First results from EVA simulations
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First results from EVA simulations
Krijn de Vries ¹Olaf Scholten ¹Klaus Werner ²
¹ KVI/RUG Groningen ² SUBATECH, University of Nantes
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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
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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
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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 !
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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
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-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
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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
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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
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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
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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
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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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