1. “Separation of cosmic-ray components in a single water Cherenkov detector" Yasser Jerónimo, Luis Villaseñor IFM-UMSNH X Mexican School of Particles and Fields Playa del Carmen November 5, 2002 H. Salazar FCFM-BUAP

2. Contents  Celebration in Honor of Augusto and Arnulfo  Arnulfo and Auger  Motivation to study  /EM separation  Experimental setup  Data  Composition of showers with known   Use of neural networks  Conclusions

3. THE MEXICAN GROUP R. López

4. Objectives Take part in a major UHE cosmic ray project Graduate students Popularize physics of cosmic rays Motivate and involve Mexican industry in the project R.López

5. Participants R. López

6. Students Graduated R. López ~6 refereed papers, ~60 in proceedings and ~200 talks for general public

7. Activities in Mexico Water Cherenkov detectors in Puebla and Morelia (ICFA Instrumentation Center), Calibration, Schmidt Optics, Simulation, Theory, Data Analysis.

8. Industry R.López Rotomolded Polyethylene Tanks

19. Use low energy showers to study  -EM separation Look here To understand over there

20. 1.54 m diameter, 1.2 m water, 1 8” PMT, tyvek 1/5 in volume of an Auger WCD

21. 2GS/s vs 40MS/s ns for Auger

22. Stopping muon at 0.1 VEM Decay electron at 0.18 VEM Crossing muon at 1 VEM Alcaraz et al., NIM 2000

23. Measure Charge, Amplitude,T10-50,T10-90 with good precision

24. LabView based DAS

25. Three types of triggers Vertical muons

26. ~74 pe

27. Arbitrary muons Threshold of 30mV

28. R muon=876 Hz R sm+e=80 Hz R shower (Q>7VEM)=1 Hz Low Charge Peak=0.12 VEM Stopping muons and eletrons Not an Artifact due to V threshold

29. Stopping muon at 0.1 VEM Decay electron at 0.18 VEM Crossing muon at 1 VEM Qpeak=0.12 VEM Stopping Muon or electron of ~30MeV

30. No PMT Glass Cherenkov signal

31. With PMT Glass Cherenkov signal

32. Stopping muons and eletrons Charge Distributions for Crossing and stopping muons around 1 and.12VEM

33. No PMT Glass Cherenkov signal

34. With PMT Glass Cherenkov signal

35. Stopping muons and eletrons

37. Stopping muons and eletrons Single Muons

38. Stopping muons and elctrons Single Muons Separation of individual Muons and Stopping muons or electrons possible

39. Stopping muon or electron Q~0.12 VEM T12~3ns Isolated Muon Q~1 VEM T12~12 ns Shower Q>7 VEM T12>15ns

40. Data trace Q=7.8 VEM 8 muons 15 ns 4 muons, 15ns 33 “electrons” 25 ns 66 “electrons” 25 ns

41. Parameters for Data and Composed Events Data 8   e 4  33 e 0  66 e Charge (VEM) 7.9+- 0.5 8.0+- 0.55 7.9+- 0.51 8.34+- 0.4 Amplitude (V) 1.16+- 0.08 1.20+- 0.20 1.25+- 0.20 1.34+- 0.19 T10-50 (ns) 16.7+- 0.9 17.5+- 3.0 18.25+- 3.6 18.45+- 2.9 T10-90 (ns) 50.8+- 2.0 50.0+- 4.3 52.4+- 6.6 54.2+- 6.9

42. Training and Clasification Results for a Kohonen Neural Network 4 features as input (Charge, Amplitude, T 10-50, T 1090 ) 8 Neurons in first layer 4 in second layer 2 or 3 classes as output (8 , 4  + 33e, 66e)

43. Training and Clasification Results for Two Classes 8  4  33 e Data 8  65%39%68% 4  33 e 35%61%32%

44. Training and Clasification Results for Two Classes 8  0  66 e Data 8  65%33%78% 0  66 e 35%67%22%

45. Training and Clasification Results for Three Classes 8   e   e 0  66 e Data 8  56%29%33%58%   e 21%35%27%15% 0  66 e 23%36%40%27%

46. Conclusions  Clear separation of crossing muons, PMT interactions, stopping muons and showers in a single WCD  Rise time 10-50% is linear with Q/V  Neural Networks classify composed events of muons and “electrons” better than randomly  Shower data is dominated by muons  To do: use real electron pulses from  decay and other features like power spectrum distribution. Use wider Auger showers (  s  with 25 ns sampling time.