stat) ± 0.08(syst) (X0unit)
Data TB ΔZ= 0.75 ±0.05(stat) ± 0.08(syst) (X0unit)
* Ref
- S.Rosier et al, 11th , 17th , 24Th November AMS meetings
- Cecilia and Bruna B. and her team has performed the measurement (fitting event by event and found ~0.6 X0, using x0=1.07 Layer unit, different reference number,different pre selection …)
ΔZ(MPV) = 0.54 (X0unit)
<ΔZ0> = 0.45 (X0unit)
ΔZ (X0unit)

9. Outline ECAL longitudinal profile
– Longitudinal Delta Z measurement on MC events (el 128 GeV)
Focusing on DATA (TB 120 GeV) MC comparison (el 128 GeV)
Electron/MIP Signature comparison in the :
ToF counters
Upper part
Lower part
RICH
Hit multiplicity in the Rich
“ but the hit used in the ring
Tracker
Inner and auter layers
Correlations
ToF/Rich ToF/Ecal Rich/Tracker(#9) Rich/Ecal Tracker(#9)/Ecal

10. Selection Data sample MIP Electrons
Test Beam B538 el120, MC el128 , MCpr400 GeV
MIP
Using ECAL (loose selection S3/S5 >0.98)
Abs(Z)==1
Energy< 1 geV
TrdLoglikh>0.7
Electrons
Rely on TRD : TRD Likelihood [ ]
based on Vitaly’s selection for EM (elec)
1 EM shower, 1 track, 1 TRD track
Tracker “Good“ track
Negative charge , Pmom< -1 GeV/c
Spatial Matching between the track and the shower and the track and the TRD track
Ecal selection based on lateral variables ( S3/S5 x,y, Lateral dispersion, etc)

11. Hit multiplicity in the Upper layers of the ToF
Similar behaviour on X and Y views

12. UPPER TOF-layer 2 MC electron 128 GeV TB electron 120 GeV
Comparing MIP and Electron signal in the Upper ToF
MC electron 128 GeV
TB electron 120 GeV
Interaction
probability
Dx0 MC
(expec)
MC (meas)
(MC)
Data (meas)
ToF1
0.235
18.2%
0.24
21.6 % (>1)
0.28
ToF2
0.25
19.2%
0.253
23.6 % (>1)
0.305
Measuring the interaction rate in front of the second upper TOF Layer (fraction of events with N_cluster > 1)
-> relatively well modeled (slightly more material in Data wrt MC)

13. Time measurement (red data 120 GeV) (blue MC 128 GeV)
Wouter Verkerke, NIKHEF

14. Time measurement (red data 120 GeV) (blue MC 0512 <10 GeV)

15. Time measurement (red data 120 GeV) (blue MC 128 GeV)

16. Time measurement (red data 1317-10 GeV) (blue (MC 0512 <10 GeV)

17. Hit multiplicity in the Lower part of the ToF
Similar behavior on X and Y views – more interactions wrt Upper ToF

18. UPPER TOF-layer 4 Comparing MIP and Electron signal in the Lower ToF
MC electron 128 GeV
TB electron 120 GeV
Interaction
probability
Dx0 MC
(expec)
MC (meas)
(MC)
Data (meas)
ToF3
0.358
28.2%
45.5 % (>2)
0.54
ToF4
0.415
32.9 %
0.41
47.4 % (>2)
0.56
Measuring the interaction rate in front of the second lower TOF Layer
(interacting part if Nclusters>2 )
Trend : more material in data than in MC

19. Time measurement – MC128 GeV – data(red) 120 TB

20. Time measurement – data(red) <10 1317 (20 Days on ISS)

21. Time measurement – MC128 GeV – data(red) 120 TB

22. Time measurement – data(red) <10 1317 (20 Days on ISS)

23. Energy in the Lower part of the ToF
Similar behavior on X and Y views and more interactions wrt the upper tof
ToF group is measuring this more accurately

24. Multiplicity in the Rich
Comparing MIP and Electron signal in the Rich
MC electron 128 GeV
TB electron 120 GeV
Interaction
probability
Dx0 MC
(expec)
MC (meas)
(MC)
Data (meas)
Rich
0.468
37.8 %
0.463
53.6 % (>=10)
0.62
Measuring the interaction rate in front of the Rich.
(Interacting part if Nhit>=10)
Trend more material in data than in MC

25. Rich – Removing hits used in the ring
Comparing MIP and Electron signal in Rich
MC electron 128 GeV
TB electron 120 GeV
Comparing MIP on data and MC
Measuring the interaction rate in front of the Rich
Trend-> more material in data than in MC

26. Tracker – TB120 GeV – Y view
Deposit Energy in each layer using the hits and cluster belonging only to the track
Efficiency : 100% layer 2, % for the others(1,3,4,5,9) but the layer # 8 < 50 %
Ask for at least one cluster in the layer

27. Tracker – TB120 GeV
Layer #8 : Different behaviour for layer # 8 wrt the rest (lower rate of events with a cluster)
Layer #9 : Tail - More signal compared to the other layers Similar and slightly more pronounced on X side

28. Tracker – TB120 GeV – Y view
Layer #8 : Different behaviour for layer # 7 wrt the rest (lower rate of events with a cluster)
Layer #9 : Tail - More signal compared to the other layers

29. Tracker – MC128 GeV
Layer #8 : Different behaviour for layer # 7 wrt the rest (lower rate of events with a cluster)
Layer #9 : Similar to other layers (#1,..)
All the maximum roughly at the same location

30. TB120GeV – MC128 GeV- Layer 2
Measuring the interaction rate in front of the first inner Tracker layer (Upper Tof+ TRD +laye #1)
-> slightly more material in data than in MC

31. TB120GeV – MC128 GeV- Layer 6
Measuring the interaction rate in front of the sixth inner Tracker layer
-> discrepancy Data/MC increases wrt to the first inner tracker layer

32. TB120GeV – MC128 GeV- Layer 9
Measuring the interaction rate in front of the Tracker layer #9
-> discrepancy Data/MC increased wrt to the other layers

33. TB120GeV – MC128 GeV- Layer 9

34. Correlation RICH-ECAL - Longitudinal profile
- The shower maximum is more shifted for higher hit multiplicity in the Rich
- Impact of the selection on this DelatZ shift

35. Correlation RICH-ECAL Lateral dispersion
Layer 1
Layer 2
The lateral dispersion is increasing with the hit multiplicity in the Rich
If different on the MC, could explain Data/MC differences cf A.Fiasson (September 11) or S.Difalco (November 11th)

36. Correlation TOF-ECAL Longitudinal profile
ToF layer #4
The longitudinal profile shift is increasing with the hit multiplicity in the ToF

37. Deposit Energy in the Tracker % ToF
Tracker Layer#9 Y View
Compared to ToF Layer#4
Tracker Layer#9 Y View
Compared to ToF Layer#3
Tracker Layer#9 X View
Compared to ToF Layer#4
!! Tracker – TOF spatial correlation !!

38. Summary Applying the longitudinal profile method
on Monte Carlo events (B512)
ΔZ= 0.54 ±0.05(stat) ± 0.08(syst) x0 units
in agreement with what was expected (V.C, M.I)
on going : measurement on the average profile and measurements at different energies
A relative good agreement between data and MC is observed on the upper part of AMS, less true on the lower part
Correlations between ToF/Rich/Ecal and Tracker
Impact on the shower development the ECAL on both lateral and longitudinal variables and effect on this pre-showering on the E measurement.
Impact on e+/- identification
an excess >.15 x0 is seen in TOF3, TOF4,RICH and ECAL )

39. Interaction probability- > Dx0MC
(expec)
MC (meas)
(MC)
Data (meas)
ToF1
0.235
18.2%*
0.24
21.6 % *(>1)
0.28
ToF2
0.25
19.2%*
0.253
23.6 % * (>1)
0.305
ToF3
0.358
28.2%*
45.5 % * (>2)
0.54
ToF4
0.415
32.9 %*
0.41
47.4 % * (>2)
0.56
Rich
0.468
37.8 %*
0.463
53.6 % * (>=10)
0.62
ECAL
0.75
MLI
(0.016)
an excess >.15 x0 is seen in TOF3, TOF4,RICH and ECAL, *errors on those numbers are ongoing, contribution of backsplash also to be estimated)