hybrid extensive air shower detector array at the university of puebla to study cosmic rays...
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Hybrid Extensive Air Shower Detector Array at the University of Puebla to Study Cosmic Rays
(EAS-UAP)O. Martíneza, E. Morenoa, G. Péreza, H. Salazara, L. Villaseñora,b.
(a) Facultad de Fisico-Matematicas, Benemerita Universidad Autonoma de Puebla, Puebla, Pue., 72000, Mexico
(b) Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Mich., 58040, Mexico
Abstract
We describe the performance of a hybrid extensive air shower (EAS) detector array built on the Campus of the University of Puebla (19oN, 90oW, 800 g/cm2) to measure the energy, arrival direction and composition of primary cosmic rays with energies around the knee of the cosmic-ray energy spectrum. The array consists of 6 water Cherenkov detectors of 1.86 m2 cross section and 12 liquid scintillator detectors of 1 m2 distributed in a square grid with a detector spacing of 20 m over an area of 4000 m2. We discuss and report on measurements and reconstruction of the LDF for the electromagnetic and muonic components of extensive air showers. We also discuss the ways in which the hybrid character of the array can be used to study inclined EASs, i.e., zenithal angle > 60 degree; and also to measure mass composition of the primary cosmic rays, i.e., by estimating the relative contents of muons with respect to the EM component.
a)
Referencias H. Salazar and L. Villaseñor, Nucl. Instrum. and Meths A, Proc. RICH2004 Conference, 2005. M. Alarcon, et al., Nucl. Instrum. And Meths A 420 (1999) 39-47.J. Nishimura, Handbuch der Physik XLVI/2, (1967) 1.H. Salazar, O. Martínez, E. Moreno, J. Cotzomi, L. Villaseñor, O. Saavedra, Nuclear Physics B (Proc. Suppl.) 122 (2003) 251-254.M. Aglietta et al., Phys. Lett. B, 337 (1994) 376-382.
HE.1.2
EAS-UAP Array(19º N, 90ºW, 800g/cm2)
PMT EMI 9030 A
PMT Electron tubes 9353 KExperimental Setup
2200m a.s.l., 800 g/cm2. Located at Campus Universidad Autonoma
de Puebla Hybrid: Liquid Scintillator
Detectors and water Cherenkov Detectors
Energy range 1014 - 1016 eV
DAQ System
Trigger: Coincidence of 4 central detectors (40mx40m)
NIM y CAMAC. Use of digital Osciloscopes as ADCs
Rate: 80 eventos/h
MonitoringUse CAMAC scalers
to measure rates of
single partícles on
each detector.
Day-night variations
<10%
/mean around 3%
Calibration (Control Experiments)
~74 pe
Decay electronat 0.17 VEM = 41 MeV
Indoors WCD: MPV of EM peak = 0.12 VEM ~ 29 MeV, i.e., dominated by knock-on + decay electrons
Outdoors WCD: MPV of EM peak = 0.12 VEM ~ 29 MeV, i.e., dominated by EM particles ~ 10 MeV
WCD Liquid Scint
Muons deposit 240 MeV in 1.20m high water and only 26 MeV in 13 cm high liquid, while electrons deposit all of their energy.
For 10 Mev electrons we expect:
Mu/EM=24 for Cherenkov
Mu/EM=2.6 for Liq. Scint.
Outdoors Liquid Scintillator Detector: MPV of EM peak = 0.30 VEMi.e., dominated by EM particles ~ 10 MeVAngular Distribution
Angular distribution inferred directly from the relative arrival times of shower front.Zenithal distribution in good agreement with the literature: cosp sen Flat azimuthal distribution
Lateral Distribution Functions
mR
RRRRSKRS SSNKG
100
)/(1)/)((),(
0
5.40
20
mR
RRRRKRGreissen
400
)/(1)/()(
0
5.20
75.0
Energy Determination
107.100 5.197)( EEN EAS-TOP, Astrop. Phys,
10(1999)1-9
Ne, obtained for vertical showers. The fitted
curve is Ik (Ne/Nek) -g, gives g=2.44±0.13
which corresponds to a spectral index of the enerfy distributions of g=2.6
Mass Composition Hybrid Array
3
24
int LEMLmuon
L
LiqSc
CEMCmuon
C
Cherekov
AA
VEM
q
AA
VEMq
LL
LiqSc
CC
Cherekovmuon
CC
Cherekov
LL
LiqScEM
VEMA
q
VEMA
q
VEMA
q
VEMA
q
int
int
71
78
)(724
Iterations Process. Start with Ne=82,300, Nmu = 32700, E0 = 233 TeV
Iteration Process. End with Ne=68000, Nmu = 18200, E0 = 196 TeV
Mass Composition Non-Hybrid Array
24CEM
CmuonC
Cherekov AA
VEM
q
Do a three-parameter fit to :
mR
mR
RRRRKRRRRSKRNRS GreissenSS
NKGGreissenNKG
400
100
)/(1)/()/(1)/)(()(),(
1
0
5.21
75.01
5.40
20
Mass Composition Non-Hybrid but Composite Array
Two Identical types of Cherenkov Detectors one filled with 1.20 m of water and the other with 0.60 m, i.e., VEMC’=0.5VEMC
12
24
'
' EMmuon
CC
Cherekov
EMmuon
CC
Cherekov
VEMAq
VEMAq
)2
(1
)(24
'
'
'
'
C
Cherekov
C
Cherekov
Cmuon
C
Cherekov
C
Cherekov
CEM
VEM
q
VEM
q
A
VEM
q
VEM
q
A
i.e., do independent fits of EM and muon to NKG and Greissen LDF, respectively, where:
Conclusions
We have checked the stability and performed the calibration of the detectors.
We have measured and analyzed the arrival direction of showers.
We determine the energy of the primary by measuring the total number of charged particles obtaining by integration of the fitted LDF.
Study of Muon/Electromagnetic ratio is underway: