arreglo eas-uap para el estudio de rayos cósmicos alrededor de 10 15 ev
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Arreglo EAS-UAP para el Estudio de Rayos Cósmicos alrededor de 10 15 eV. Humberto, Salazar, Oscar Martínez, César Alvarez, L. Villaseñor * + Estudiantes del Grupo de la FCFM-BUAP - PowerPoint PPT PresentationTRANSCRIPT
Arreglo EAS-UAP para el Estudio de Rayos Cósmicos alrededor de 1015 eV
Humberto, Salazar, Oscar Martínez, César Alvarez, L. Villaseñor* +Estudiantes del Grupo de la FCFM-BUAP
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
Coloquio del Grupo de Altas EnergíasCINVESTAV-IPND.F.Sept. 20, 2005
At an energy of approximately 3 PeV the spectral index steepens (“knee”).
To understand the reason for the knee, one must understand the source, acceleration mechanism, and propagation of cosmic rays.
First-order Fermi acceleration has a cutoff energy (protons to 1014 eV and Iron to 3 x 1015 eV)
Observing the mass composition of cosmic rays at the knee therefore provides an important clue to the origin of cosmic rays.
Source
Supernova shock-wave Fermi acceleration is correct + Unknown mechanism i.e., rotating compact magnetic objects (neutron stars or black holes) at higher energies = kink due to overlap between the two mechanisms with progressive change in chemical composition as the knee is approached.
Propagation
Smooth energy distribution up to the highest cosmic-ray energies with unknown loss mechanism beginning at about 1015 eV.
Measuring the chemical composition of the cosmic rays at 1015 eV can test the different explanations.
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 3-4 central detectors (40mx40m) NIM y CAMAC.
Use digital Osciloscopes
as ADCs. Rate: 80
eventos/h
DAQ System
• Calibration Rate: 250 events/m2/s
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).
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
Data Analysis
• Arrival directionsin 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
AAVEMq
AAVEMq
LL
LiqSc
CC
Cherekovmuon
CC
Cherekov
LL
LiqScEM
VEMAq
VEMAq
VEMAq
VEMAq
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 AAVEMq
Do a three parameter fit to :
mRmR
RRRRKRRRRSKRNRS GreissenSS
NKGGreissenNKG
400100
)/(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
VEMq
VEMq
A
VEMq
VEMq
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: