radio detection of high energy showers
DESCRIPTION
). Radio Detection of High Energy Showers. Sylvie Dagoret-Campagne GDR Neutrinos, IPN, October, 4 2006. History of radio detection of Air Showers. Started with Jelley in 1964. But decoherence Appears as frequency increases Spencer (1969) and Allan (1971). - PowerPoint PPT PresentationTRANSCRIPT
GDR Neutrinos, 4-5 october
)Radio Detection of High Energy Showers
● Sylvie Dagoret-CampagneGDR Neutrinos, IPN, October, 4 2006
GDR Neutrinos, 4-5 october 2
History of radio detection of Air Showers
Measure by Vernov at al. (1968)Indicating coherenceWithin a given frequency band
But decoherenceAppears as frequency increasesSpencer (1969) and Allan (1971)
• Started with Jelley in 1964
GDR Neutrinos, 4-5 october 3
What can we conclude from a Radio Lateral density Function (RLDF)
• Dependence with– Frequency,– Incident angle,
• Relation to primary energy ?
From Allan (1971)Frequency at 55MHzNormalised pulsesFor 1017eV<E<1019eVθ<30°
Allan,H.R, Havera Park (44 MHz,60MHz) ?
GDR Neutrinos, 4-5 october 4
Main questions still open
• Can Radio detection measure the Shower energy ?
• Can Radio detection identify the nature of the Cosmic rays ?
• In the 70’s Radio detection where abandoned in favour of – Particle detection at the ground (scintillators or Cerenkov water
rank),– Then Cerenkov emission was used (pointing on identified
photon sources)– Later in the 90’s the Fluorescence detection was used.
GDR Neutrinos, 4-5 october 5
Content
• Usual detection method of Air Showers• Radio emission process
– Cerenkov emission,– Synchrotron emission,– Bremstrahlung emission,– Transition radiation,
• Radar detection• The question of the coherence,• Current experiment in radio detection
– Radio Cerenkov experiments for neutrino detection,– Air Shower Radio detection,
• Test beam experiments that should be done• Radio « detectors»
GDR Neutrinos, 4-5 october 6
Usual techniques of
Air Shower detection
GDR Neutrinos, 4-5 october 7
Shower developmentShower Scaling parameters:• In Air:
– Rm(asl)=70m
• In Ice:– ρ=0.9g/cm3
– Rm=13cm
– Latt(ν)=100m-1km
– n=1.3 - 1.8• In Rock Salt:
– ρ=2g/cm3
– Rm=
– Latt(ν)~250m-1km
– n=2.45• Lunar regolith (10-20 m depth)
– ρ=1.7g/cm3
– Latt(1GHz)=20m
– n=1.7
Vertical Air Shower(1019eV)
Vertical Air Shower(1019eV)
Nishimura Kamata Greisen
Gaisser Hillas
Rm: Moliere Radius
GDR Neutrinos, 4-5 october 8
Radiation of electromagnetic wave by a charged particle
• Generic solution from retarded potentials
• Fourier transform of the radiative part
c
tEntB
ncr
nn
nr
netE
ret
ret
)()(
).1(
)(
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4)(
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eiE e
ctrti
Radiative part
1019 eVShower inBearth
TF
Loss ofcoherence
GDR Neutrinos, 4-5 october 10
Charged Particle Energy loss rate• Ionisation losses of electrons
• Cerenkov energy loss
• Acceleration energy loss
2max
2max
22
2
2
2
2
/234.02
ln2
cmE
mMeVI
EvmZ
AN
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2min
2max2
nairinmMeVGHz
nc
EZ
nc
EEZ
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Fluorescence Yield ~ 4 γ/MeV @ 337nm => energetic Yield ~ 10-5
Cerenkov mayNot be neglectedIn air
(air)
GDR Neutrinos, 4-5 october 11
Example of Radio Cerenkov emission in dense media
222
222
11
)(
11
)(
ncZ
dX
dNnc
ZddX
dE
•Detected signal in Ice at a given distance (100 m or 500 m)
• Not the same slope vs
Shower energy because coherence appears for radio signal
• Srf ~ Nelec2 (coherence,
for (λ>RM))
• Sopt ~ Nelec (no coherence, for (λ<RM)))
GDR Neutrinos, 4-5 october 13
Cerenkov emission in Showers
trc
qixE
nrc
qxE
ee
eee
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crnticrnti
ikr
)/.(
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In a track step of constant β for a single particle:
The electric field is linearly polarised.
Need charge excess 20 – 30 %:• Compton scattering,•δ rays production,•Positron annihilation,•(Akarian effect)
Contribution inside a Shower :
'
'')).(('3' ),(
),(''
xx
xtJxddt
xE
exxkti
(Zas,Hazen,Stanev parameterisation)
GDR Neutrinos, 4-5 october 14
Frequency dependence : coherence- decoherence transition observed for Cerenkov emission in salt
empirical parameterisation:
1
0
0
1
1
1),,(
TeV
E
R
fARE shd
c
A0=2.53x10-7 V/MHzfd=0.52; δ=1.44ν0=1.15 GHzν1=2.86 GHz
hep-ex/0602043 (SLAC testbeam)
GDR Neutrinos, 4-5 october 15
Application of Cerenkov emission in dense Media to High Energy Cosmic Neutrinos I
GDR Neutrinos, 4-5 october 16
Radio emission detectors (Antenna and Horns) dedicated to neutrino shower detection (US)
FORTE 97-99ν shower detection in Greenland Ice Log periodic antenna,20-300 MHzA=105 km2.sr
GLUE/Goldstone 99:ν shower detectionIn Lunar regolith L andS band (about 2 GHz)A=6.105 km2.sr
ANITA: End 2006ν shower detectionIn Antartica Ice200 MHz - 1.2 GHzA=104 km2.sr
GDR Neutrinos, 4-5 october 17
Application of Cerenkov emission of ν induced Showers in Ice or atmopshere:Pioneering radio experiments (FORTE)
GDR Neutrinos, 4-5 october 18
Example of Forte neutrino candidate
Frequencychannel
time
Signal : wide band, during few nsBackground: one frequencyLong duration.
GDR Neutrinos, 4-5 october 19
Target volume for radio detection: 2 x 105 (km.w.e )3
Application of Cerenkov emission in the Lunar Regolith to detect
High Energy Cosmic Neutrinos
GDR Neutrinos, 4-5 october 20
GDR Neutrinos, 4-5 october 21
Application of Cerenkov emission of ν induced
Showers in Ice : The anita Concept
GDR Neutrinos, 4-5 october 22
SALSA
GDR Neutrinos, 4-5 october 24
Existing Neutrino Limits and Potential Future Sensitivity
• RICE limits for 3500 hours livetime
• GLUE limits 123 hours livetime
• ANITA sensitivity, 45 days total:~5 to 30 GZK neutrinos
IceCube: high energy cascades ~1.5-3 GZK events in 3 years
Auger: Tau neutrino decay events ~1 GZK event per year?
SalSA sensitivity, 3 yrs live70-230 GZK neutrino events
Salsita: 4 strings3 events per year
Salsita 3 years
GDR Neutrinos, 4-5 october 25
ln
BnnnTVmVE
ln
Bnnn
eE
ln
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em
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1
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Geo Synchrotron process in AirShowers
single particle->
Formula usedin particle Shower Monte Carlolike Aires
GDR Neutrinos, 4-5 october 27
Radio emission detectors (Antenna and Horns at ground)
Codalema dipole (Nancay)
Codalema log periodic Antenna (Nancay)
Lopes V antenna (KASCADE)
AMBER Horn (Hawai)
GDR Neutrinos, 4-5 october 28
Codalema
What is the Radio LDF ?• dependence on incident angles•Frequency dependence•Antenna directivity•Relation to energy (coherence)
GDR Neutrinos, 4-5 october 30
Molecular Bremstrahlung
velocityelectronVfrequencycollisionVv
Vv
VvV
c
neV
::)(
)/)((1
)(
24)(
230
3
2
Plasma Emissivity:
•Microwave Molecular Bremsstrahlung Radiation (MBR) in EAS
•Only a small fraction of the available energy budget for secondary isotropic radiation is used up by optical fluorescence.•MBR is simply a subsequent radiative process resulting from the cooling of the EAS plasma.
•The minimum MBR flux can be calculated by considering the emissivity and absorption of a classical bremsstrahlung process.
This process contains a suppression term:
GDR Neutrinos, 4-5 october 31
Principe de détection Radar• Illuminer les
gerbes avec un faisceau radar
• Coïncidence détecteur au sol / signal radar
• Gerbes horizontales (standard a haute altitude, neutrinos a basses altitudes)
GDR Neutrinos, 4-5 october 33
Radar detection principle
GDR Neutrinos, 4-5 october 34
Possibility to measure the longitudinal profile with radar cross section measurement
Ionisation profile density(Aires)
Detection threshold:
The measure of the RCS gives the Fourier transform ofthe ionised electron density
It is proportional to |ne(r)d3r|2
At low frequencyσT=0.665x10-24cm2
GDR Neutrinos, 4-5 october 36
Calculs de Section efficaces Radar de gerbes (provenant de la première zone de Fresnel) (P. Gorham,2001)
• La section efficace a un profil approximativement gaussien de FWHW ~ 30°
50 Mhz
30 Mhz
10 Mhz
angle
radar
GDR Neutrinos, 4-5 october 37
Ionised electron life time measurement
• The electron lifetime at a few km of altitude constrains the possibility of the radar detection
of vertical showers
• This electron lifetime measurement must be checked/measured in a test beam
GDR Neutrinos, 4-5 october 38
Small, overdense meteor, of approximately 0.8s duration.
One long and two small underdense meteors.
Data taken with 67.26 MHz (ch 4) - Pittsburgh Station
(from H. Takai, ANL andBrookhaven)
~ 500 km
Radar routinely used for Meteor detection
GDR Neutrinos, 4-5 october 39
Simple Cheap Radar Detection System
Reflected TV signals from meteors, airplanes, … “Homemade” Dipole Antenna (or any TV antenna)
Commercial Radio Receiver
ANL and Brookhaven groups
GDR Neutrinos, 4-5 october 41
Frequency Spectrum vs Time in Argonne System: Airplanes and Meteors
Time Frequency
Meteors
Airplanes
GDR Neutrinos, 4-5 october 42
• Now proof must establish the connection of Air Shower detection with short time (few ns) Radar echo
GDR Neutrinos, 4-5 october 43
Test Beams to validate Radio detection principles, to prove
coherence principe
• Cerenkov Coherence (Askarian principle)– Used for Neutrino Radio detection
• Geo-Synchotron Coherence/incoherence– Used in Air Shower detection
• Molecular Bremstrahlung– Contribution to Air Shower detection
• Transition Radiation– Contribution to Air Shower detection
• Radar detection
GDR Neutrinos, 4-5 october 44
Validation of Askarian effect Coherent Radio Cerenkovin sand and salt
NIM A490 (2002) 476astro-ph/0412128
Proof of coherence ? Must show a frequencyCutoff !
GDR Neutrinos, 4-5 october 46
MolecularBremstrahlung
GDR Neutrinos, 4-5 october 48
Search of Molecular Bremstrahlung at SLAC
Proof of coherence ?Measure of e lifetime ? 60 ns ?
GDR Neutrinos, 4-5 october 50
Tests in an electron Beam we would like to do at LAL or IPN to check the Radio emission
• Check of Coherence in Synchrotron emission in a dipole magnetic field,– Coherence never clearly established neither in a circular nor linear
accelerator
– Correction for Transition radiation backscattered at ground ?
• Check the molecular bremstrahlung and measure the electron lifetime in the ionised plasma,– Check results from SLAC test beam results
• Detect the radar echo of the electron beam,– Predicted since a long time, never proved,
• Calibrate our instrumentation using Cerenkov emission in a dense material – (coherence assumed at these frequency)
VHF measure are quite unusual in HEP experiments,Benefit from new technologies (Fast Oscilloscope, FADC above GHZ)
GDR Neutrinos, 4-5 october 51
1.Test de l’existence du Bremstrahlung Moleculaire
• Le passage des electrons dans l’air cree un plasma,
• Les electrons ionises du Plasma induisent une emission RF appelee bremstrahlung thermique (en astro) ou moleculaire.
• Le but est de mesurer la duree de vie de colonne d’ionisation, voir de verifier sa densite spectrale
d’emission.
Taille du faisceau variable
1m
0.20m
antenne
GDR Neutrinos, 4-5 october 52
2.Test de la diffusion radar
• Le passage des electrons dans l’air cree un plasma
• On essaye de determiner la duree de vie des electrons du plasma en etudiant la forme temporelle de l’echo radar.
• On mesure la section efficace de diffusion Radar
Taille du faisceau variable
Faisceau radar
Antenne réceptric
e
1m
0.20m
Chambre non métallique pour faire varier la
pression
Antenne monitori
ng
GDR Neutrinos, 4-5 october 53
3.Test de coherence sur le rayonnement synchrotron
• B=10 G (20 x Bterre)• Ecrit=1.1 10-4 γe
2 B(T) = 4.5.10-5 eV• Rcurv= 3E(GeV)/B(T) =30m• νcrit=67GHz• λcrit=4.5mm
Dipole magnétique (10-100 Gauss)
Electron 10 MeV
Photon synchrotron
détecteur
5m
3m
GDR Neutrinos, 4-5 october 55
Coherence never really established
At which frequency this transition occurs ?
Contribution of beam sub-structures ?
Radio Synchrotron spectrum that should be measured with its coherence /decoherence transition
3/44 /5257.0
s
e
incoherent
coherent NPP
GDR Neutrinos, 4-5 october 56
Conclusion• There is a wide interest to detect Showers with radio :
– 100 % duty cycle (10 x Fluorescence aperture)– Antenna may be cheaper than Photomultipliers,– Larger acceptance for neutrino detection due to longer
attenuation range,• But one has to prove we can do Air shower measurement with RF
as well as standard techniques:– Energy measurement,– Primary identification,
• Some fundamental questions must be answered like,– Main physical processes involved in radio emission by shower
electrons, Cerenkov radiation, Transition radiation, Synchrotron,– Ionised plasma physics vs altitude and atmospheric composition,
atmospheric condtions (p,T) must be understood, (Bremstrahlung,Radar)
– Coherence effect vs frequency,• Calibration techniques must be found,
GDR Neutrinos, 4-5 october 57
backup
GDR Neutrinos, 4-5 october 58
Air index
6
2
5
10108.311)(79
1TTT
mbarpn