Hybrid Extensive Air Shower DetectorArray at the University of Puebla to
Study Cosmic RaysO. MARTINEZ, H. SALAZAR, L. VILLASEÑOR*
+ Grupo de Estudiantes
Facultad de Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, Apartado Postal 1364, Puebla, Pue., 72000, México
*On leave of absence from Institute of Physics and Mathematics, University
of Michoacan, Morelia, Mich., 58040, México
EMA 05MoreliaJuly 18-22, 2005
EAS Array
Area: 4000 m^2 10 Liquid Ssintillator Detectors
(Bicron BC-517H) 4 Water Cherenkov Detectors
PMT Electron tubes 9353 K
PMT EMI 9030 A
2200m a.s.l., 800 g/cm2. Located at Campus Universidad Autonoma
de Puebla Hybrid: Liquid Scintillator
Detectors and water Cherenkov Detectors
Energy range 10^14- 10^16 eV
DAQ System
• Trigger: Coincidence of 4 central detectors (40mx40m)
NIM y CAMAC.
Uso digital Osciloscopes as ADCs.
Rate: 80 eventos/h
Monitoring
• Use CAMAC scalers to measure rates of single partícles on each detector.
• Day-night variations <10%
/mean around 3%
Calibration
~74 pe
LabView basedDAS
MPV of EM peak = 0.12 VEMi.e. around 29 MeV, i.e., dominatedBy knock-on + decay electrons
Stopping muonat 0.1 VEM
Decay electronat 0.17 VEM = 41 MeV
Crossing muonat 1 VEM
Alarcón M. et al., NIM A 420 [1-2], 39-47 (1999).
Data Analysis
• Arrival direction
sin sin = d/c(t2-t1)
Angular distribution inferred directly from the relative arrival times of shower frontin good agreement with the literature: cosp sen
Data Analysis
• Lateral Distribution Functions
mR
RRRRSKRS SSNKG
100
)/(1)/)((),(
0
5.40
20
Energy Determination107.1
00 5.197)( EEN
mR
RRRRKRGreissen
400
)/(1)/()(
0
5.20
75.0
EAS-TOP, Astrop. Phys,10(1999)1-9
The shower core is located as the center of gravity.
Ne, obtained for vertical showers. The fitted curve is Ik (Ne/Nek)
-, gives =2.44±0.13
which corresponds to a spectral index of the enerfy distributions of =2.6
Cherenkov
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 i.e., around 10 MeV.
Therefore for 10 Mev electrons we expect:
Mu/EM=24 for Cherenkov
Mu/EM=2.6 for Liq. Scint.
Muon/EM Separation
Mass CompositionHybrid 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
VEMAq
VEMAq
VEMA
q
int
int
71
78
)(724
Solution:
IterationsStart with
Ne=82,300Nmu = 32700E0 = 233 TeV
IterationsEnd with
Ne=68000Nmu = 18200E0 = 196 TeV
Mass CompositionNon-Hybrid Array
24CEM
CmuonC
Cherekov AA
VEMq
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 CompositionNon-Hybrid but Composite
ArrayTwo 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:
