The EVA code Macroscopic modeling of radio emission

The EVA code Macroscopic modeling of radio emission based on full MC simulations including a realistic index of refraction Krijn de Vries ¹ Olaf Scholten ¹ Klaus Werner ² KVI/RUG Groningen ¹ SUBATECH, University of Nantes ²

Radio Emission Mechanisms: Geo-Magnetic current § e+e- pairs are deflected in the Earth Magnetic Field due to the Lorentz force. § Net macroscopic current in the direction of the Lorentz force. 1

Radio Emission Mechanisms: Charge excess § Several processes give rise to a net negative charge of the shower front (Askaryan): 1. Compton scattering 2. Knock out by shower particles 3. Positron annihilation § Net negative current in the direction of movement of the shower. 2

MGMR vs EVA Ingredients: Particle distributions and Currents § MGMR: § EVA: - Parameterized current - Full Monte Carlo and charge distribution simulations - Lateral particle extent ignored. - Full 3 D shower information from histograms. - No Cherenkov effects - Cherenkov effects included. 3

The EVA code § CX-MC-GEO: Full Monte Carlo version of CONEX - Provides histograms of the current and charge distributions § FITMC: Fit program - Provides analytical expressions for the currents and particle distribution. § EVA: Coherent radio emission from current and charge distributions - Including Cherenkov effects 4

CX-MC-GEO+MCFIT: The shower profile Ne(t’) Fit Histo Shower time t’(μs) K. Werner, et. al. ar. Xiv: 1201. 4471 5

Jz/Nec Jx, y/Nec CX-MC-GEO+MCFIT The Macroscopic currents Shower time t’(μs) Geomagnetic Current K. Werner, et. al. ar. Xiv: 1201. 4471 Fit Histo Shower time t’(μs) Charge-excess Current 6

CX-MC-GEO+MCFIT: The particle distributions in the shower front mm scales !! K. Werner, et. al. ar. Xiv: 1201. 4471 7

CX-MC-GEO+MCFIT: The particle distributions in the shower front Lateral particle distribution in the pancake: Longitudinal particle distribution close to the shower axis, very sharp!!! <r>=1. 3 m Fit Histo 1 cm r(m) K. Werner, et. al. ar. Xiv: 1201. 4471 h(m) 8

EVA - Emission Mechanisms From Currents to radiation. D can vanish for realistic cases, n = n(z) ≠ 1 Cherenkov ! 9

EVA - Retarded distance t': emission time t: observer time -t’(μs) Ne· 10 -11 t(μs) 10

EVA - The Atmosphere and index of refraction - The atmosphere is given by the law of Gladstone -t’(μs) - Ray tracing possible, shown to be not important. - The refractivity is given 60° b = 100 m t(μs) -t’(μs) by the US standard atmosphere. SL Curved 90° b = 100 m And Dale: t(μs) 11

EVA - The Electric Field Cherenkov effects Square-root divergence, can be safely integrated for smooth currents and weight functions! Cherenkov effects can be included due to the finite extent of the shower front!!!!!! 12

EVA vs MGMR 800 meters 0. 5 E(μV/m) 0. 5 EVA n = 1 0. 2 EVA n = n(z) -1. 5 0 t(μs) E(μV/m) -1. 5 t(μs) 0 3 MGMR n = 1 L=2 m -1. 5 0 t(μs) 3 13

EVA vs MGMR 100 meters 500 EVA n = 1 100 0 t(μs) EVA n = n(z) -4500 E(μV/m) -900 E(μV/m) 100 t(μs) 0 0. 05 MGMR n = 1 L=2 m -500 0 t(μs) 0. 05 14

EVA vs MGMR 0. 5 E(μV/m) 500 -4500 0 t(μs) d=100 meters 0. 05 0 t(μs) 3 d=800 meters 15

The EVA package: To obtain the EVA package, please contact Krijn de Vries by sending an e-mail to dvries@kvi. nl 16

Conclusions § The EVA package is developed: - The code is based on Full Monte Carlo air shower simulations - Cherenkov effects can be included due to finite extent of the current distributions (particles in the shower front) § Differences between EVA and MGMR are due to the shower front and Cherenkov effects § MGMR works good at large observer distances: Advantage fast! § The EVA package is public! 17

The EVA package: To obtain the EVA package, please contact Krijn de Vries by sending an e-mail to dvries@kvi. nl 16

General Pulse Shape Cherenkov distance: Sharp edge of shower front Particle max Far from the Cherenkov distance: Shower profile pre shower max Shower max 12