RECONSTRUCTION OF EXTENSIVE AIR SHOWERS FROM SPACE
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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… ). P ierre Colin Dmitry Naumov Patrick Nedelec. Physics hopes. Purpose : Reconstruct initial UHECR parameters.

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P ierre Colin Dmitry Naumov Patrick Nedelec

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P ierre colin dmitry naumov patrick nedelec

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


P ierre colin dmitry naumov patrick nedelec

Physics hopes

Purpose: Reconstruct initial UHECR parameters

Energy (spectrum)

Direction (UHECR sources map)

Particle type

(proton, iron, neutrino, gamma, etc.)

?


P ierre colin dmitry naumov patrick nedelec

Shower parameters

UHECR :

Angles (Zenithal θ and Azimuthal φ)

Altitude of shower maximum: Hmax

Depth of shower maximum: Xmax

Total energy released E

E

Xmax

Hmax


Detection from space

Detection from space

EUSO simulation

Extensive air shower

Air fluorescence (isotropic)

Cerenkov light

(directional)

Ground scattering

Space telescope

SIGNAL = f(t)

UHECR

Cerenkov

echo

Fluorescence

Cloud


Data fit

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 fitFluorescence Cerenkov Background


P ierre colin dmitry naumov patrick nedelec

Key parameter

Golden event

Need Cerenkov echo

Fluorescence event

Only signal shape

TWO METHODS

Monte Carlo Data

Signal analysis (Trigger conditions): 3 samples of events

Fluorescence events

Golden events (Fluo+Cer)

Cerenkov events

Reconstruction


P ierre colin dmitry naumov patrick nedelec

z

EUSO

R

α

Fluorescence

ΔH = Hmax - Hcer

ΔH

y

Cerenkov echo

x

ΔH

Hmax = ΔH + Hcer

  • Disadvantage:

  • We need to know Hcer to reconstruct Hmax

    • : Relief, Cloud altitude (Lidar?)

Hmax reconstruction : Cerenkov method

(Classical method)

For golden events :

We use Cerenkov echo

: Time between Cerenkov and fluorescence maximum


P ierre colin dmitry naumov patrick nedelec

Hmax reconstruction : Cerenkov method

Test of the method: no cloud events (Hcer = 0 )

Reconstructed Hmax vs Simulated Hmax

Relative Erreur

Error<10% for <60°

  • Method not efficient for large  angle (horizontal EAS)


P ierre colin dmitry naumov patrick nedelec

In one GTU i: Li = LGTU

Ni η·Y·Ne·LGTU

= # detected ph/GTU

Transmission η has also a smooth variation with altitude

Niis quite independent of the altitude: Ni Ne

Nmax (η·Y)max·Nemax·LGTU

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


P ierre colin dmitry naumov patrick nedelec

Hmax reconstruction : Shape method

For horizontal showers:

Total shower lenght: L =  LGTU = xtot / (h)

L20=100 km

5 km

20 km

Xtot = L·(h)

L5 = 15 km

Ntot =  Ni  η·Y·< Ne>·L  η·Y·<Ne>· xtot / (h)

Ntot varies dramatically with altitude:


P ierre colin dmitry naumov patrick nedelec

Hmax reconstruction : Shape method

Generalization for all  angles :

Thanks to η & Y smooth variation with altitude

Approximation:

<η·Y·Ne>= (η·Y)max·< Ne>

< (h) > = (Hmax)

Varies like ln(E)

Nmax/Ntot  (Hmax)

(Hmax)

Hmax


P ierre colin dmitry naumov patrick nedelec

Hmax reconstruction : Shape method

Test of the method:

Reconstructed vs Simulated Hmax

Relative Erreur

Error<10% for >60°

Good Method to reconstruct large  angle EAS !


P ierre colin dmitry naumov patrick nedelec

Direction reconstruction :

Available information: for every GTU

Photon incident angles: ix, iy

There is relationship between (ix,iy) and (θ,φ) angle of EAS.

Reconstruct Θ

Reconstruct 

Direction:

σ ~ 2°

Simulated 

Simulated

Assuming infinite pixel resolution


P ierre colin dmitry naumov patrick nedelec

Xmax reconstruction

(reconstructed Xmax – simulated Xmax)(Θ)in g/cm2

Golden events

fluorescence events

Hmax by shape method

Hmax by Cerenkov echo

σ<5% for <50°

σ ~ 10 %


P ierre colin dmitry naumov patrick nedelec

Energyreconstruction

for 1020 eV proton

σ = 22%

E reconstructed by shape method (fluorescence)


Shape method good for uhe neutrinos

Shape method good for UHE neutrinos!

neutrinos

protons

Neutrinos create mainly horizontal EAS without Cerenkov echo.


P ierre colin dmitry naumov patrick nedelec

Conclusion

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

  • using Cerenkov echo

  • Efficient for “vertical” showers (<60°)

  • Need complementary information (echo altitude)

  • using only signal shape

  • Efficient for “horizontal” showers (>60°)

  • UHE Neutrino astronomy from space is possible

We can reconstruct any  EAS: 0° to 90° or more !

This first trial is very promising.


Bonus slide

BONUS SLIDE


Simulated data

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

αy

αx

Extensive air shower

Hmax

y

x


If we add pixel resolution

If we add pixel resolution:

EUSO simulation

EUSO event on focal plan (M36)

Error : more from detector than from method


P ierre colin dmitry naumov patrick nedelec

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

Xmaxfor fluorescence events

Xmaxfor Golden events


P ierre colin dmitry naumov patrick nedelec

Energyreconstruction

Y : Fluorescence yield (ph/m)

Kakimoto Model

η : Atmosphere transmission

Lowtran Model

ε : Detector efficiency

ΔΩ : Detector solid angle


P ierre colin dmitry naumov patrick nedelec

Energyreconstruction


Detection from space1

Detection from space

EUSO simulation

SIGNAL = f(t)

Extensive air shower

Air fluorescence (isotropic)

Cerenkov light

(directional)

Air scattering

Ground scattering

Space telescope

UHECR

Cloud


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