First results from EVA simulations

Krijn de Vries ¹Olaf Scholten ¹Klaus Werner ²

¹ KVI/RUG Groningen ² SUBATECH, University of Nantes

ARENA 2012 1

Timing Radio pulse

Distant & near emission may arrive simultaneously

n=1 !!Most distant emission arrives first

Arrives later

n=real

z = ct’

c

c

z = ct’c/n

c/n

Large, sharp pulset = d2/2czARENA 2012 2

EVA - Emission MechanismsFrom Currents to radiation.

dt'dtR=

θnβR=Dt,xDt'J=t,xA

μμ

cos1||

t,xAxddt,xA

dtd

=t,xE

0

D can vanish for realistic cases,n = n(z) ≠ 1 Cherenkov !

'

)'(),()'(),( ||

14

20

dttdJhrwtJ

dhhrdw

Ddhrdc=t,xE PL

x

PLxx

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The extreme case for a realistic shower front

50

20

1D= 1Rdt'dt

Shower profile

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The extreme case for a realistic shower front

50

20

Arrival times reflected in pulse shapes

1D= 1Rdt'dt

Shower profile

E/10!!

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De Vries et al., PhysRevLett. 107, 061101 (2011),Alvarez-Muñiz et al., arXiv:1107.1189

n=realistic

A-typical example

5

EVA: Realistic shower frontHigh Frequencies!!

/10

Sharp pulse High frequency > 1GHz

shower max@30 km (along sh axis)impact = 400 m, E=5x1017eV

E(μV

/m/M

Hz)

E(m

V/m

)

t(ns)

ν(MHz)

d=1170 mn=1n=n(z)n=1.0003

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Length Scales Cherenkov: Shower front; cm or GHz

Normal: derivative of the projected shower

profile; m or 10 MHz

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270 shower

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1 GHz v.s. 10 MHz

0.1 ns v.s. 10 ns

Cherenkov v.s.‘normal’

EASIER ?

100100

100 m 400 m

Frequency spectrum

1000100 10010

Time spectrum

Timing !

8

Cherenkov effects; Probing the shower profile

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No Cherenkov

Cherenkovdominant

Cherenkov + ‘normal’

b>300 m

b=250 m

b<200 m9

θ = 60o, E=1017 eV

-200

-7000

-3000

~ 60 ns

~ 4 ns

~ 8 ns

E(μV

/m)

E(μV

/m)

E(μV

/m)

t(μs)

t(μs)

t(μs)ARENA 2012 10

No Cherenkov

Cherenkovdominant

Cherenkov + ‘normal’

b>300 m

b=250 m

b<200 m

Cherenkov effects; Pulse in time

Two bump structure for Cherenkov emission from below the shower maximum!!

E(μV

/m/M

Hz)

10 100ν(MHz)

1000 50000.1

3

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No Cherenkov

Cherenkovdominant

Cherenkov + ‘normal’

b>300 m

b=250 m

b<200 m

Cherenkov effects; Pulse in frequency

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!

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The LDF: Determining the Chemical composition

Chernkov ring clearly visible, becomes sharper at high frequencies!

Link position d_max to emission height by:

122max

n

dzc

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determined by X_max

Polarization of the radio emission:Determining the Charge excess in the Air

Shower

Geomagnetic: Charge excess (Askaryan):

Leading: Geomagnetic

Sub Leading: Charge Excess

BvdtAdEJA Lorentz

x

00

xd

dAEJA

K.D. de Vries, O. Scholten, K. Werner: Proceedings of the 31th ICRC (2009), Lodz, Poland. ARENA 2012 14

Polarization of the radio emission:Determining the Charge excess in the Air

Shower

eVE

md

p1710

070

)( 22yx

yx

EEEE

R

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Polarization of the radio emission:The charge-excess fraction in the radio

signal

)( 22yx

yx

EEEE

R

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@ N-S

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

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Retarded distance D (2)1D= 1Rdt'dt

2

t': emission timet: observer time

-t’(μs)

t(μs)

Ne·10-11

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Retarded distance D (2)1D= 1Rdt'dt

t': emission timet: observer time

2

-t’(μs)

t(μs)

Ne·10-11

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Retarded distance D (2)1D= 1Rdt'dt

t': emission timet: observer time

2

-t’(μs)

t(μs)

Ne·10-11

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Retarded distance D (2)1D= 1Rdt'dt

t': emission timet: observer time

2

-t’(μs)

t(μs)

Ne·10-11

)( znnctt

)( znnctt

0D

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Sharp edge of shower front

General Pulse shape

Shower max

Cherenkov distance:

Particle max

Far from the Cherenkov distance:

3

Shower profile pre shower max

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Retarded distance D (1)

θnβR=D cos1

nβ=θCH

1cos 1

θ

Observer

1

2

1D

t,xE

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