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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… ). 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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  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 θ and Azimuthal φ) Altitude of shower maximum: Hmax Depth of shower maximum: Xmax Total energy released E E Xmax Hmax 

  4. 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

  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 fitFluorescence Cerenkov Background

  6. 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

  7. 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

  8. 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)

  9. 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

  10. 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:

  11. 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

  12. 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 !

  13. 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

  14. 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 %

  15. Energyreconstruction for 1020 eV proton σ = 22% E reconstructed by shape method (fluorescence)

  16. 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 (<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.

  18. BONUS SLIDE

  19. 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

  20. 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 Xmaxfor fluorescence events Xmaxfor Golden events

  22. Energyreconstruction Y : Fluorescence yield (ph/m) Kakimoto Model η : Atmosphere transmission Lowtran Model ε : Detector efficiency ΔΩ : Detector solid angle

  23. Energyreconstruction

  24. 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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