1. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Pierre 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… )

2. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Purpose: Reconstruct initial UHECR parameters Energy (spectrum) Direction (UHECR sources map) Particle type (proton, iron, neutrino, gamma, etc.) Physics hopes ?

3. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Angles (Zenithal θ and Azimuthal φ) Altitude of shower maximum: H max Depth of shower maximum: X max Total energy released E Shower parameters H max X max UHECR : Direction Particle type Energy E

4. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 UHECR Detection from space Extensive air shower Air fluorescence (isotropic) Space telescope Cerenkov light (directional) Ground scattering Cloud EUSO simulation Fluorescence Cerenkov echo SIGNAL = f(t)

5. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Data fit fit: 2 Gaussians: Fluorescence + Cerenkov + constant: Background noise Monte Carlo data - Global fit Fluorescence Cerenkov Background Available information: for every GTU (Time Unit ~2.5 µs) Number of detected photons: N i

6. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Reconstruction Get angles (θ,φ) Get H max Get X max Get E Monte Carlo Data Signal analysis (Trigger conditions): 3 samples of events Fluorescence events Cerenkov events Golden events (Fluo+Cer) Reconstruction Get angles (θ,φ) Get H max Get X max Get E TWO METHODS Key parameter Golden event Fluorescence event Need Cerenkov echo Only signal shape

7. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 H max reconstruction : Cerenkov method For golden events : We use Cerenkov echo : Time between Cerenkov and fluorescence maximum (Classical method) Disadvantage: We need to know H cer to reconstruct H max : Relief, Cloud altitude (Lidar?) x y z EUSO α ΔH Cerenkov echo Fluorescence R ΔH = H max - H cer ΔH H max = ΔH + H cer

8. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 H max reconstruction : Cerenkov method Method not efficient for large angle (horizontal EAS) Test of the method: no cloud events (H cer = 0 ) Reconstructed H max vs Simulated H max Relative Erreur Error<10% for <60°

9. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 (Brand new method) For Fluorescence event: H max reconstruction : Shape method Fluorescence Yield (ph/m) We use only Fluo signal L = EAS track length = # emitted photon N e = # charged particles in EAS Y = Fluorescence Light Yield Y: smooth variation with altitude In one GTU i: L i = L GTU N i η·Y·N e · L GTU = # detected ph/GTU N i is quite independent of the altitude: N i N e N max (η·Y) max ·N e max · L GTU Transmission η has also a smooth variation with altitude

10. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Total shower lenght: L = L GTU = x tot / (h) N tot = N i η·Y· ·L η·Y· · x tot / (h) X tot = L · (h) L 20 =100 km H max reconstruction : Shape method L 5 = 15 km 5 km20 km For horizontal showers: N tot varies dramatically with altitude :

11. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 H max reconstruction : Shape method Approximation: = (η·Y) max · = (H max ) Generalization for all angles : (H max ) H max N max /N tot (H max ) Thanks to η & Y smooth variation with altitude Varies like ln(E)

12. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 H max reconstruction : Shape method Good Method to reconstruct large angle EAS ! Reconstructed vs Simulated H max Relative Erreur Test of the method: Error 60°

13. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Simulated Direction reconstruction : There is relationship between ( i x, i y ) and (θ,φ) angle of EAS. Reconstruct Assuming infinite pixel resolution Reconstruct Θ Available information: for every GTU Photon incident angles: i x, i y Direction: σ ~ 2°

14. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 X max reconstruction (reconstructed X max – simulated X max ) (Θ) in g/cm2 H max by Cerenkov echo H max by shape method σ <5% for <50° σ ~ 10 % Golden eventsfluorescence events

15. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Energy reconstruction E reconstructed by shape method (fluorescence) for 10 20 eV proton σ = 22%

16. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Shape method good for UHE neutrinos! protons neutrinos Neutrinos create mainly horizontal EAS without Cerenkov echo.

17. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Conclusion We can reconstruct any EAS : 0° to 90° or more ! This first trial is very promising. 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

18. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 BONUS SLIDE

19. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Simulated data Available information: for every GTU (Time Unit ~2.5 µs) Photon incident angles: i x, i y Number of detected photons: N i x y z Space telescope αxαx αyαy Extensive air shower H max i x, i y EUSO simulation

20. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 If we add pixel resolution: EUSO event on focal plan (M36) Error : more from detector than from method EUSO simulation

21. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Ironproton SLAST simulation of X max (g/cm2) X max reconstruction X max change with RCUE type: X max = f(E/A) (E/A is energy by nucleon) X max for Golden events X max for fluorescence events Test with 10 000 protons and 10 000 iron nuclei

22. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Energy reconstruction Y : Fluorescence yield (ph/m)Kakimoto Model η : Atmosphere transmissionLowtran Model ε : Detector efficiency ΔΩ : Detector solid angle

23. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 Energy reconstruction

24. XXXX eme Rencontres de Moriond Pierre COLIN March 2005 UHECR Air scattering Detection from space Extensive air shower Air fluorescence (isotropic) Space telescope Cloud Cerenkov light (directional) Ground scattering EUSO simulation SIGNAL = f(t)