“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

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

THE MEXICAN GROUP R. López

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

Participants R. López

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

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

Industry R.López Rotomolded Polyethylene Tanks

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

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

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

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

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

LabView based DAS

Three types of triggers Vertical muons

~74 pe

Arbitrary muons Threshold of 30mV

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

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

No PMT Glass Cherenkov signal

With PMT Glass Cherenkov signal

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

No PMT Glass Cherenkov signal

With PMT Glass Cherenkov signal

Stopping muons and eletrons

Stopping muons and eletrons Single Muons

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

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

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

Parameters for Data and Composed Events Data 8   e 4  33 e 0  66 e Charge (VEM) Amplitude (V) T10-50 (ns) T10-90 (ns)

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)

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

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

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%

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.