On the possibility to discriminate the mass of the primary cosmic ray using the
muon arrival times from extensive air showers:
Application for Pierre Auger Observatory.
N. Arsene1,2, H. Rebel 3, O. Sima 2
1ISS
Bucharest, Romania, 2University of Bucharest, Romania, 3KIT, Karlsruhe, Germany
1
Content :
1.
Cosmic rays energy spectrum
2.
Extensive air showers (EAS)
3.
EAS experimental techniques at the Pierre Auger Observatory (PAO)
4.
Methods to determine mass of primary cosmic ray
5.
On the possibility to discriminate the mass of the primary cosmic ray
using the muon arrival times
6.
Results and outlook
2
1. Cosmic rays energy spectrum
T heenergyspectrumof primarycosmicrays
extendsfrom1 GeV to above1020 eV
J(E)  E  γ
J(E)  1 particle/ m2s to 1 particle/ km2century
" knee" 1015  1016 eV
" ankle" 6 x 1019 eV
Greisen–Zatsepin–
Kuzmin cutoff
(GZK cutoff)
5 x 1019 eV
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2. Extensive air showers (EAS)
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2. Extensive air showers (EAS)
(Xmax  X0 ) ~ E0 and primarymass
(X Xmax ) ~ lnE0
nucleus primary(A nucleons)
X max ~ E 0 /A  X max ~ lnA
( Xmaxp - XmaxFe ) ≈ 100 g cm-2
Gaisser–Hillas :
λ  70 g/cm2
Nishimura–Kamata–Greisen (NKG) approximation :
Nch = the total number of charged particles
s = “age” parameter
r0 = Moliere radius ~ 79 m
C = constant
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2. Extensive air showers (EAS)
Heck D. et al.[3] Longitudinal EAS
development. MC simulations with CORSIKA
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3. EAS experimental techniques at the Pierre
Auger Observatory (PAO)
Southern Hemisphere, Argentina
Primaryenergy  1018 eV exceeding1021 eV
Surface 3000 km2
1600 surface detectors water Cherenkov
(SD)
4 stations fluorescence detectors
A. Creusot [4]
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3. EAS experimental techniques at the Pierre
Auger Observatory (PAO)
Water Cherenkov tanks
AUGER COLABORATION [5]
altitude 1500 m
diameter 3.6 m
height
1.55 m
detects : muons, electrons,
positrons, photons
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3. EAS experimental techniques at the Pierre
Auger Observatory (PAO)
Surface detectors reconstruction
AUGER COLABORATION [5] , Eveniment recorded by Pierre Auger Observatory , E = 5 x 1018 eV
Primary energy :
E(EeV)  0.12 [ 1  11.8(sec(  ) - 1) 2 S(1000)] 1.05
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3. EAS experimental techniques at the Pierre
Auger Observatory (PAO)
Fluorescence detectors (FD)
Jos Bellido, for the ́ Pierre Auger Collaboration [6]
3.5 m x 3.5 m spherical mirror -> 440 PMT camera
Field of view 300 azimuth x 28.60 elevation
1 pixel -> 1.50
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3. EAS experimental techniques at the Pierre
Auger Observatory (PAO)
Fluorescence detectors (FD) reconstraction
Shower Detector Plane reconstruction :
χ 2   w i (nSDP  ri ) 2  minimum
i
wi  signal in pixel" i"
ri  direct ionin t hesky
n SDP  vector SDP
nSDP errors ̴ tenths of a degree
Shower Axis reconstruction :
AUGER COLABORATION [5]
t i,exp  t 0  R p /c tan[(0 - i )/2]
Shower axis errors ̴ 1 degree
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3. EAS experimental techniques at the Pierre
Auger Observatory (PAO)
Fluorescence detectors (FD) reconstraction
AUGER COLABORATION [5] Eveniment recorded by PAO, zenith angle = 56º , distance core - FD detector = 13 km
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4. Methods to determine mass of
primary cosmic ray
Dependence of Xmax :
M. Risse [8] Longitudinal showers profile . MC simulations, E=10^19 eV, vertical
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4. Methods to determine mass of
primary cosmic ray
Correlation between Xmax and Nµ (Patrick Younk and Markus Risse, 2009) :
Patrick Younka, Markus Rissea [9] Xmax - Nµ distribution , E = 1019 eV, zenith = 45 ͦ. Average per 1000 simulations
using Conex code with QGSJET-01 model
a)
b)
Ideal detectors
Real detectors : σ Nµ = 20 %
σ Xmax = 20 g cm-2
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4. Methods to determine mass of
primary cosmic ray
Time asymmetry in the shower development
Hernan Wahlberg, for the Pierre Auger Collaboration [10]
Position of maximum asymmetry vs.
primary energy for different models and primaries.
Hernan Wahlberg, for the Pierre Auger Collaboration [10]
Asymmetry development for the different samples
t ½ = mean risetime
r = radius
ζ = azimuth angle
Θ = zenith angle
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5. On the possibility to discriminate the mass of the
primary cosmic ray using the muon arrival times
Proposed by H. Rebel et al. for KASCADE colaboration, 2003 [12]
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6. Results and outlook
Azimuthal distributions of muons in observable plane.p, E=8x10^17eV, zenith=30,S->N, CORSIKA - QGSJET01 model
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6. Results and outlook
Momentum distribution of muons at ground , CORSIKA simulations – QGSJET01 model
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6. Results and outlook
Distribution of arrival times of muons at ground , CORSIKA simulations – QGSJET01 model
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6. Results and outlook
Distribution of the reconstructed atmospheric depth of muon production , CORSIKA simulations –
QGSJET model
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6. Results and outlook
Distribution of the reconstructed atmospheric depth of muon production using infill array detectors, average over
10 simulations (left) and 100 simulations (right)
30 +/- 3 muons in infill detectors Fe, E=8x10^17 eV
20 +/- 2 muons in infill detectors p, E=8x10^17 eV
Xmax
mu
p
≈ 400 g cm-2
Xmax
mu
Fe
≈ 250 g cm-2
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6. Outlook
Average number of muons per square meter as a function of radial distance to the core of
the shower. Averaged over 100 showers with one sigma as error bars. Zero inclination. [11]
- Analisys of a large set of CORSIKA simulations with primary energy above 10^18 eV
- Find maximum distribution of the reconstructed atmospheric depth of muons production
- Possibility to implement this method as a complementary method for determine the primary cosmic ray mass
in Pierre Auger Experiment
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Bibliography :
[1] Engel R. et. Al. 2011, Annu Rev. Nucl. Part. Sci. 61:467-89
[2] Diego Garca Gamez, 2010, Dpto. de Fsica Teorica y del Cosmos & CAFPE
Universidad de Granada
[3] Heck D et al 1998 FZKA Report Forschungszentrum Karlsruhe 6019
[4] A. Creusot, 2010, Latest results of the Pierre Auger Observatory, Nuclear Instruments
and Methods in Physics Research A 662 (2012) S106–S112
[5] AUGER COLABORATION, Properties and performance of the prototype
instrument for the Pierre Auger Observatory, Nuclear Instruments and Methods in
Physics Research A 523 (2004) 50–95
[6] Jos Bellido, for the ́ Pierre Auger Collaboration, Mass Composition Studies of the Highest Energy
Cosmic Rays, arXiv:0901.3389v1 [astro-ph.HE].
[7] M. Unger, et al [Pierre Auger Collaboration], Proc. 30th ICRC, , Merida, (2007),
arXiv:0706.1495v1 [astro-ph].
[8] M. Risse, Acta Phys.Polon. B35 ,1787, (2004), arXiv:astro-ph/0402300v1.
[9] Patrick Younka, Markus Rissea, Sensitivity of the correlation between the depth of shower
maximum and the muon shower size to the cosmic ray composition, 10.1016/j.astropartphys.2012.03.001.
[10] Hernan Wahlberg, for the Pierre Auger Collaboration, Mass composition studies using the
surface detector of the Pierre Auger Observatory , Nuclear Physics B (Proc. Suppl.) 196 (2009) 195–198 .
[11] Jochem D. Haverhoek, 2006 , Ultra High Energy Cosmic Ray Extensive Air Shower simulations using CORSIKA
[12] I.M.Brancus ,H.Rebel, A.F.Badea et. al. J.Phys.G29:453-474,2003 Features of Muon Arrival Time
Distributions of High Energy EAS at Large Distances From the Shower Axis
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M. Unger, et al [7] Auger results for the Mean Xmax
measurements as a function of energy
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