WATER CHERENKOV DETECTOR ARRAY at the University of Puebla to study

cosmic rays

H. Salazar , J. Cotzomi, E. Moreno, T.Murrieta, B.Palma,

E.Perez, L. Villaseñor

FCFM-UAP

EAS-BUAP : Design and Preliminary Results of the water Cherenkov array

Main goal:

Contribute to the study of inclined showers and mass composition around the knee as well as educational training.

*11+1 tanks filled with a layer of 12 cm high of liquid scintillator and 1 m2 effective area, mounted in a rectangular grid (40x100m2, 20m spacing).

*3 Water Cherenkov detectors 2 m2 effective area

1 Water Cherenkov Detector (WCD), 10m2 effective area, 1.2m height.

Full array and operational detectors in red .

All signals are collected in a central acquisition station.

EAS-UAP: First Stage, scintillator detectors.

EAS-UAP

Altitude ~2200 m above sea level,

800 g /cm2

Location:

190 N and 900 W.

Energy range covered by the EAS-BUAP array: 1014 to 1016 eV.

The primary energy spectrum extends over many Orders of magnitude from GeV energies to 50 J.

Power law spectrum with almost no structure

Change in the spectral index at about 4 PeV(Knee)

Slight steepening around 400PeV (second Knee)

Flattening at the highest energies around 10EeV(Ankle)

GZK Cutoff

The origin of the Knee is still under discussion

Cosmic ray particles are most likelyaccelerated in strong shock fronts of

supernova remnants (Fermi acceleration)

Low Z(charge) particles are more likely to escape from the galaxy as compared

to particles with high Z (gyromagnetic radii)

The first Knee is due to the subsequentCut-offs for all elements, starting with

the proton component

Second Knee could mark the end of the stable elements (Z=92)

EAS TOP

ItalyLocation: 2005 m a.s.l. (820 g/cm2)35 detector stations of

scintillators•10m2

Detector: Array, MACRO

Observables: Ne, muonsStatus: stopped

KASKADE

Germany Location: 500 m a.s.l.

(1020 g/cm²).252 scintillator detectors

Area: 200 X 200 m² Detector: Array, tunnel

GRANDEObservables: Ne-Nu,

hadrons, muonsStatus: running in set-up

The trigger requires the coincidence of >4 signals in a rectangular sub-array with an area of 2929 m2. The measured trigger rate is 150 hour-1.

Light-tight cylindrical container with inner reflective walls filled with liquid scintillator up to a height of 12 cm and one 5” PMT (EMI 9030A) facing down 70 cm above the surface of the liquid..

Day/Night temperature effect on rates

Calibration histograms EAS-UAP Scintillation detectors November 2004

Calibration histograms of the Water Cherenkov detectors

Angular distribution inferred directly from the relative arrival times of shower frontin good agreement with the literature: cosp sen

Angular distribution from Cherenkov detector arrival times

A = 4R² cos() + 2hR sen()

Example of lateral distribution of electromagnetic particles fromScintillation detectors

Two examples of LDF for both: EM and VEM

Muon/EM separation in Water Cherenkov detectors

For details see Villasenor L. talk at Rich 2004

Discussion on compositionWe have checked the stability and performed the calibration of the detectors.

We have measured and analyzed the arrival direction of showers. We determine the number of charged particles in each detector using the single-particle charge spectrum to obtain the LDF of (vertical) showers and the water cherenkov detectors to obtain the LDF in VEM’s. The shower core is located by the center of gravity and by fitting the measured charged particle distribution to the NKG function.

Muon/Electromagnetic content from:

S(VEM)= N*VEM + Nem*VEM/W1

S(Nt)= N + W2Nem,

with W1 ~24 and W2 ~2.4 But simulation of

the detection process is needed for fine tuning of these weigths!

CABAÑA

ALT: 4560N 18° 59’ 03.9’’W 97° 18’ 44.7’’

ALT: 4558N 18° 59’ 04.6’’W 97° 18’ 45.4’’ CENTRO

ALT: 4557N 18° 59’ 03.7’’W 97° 18’ 45.5’’

ALT: 4557N 18° 59’ 04’’W 97° 18’ 46.4’’

ALT: 4558N 18° 59’ 02.9’’W 97° 18’ 45.2’’

ARENA

RAMPA

NORTESUR

TOWARDS THE

MOUNTAIN TEST ARRAY

Thanks to INAOE-LMT for the site!

Cherenkov

DETECTORS fluorescence

detector

Construction in progress: Hybrid Mountain Array to determine mass composition

Acknowledgements to students!

Eduardo Moreno, Jorge Cotzomi, Epifanio Lancho, Marcelino Anguiano, Saul Aguilar, Guillermo Ontiveros, Isabel Pedraza, Tirso

Murrieta, Bianey Palma, Gonzalo Perez

Acknowledgements

This work was done with partial support of the CONACY-G32739E

And

University of Torino

University of Puebla

Fermilab

Students:

Eduardo Moreno Barbosa

Jorge Cotzomi Paleta

Epifanio Lancho

Marcelino Anguiano

Saul Aguilar

Guillermo Ontiveros

Isabel Pedraza

Tirso Murrieta

Bianey Palma

Gonzalo Perez

Comparación de un chubasco vertical generado con protón a una energía de 1e17 eV, simulado con GIL, QGSJET, SIBYLL

0.00E+00

1.00E+07

2.00E+07

3.00E+07

4.00E+07

5.00E+07

6.00E+07

0 200 400 600 800 1000

profundidad atmosférica

núme

ro de

partí

culas

GIL

QGSJET

SIBYLL

Scintillator detetctor vs Small Water CD

Infill array: distribution of zenith angle