Extensive air shower muons: the key of the UHECR puzzle

Extensive air shower muons: the key of the UHECR puzzle

Extensive Air Shower Muons
The key of the UHECR puzzle
L. Cazon
L Cazon
NWPAC 29-31 Jan, 2014 Braga
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Ultra High Energy Cosmic Rays
Detection of
Primaries
Satellites, Balloons
Detection of
Secondaries (Shower)
Ground Arrays
GZK-cutoff
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UHE Particle Physics & UHE Astrophysics
Window of oportunity
UHECR: exciting and puzzeling.
• A few nearby sources shooting iron, with high B deflections?
• Many sources shooting protons?
• Combinations of both? Intermediate compositions He, C, N, O?
If we could separate UHECRs by composition
•
Beam for UHE particle physics
•
Dawn of UHE Charged Particle Astronomy
But changes in hadronic physics and changes in CR composition often mock each other
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Electrons
Photons
Muons
Neutrons
protons
Electrons
Photons
Muons
Neutrons
protons
Primary:
Hadron
Hadronic shower
(mainly pions)
Muonic component
Electromagnetic shower
(electrons and photons)
Muons are the smoking gun of the
hadronic cascade which is the real
backbone of the whole shower.
L Cazon
Primary:
Photon
Hadronic skeletons

L Cazon

Hadronic reaction
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L Cazon
A
A
A
A
A
A
Generation
ordered
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J. Matthews Astropart.Phys.
22 (2005) 387-397
Hadronic cascade
E0
1
N ch

0

N ch2
E0
2
N tot
E0
3
N tot
N ch3
c 
20 GeV
L Cazon
E0
N tot
E 
ln  0 
c 
 E0 

nc 
 0.85 log10   
3

 c 
ln  N ch 
2

N tot
1
 N ch  N ch
2
The hadronic
cascade loses
energy that goes into
the EM cascade
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J. Matthews Astropart.Phys.
22 (2005) 387-397
EM cascade
1
E0
2
E0 / 2
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E0 / 22
23
E0 / 23
24
E0 / 24
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ce  85MeV
 E0 
ln  e 
c 

nc 
ln 2
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Composition scaling
X max
X

 E0 
 nc r ln( 2)  r ln  e 
 c 
max
 E0 
 i nc  i 0.85 log10   
 c 

 E0 
N     


 c  E0 
N     
ln(1 N ch )
 c   1  0.14

 1  N ch 
ln 

1

3
/
2



A= UHECR mass number
 E0

X max ( A)  r  ln
 ln  ce   X max  ln A
 A

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  E / A  
ln N  ( A)  ln  A 0     ln N   (1   ) ln A
   c  
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Energy balance
dE
 Ne( X )dX   dX dX Ecal
 h( X )dX  N 
EM channel ends up carrying all
the shower energy except a small
remaining fraction fraction called
“Invisible energy”
E0  Ecal  bN 
1 
N ch
p  (1  k ) E
 
1
N ch   0
2
 c  20 GeV

X max
h(X)
L Cazon
X
EM
max
Ne(X)
  0.2
 1
 1
2
kE
3
1

kE
3

k=inelasticity
EM
n
 1 
 E  1  3   E0

  1 n 
EM
E

1  1    

  3  
  0.5
Hadronic
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Full MC simulations &
Auger data
L Cazon
Full MC simulations &
Auger data
LHC-EPOS makes a better treatement of diffraction rapidity gaps.
QGSJetII.04 could be missing additional and relevant effects that compensates Xµmax
Deficit of Nµ in all models
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σ(Xµmax)
Events
Xµmax
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Events
σ(Nµ)
E [eV]
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E [eV]
Nµ
Event by event
Mass Separation
Xmax - Nµ plane
L Cazon
NWPAC 29-31 Jan, 2014 Braga
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Mass / Hadronic models
Disentanglement
Mock data point
p
< Nµ > - σ (Nµ )
He
N
Fe
<Xmax> - < Nµ >
L Cazon
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R. Conceição
Conclusions
• EM component is the most exploited sector of the air
shower to study UHECR
• Muons carry information from the hadronic skeleton of
the shower. They are experimentally underexploited.
• The momenta of Nµ , Xmax and Xµmax distributions are
very sensitive tools to high energy interaction models
and average masses
• The combined use of Nµ with Xmax event by event
could separate primaries regardless of high energy
interaction models.
• Clean(er) beam for UHE particle physics and UHE
astrophysics
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L Cazon
NWPAC 29-31 Jan, 2014 Braga
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X max
X


 E0 
N     
 c 
ln(1  N ch )

 1  0.14
 1  N ch 
ln 

 1  3 / 2 
 E0 
 nc r ln( 2)  r ln  e 
 c 
max
 E0 
 i nc  i 0.85 log10   
 c 
 E0
e
X max ( A)  r  ln
 ln  c   X max  ln A
 A


 E0 / A 
N  ( A)  A    A1  N 
 c 
ln N  ( A)  ln N   (1   ) ln A
L Cazon
NWPAC 29-31 Jan, 2014 Braga
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mair
X 1 ( E )  i ( E ) 
 p air ( E )
 Aair ( E )  A p air ( E / A)
L Cazon
NWPAC 29-31 Jan, 2014 Braga
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Multivariant analysis
Larger discrimination
power
K.H. Kampert &
M.Unger 2011
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NWPAC 29-31 Jan, 2014 Braga
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