Pierre Colin

1
RECONSTRUCTION OF EXTENSIVE AIR SHOWERS FROM
SPACE

• Stand alone method using only EAS induced light.
• General algorithms for any space project.
• ( EUSO, OWL, TUS, KLYPVE )

Pierre Colin Dmitry Naumov Patrick Nedelec
2
Physics hopes
Purpose Reconstruct initial UHECR parameters
Energy (spectrum)
Direction (UHECR sources map)
Particle type (proton, iron, neutrino, gamma,
etc.)
?
3
Shower parameters
UHECR
Angles (Zenithal ? and Azimuthal f)
Altitude of shower maximum Hmax
Depth of shower maximum Xmax
Total energy released E
E
Xmax
Hmax
?
4
Detection from space
Space telescope
SIGNAL f(t)
UHECR
Fluorescence
Cerenkov echo
Cloud
5
Data fit
Available information for every GTU (Time Unit
2.5 µs)
Number of detected photons Ni
fit 2 Gaussians Fluorescence Cerenkov
constant Background noise

• Monte Carlo data
• - Global fit Fluorescence Cerenkov Background

6
TWO METHODS
Monte Carlo Data
Signal analysis (Trigger conditions) 3 samples
of events
Fluorescence events
Golden events (FluoCer)
Cerenkov events
Reconstruction
7
Hmax reconstruction Cerenkov method
(Classical method)
For golden events
We use Cerenkov echo
Time between Cerenkov and fluorescence
maximum
8
Hmax reconstruction Cerenkov method
Test of the method no cloud events (Hcer 0 )
Reconstructed Hmax vs Simulated Hmax
Relative Erreur
Errorlt10 for ?lt60
Method not efficient for large ? angle
(horizontal EAS)
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Hmax reconstruction Shape method
(Brand new method)
For Fluorescence event
We use only Fluo signal
emitted photon
?L EAS track length
Fluorescence Yield (ph/m)
Ne charged particles in EAS
Y Fluorescence Light Yield
Y smooth variation with altitude
10
Hmax reconstruction Shape method
For horizontal showers
Total shower lenght L ? ?LGTU xtot / ?(h)
L20100 km
5 km
20 km
Xtot L?(h)
L5 15 km
Ntot ? Ni ? ?Ylt NegtL ? ?YltNegt xtot /
?(h)
Ntot varies dramatically with altitude
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Hmax reconstruction Shape method
Generalization for all ? angles
Thanks to ? Y smooth variation with altitude

• Approximation
• lt?YNegt? (?Y)max lt Negt
• lt ?(h) gt? ?(Hmax)

Varies like ln(E)
Nmax/Ntot ? ?(Hmax)
?(Hmax)
Hmax
12
Hmax reconstruction Shape method
Test of the method
Reconstructed vs Simulated Hmax
Relative Erreur
Errorlt10 for ?gt60
Good Method to reconstruct large ? angle EAS !
13
Direction reconstruction
Available information for every GTU
Photon incident angles ?ix, ?iy
There is relationship between (?ix,?iy) and (?,f)
angle of EAS.
Reconstruct ?
Reconstruct T
Direction s 2
Simulated ?
Simulated ?
Assuming infinite pixel resolution
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Xmax reconstruction
(reconstructed Xmax simulated Xmax) (T) in
g/cm2
Golden events
fluorescence events
Hmax by Cerenkov echo
Hmax by shape method
slt5 for ?lt50
s 10
15
Energy reconstruction
for 1020 eV proton s 22
E reconstructed by shape method (fluorescence)
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Shape method good for UHE neutrinos!
neutrinos
protons
Neutrinos create mainly horizontal EAS without
Cerenkov echo.
17
Conclusion

• We have developed two complementary methods to
  reconstruct EAS from space using UV light signal.
• using Cerenkov echo

• Efficient for vertical showers (?lt60)
• Need complementary information (echo altitude)

• using only signal shape

• Efficient for horizontal showers (?gt60)
• UHE Neutrino astronomy from space is possible

We can reconstruct any ? EAS 0 to 90 or more
! This first trial is very promising.
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BONUS SLIDE
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Simulated data
Available information for every GTU (Time Unit
2.5 µs)
Photon incident angles ?ix, ?iy
Number of detected photons Ni
z
Space telescope
?ix, ?iy EUSO simulation
ay
ax
Extensive air shower
?
Hmax
y
?
x
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If we add pixel resolution
EUSO simulation
EUSO event on focal plan (M36)
?
Error more from detector than from method
21
Xmax reconstruction
SLAST simulation of Xmax(g/cm2)
Xmax change with RCUE type Xmax f(E/A) (E/A
is energy by nucleon)
Iron
proton
Test with 10 000 protons and 10 000 iron nuclei
Xmax for fluorescence events
Xmax for Golden events
22
Energy reconstruction
Y Fluorescence yield (ph/m)
Kakimoto Model
? Atmosphere transmission
Lowtran Model
e Detector efficiency
?O Detector solid angle
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Energy reconstruction
24
Detection from space
Space telescope
UHECR
Cloud