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First results from EVA simulations

First results from EVA simulations. Krijn de Vries ¹ Olaf Scholten ¹ Klaus Werner ² ¹ KVI/RUG Groningen ² SUBATECH , University of Nantes. Timing Radio pulse. n=real. n=1 !!. Most distant emission arrives first. c/n. z = ct’. z = ct’.

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First results from EVA simulations

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  1. First results from EVA simulations Krijn de Vries¹ Olaf Scholten¹ Klaus Werner ² ¹ KVI/RUG Groningen ² SUBATECH, University of Nantes

  2. Timing Radio pulse n=real n=1 !! Most distant emission arrives first c/n z = ct’ z = ct’ Distant & near emission may arrive simultaneously c c Arrives later c/n t = d2/2cz Large, sharp pulse

  3. EVA - Emission MechanismsFrom Currents to radiation. D can vanish for realistic cases, n = n(z) ≠ 1  Cherenkov !

  4. The extreme case for a realistic shower front 50 Shower profile 20

  5. The extreme case for a realistic shower front A-typical example n=realistic E/10!! 50 Shower profile Arrival times reflected in pulse shapes 20 De Vries et al., PhysRevLett. 107, 061101 (2011), Alvarez-Muñiz et al., arXiv:1107.1189

  6. EVA: Realistic shower frontHigh Frequencies!! Sharp pulse  High frequency >1GHz E(mV/m) E(μV/m/MHz) /10 d=1170 m n=1 n=n(z) n=1.0003 t(ns) shower max@30 km (along sh axis) impact = 400 m, E=5x1017eV ν(MHz)

  7. Length Scales • Cherenkov: • Shower front; cm or GHz • Normal: • derivative of the projected shower profile; m or 10 MHz

  8. 270 shower 100 m 400 m Cherenkov v.s. ‘normal’ Timing ! 0.1 ns v.s. 10 ns Time spectrum Frequency spectrum 1 GHz v.s. 10 MHz EASIER ? 100 100 1000 10 100 100

  9. Cherenkov effects; Probing the shower profile No Cherenkov b>300 m Cherenkov dominant b=250 m Cherenkov + ‘normal’ θ = 60o, E=1017eV b<200 m

  10. Cherenkov effects; Pulse in time E(μV/m) ~ 60 ns -200 t(μs) No Cherenkov b>300 m E(μV/m) ~ 4 ns Cherenkov dominant -7000 t(μs) b=250 m E(μV/m) Cherenkov + ‘normal’ ~ 8 ns b<200 m -3000 t(μs)

  11. Cherenkov effects; Pulse in frequency 3 No Cherenkov b>300 m E(μV/m/MHz) Cherenkov dominant b=250 m 0.1 10 100 1000 5000 Cherenkov + ‘normal’ ν(MHz) Two bump structure for Cherenkov emission from below the shower maximum!! b<200 m

  12. Two bump structure seen at ANITA? Simulation for 60 degrees shower at the Auger site. Geometry of ANITA event not known, so not 1 to 1 comparable!

  13. The LDF: Determining the Chemical composition Chernkov ring clearly visible, becomes sharper at high frequencies! Link position d_max to emission height by: determined by X_max

  14. Polarization of the radio emission:Determining the Charge excess in the Air Shower Leading: Geomagnetic Sub Leading: Charge Excess Geomagnetic: Charge excess (Askaryan): K.D. de Vries, O. Scholten, K. Werner: Proceedings of the 31th ICRC (2009), Lodz, Poland.

  15. Polarization of the radio emission:Determining the Charge excess in the Air Shower

  16. Polarization of the radio emission:The charge-excess fraction in the radio signal @ N-S

  17. Conclusions Cherenkov effects lead to emission at very high frequencies > 1GHz Cherenkov emission below the shower maximum gives rise to a two bump structure in the frequency spectrum The Cherenkov ring gives information about the shower maximum The fraction of charge-excess in the radio signal is affected by Cherenkov effects and not constant

  18. Retarded distance D (2) Ne·10-11 t': emission time t: observer time -t’(μs) t(μs) 2

  19. Retarded distance D (2) Ne·10-11 t': emission time t: observer time -t’(μs) t(μs) 2

  20. Retarded distance D (2) Ne·10-11 t': emission time t: observer time -t’(μs) t(μs) 2

  21. Retarded distance D (2) Ne·10-11 t': emission time t: observer time -t’(μs) t(μs) 2

  22. General Pulse shape Far from the Cherenkov distance: Cherenkov distance: Sharp edge of shower front Shower profile pre shower max Particle max Shower max 3

  23. Retarded distance D (1) Observer 1

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