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) Radio Detection of High Energy Showers Sylvie Dagoret-Campagne GDR Neutrinos, IPN, October, 4 2006.

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Presentation on theme: ") Radio Detection of High Energy Showers Sylvie Dagoret-Campagne GDR Neutrinos, IPN, October, 4 2006."— Presentation transcript:

1 ) Radio Detection of High Energy Showers Sylvie Dagoret-Campagne GDR Neutrinos, IPN, October,

2 GDR Neutrinos, 4-5 october2 History of radio detection of Air Showers Measure by Vernov at al. (1968) Indicating coherence Within a given frequency band But decoherence Appears as frequency increases Spencer (1969) and Allan (1971) Started with Jelley in 1964

3 GDR Neutrinos, 4-5 october3 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 55MHz Normalised pulses For eV

4 GDR Neutrinos, 4-5 october4 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.

5 GDR Neutrinos, 4-5 october5 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»

6 GDR Neutrinos, 4-5 october6 Usual techniques of Air Shower detection

7 GDR Neutrinos, 4-5 october7 Shower development Shower Scaling parameters: In Air: –R m (asl)=70m In Ice: –ρ=0.9g/cm 3 –Rm=13cm –L att (ν)=100m-1km –n= In Rock Salt: –ρ=2g/cm 3 –Rm= –L att (ν)~250m-1km –n=2.45 Lunar regolith (10-20 m depth) –ρ=1.7g/cm 3 –L att (1GHz)=20m –n=1.7 Vertical Air Shower(10 19 eV) Nishimura Kamata Greisen Gaisser Hillas R m : Moliere Radius

8 GDR Neutrinos, 4-5 october8 Radiation of electromagnetic wave by a charged particle Generic solution from retarded potentials Fourier transform of the radiative part Radiative part eV Shower in B earth TF Loss of coherence

9 GDR Neutrinos, 4-5 october9 Energy loss rate Ionisation losses of electrons Cerenkov energy loss Acceleration energy loss

10 GDR Neutrinos, 4-5 october10 Charged Particle Energy loss rate Ionisation losses of electrons Cerenkov energy loss Acceleration energy loss Fluorescence Yield ~ 4 337nm => energetic Yield ~ Cerenkov may Not be neglected In air (air)

11 GDR Neutrinos, 4-5 october11 Example of Radio Cerenkov emission in dense media 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 S rf ~ N elec 2 (coherence, for (λ>R M )) S opt ~ N elec (no coherence, for (λ

12 GDR Neutrinos, 4-5 october12 Acceptance Radio vs Optical Cerenkov in Ice for ν induced Showers N det =V eff σ νN nΦ ν εΩT N det : nb ν detected V eff : effective detection volume σ νN : ν-nucleon cross section n : target density Φν : Neutrino flux ε detection efficiency Ω : solid angle of detection T : Time

13 GDR Neutrinos, 4-5 october13 Cerenkov emission in Showers 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 : (Zas,Hazen, Stanev parameterisation)

14 GDR Neutrinos, 4-5 october14 Frequency dependence : coherence- decoherence transition observed for Cerenkov emission in salt empirical parameterisation: A 0 =2.53x10 -7 V/MHz f d =0.52; δ=1.44 ν 0 =1.15 GHz ν 1 =2.86 GHz hep-ex/ (SLAC test beam)

15 GDR Neutrinos, 4-5 october15 Application of Cerenkov emission in dense Media to High Energy Cosmic Neutrinos I

16 GDR Neutrinos, 4-5 october16 Radio emission detectors (Antenna and Horns) dedicated to neutrino shower detection (US) FORTE ν shower detection in Greenland Ice Log periodic antenna, MHz A=10 5 km GLUE/Goldstone 99: ν shower detection In Lunar regolith L and S band (about 2 GHz) A= km ANITA: End 2006 ν shower detection In Antartica Ice 200 MHz GHz A=10 4 km

17 GDR Neutrinos, 4-5 october17 Application of Cerenkov emission of ν induced Showers in Ice or atmopshere: Pioneering radio experiments (FORTE)

18 GDR Neutrinos, 4-5 october18 Example of Forte neutrino candidate Frequency channel time Signal : wide band, during few ns Background : one frequency Long duration.

19 GDR Neutrinos, 4-5 october19 Target volume for radio detection: 2 x 10 5 (km.w.e ) 3 Application of Cerenkov emission in the Lunar Regolith to detect High Energy Cosmic Neutrinos

20 GDR Neutrinos, 4-5 october20

21 GDR Neutrinos, 4-5 october21 Application of Cerenkov emission of ν induced Showers in Ice : The anita Concept

22 GDR Neutrinos, 4-5 october22 SALSA

23 GDR Neutrinos, 4-5 october23 SALSA 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 live GZK neutrino events

24 GDR Neutrinos, 4-5 october24 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 live GZK neutrino events Salsita: 4 strings 3 events per year Salsita 3 years

25 GDR Neutrinos, 4-5 october25 Geo Synchrotron process in Air Showers single particle-> Formula used in particle Shower Monte Carlo like Aires

26 GDR Neutrinos, 4-5 october26 Frequency spectrum emission by a charge accelerated in a circular motion But how can we take into account Coherence / decoherence effect vs Frequency ? To measure the energy ! Formula used in Analytic estimates Of Synchrotron emission

27 GDR Neutrinos, 4-5 october27 Radio emission detectors (Antenna and Horns at ground) Codalema dipole (Nancay) Codalema log periodic Antenna (Nancay) Lopes V antenna (KASCADE) AMBER Horn (Hawai)

28 GDR Neutrinos, 4-5 october28 Codalema What is the Radio LDF ? dependence on incident angles Frequency dependence Antenna directivity Relation to energy (coherence)

29 GDR Neutrinos, 4-5 october29 Some Codalema measurements RLDF for the most Spread events Mean voltage vs Frequency V(ν)~ Kν (1-a) 1-a exponent vs distance Astro-ph

30 GDR Neutrinos, 4-5 october30 Molecular Bremstrahlung 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:

31 GDR Neutrinos, 4-5 october31 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)

32 GDR Neutrinos, 4-5 october32 This technique may also be used for air profile Shower measurement,… to be proved

33 GDR Neutrinos, 4-5 october33 Radar detection principle

34 GDR Neutrinos, 4-5 october34 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 of the ionised electron density It is proportional to |n e (r)d 3 r| 2 At low frequency σ T =0.665x cm 2

35 GDR Neutrinos, 4-5 october35 Rappels de la théorie de la diffusion (Jackson 2001, chapitre 10): –Section efficace différentielle de diffusion d’un champs oscillant sur une collection de centres diffuseurs (approximation de la contribution dipolaire électrique seulement): – ε vecteur polarisation du signal radar, – p moment dipolaire des centres diffuseurs, –q moment transfere : q=kn 0 -k’n –E 0 champs électrique incident La section efficace Radar (RCS) se déduit de la densité d’ionisation de l’air (dans l’approximation sous-dense c’est à dire f radar > ν plasma ) La RCS de la gerbe est la transformée de Fourier (3D) de la densité d’ionisation La densité d’ionisation totale est proportionnelle à l’énergie de la gerbe. Calcul de la section efficace de diffusion Radar de l’objet Gerbe σ T =0.665x cm 2

36 GDR Neutrinos, 4-5 october36 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

37 GDR Neutrinos, 4-5 october37 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

38 GDR Neutrinos, 4-5 october38 Small, overdense meteor, of approximately 0.8s duration. One long and two small underdense meteors. Data taken with MHz (ch 4) - Pittsburgh Station (from H. Takai, ANL and Brookhaven) ~ 500 km Radar routinely used for Meteor detection

39 GDR Neutrinos, 4-5 october39 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

40 GDR Neutrinos, 4-5 october40 Blue Dots are Nearest CH 4 TV Stations, 67.25Mhz -10Khz +10Khz 0Khz ANL and Brookhaven groups

41 GDR Neutrinos, 4-5 october41 Frequency Spectrum vs Time in Argonne System: Airplanes and Meteors Time Frequency Meteors Airplanes

42 GDR Neutrinos, 4-5 october42 Now proof must establish the connection of Air Shower detection with short time (few ns) Radar echo

43 GDR Neutrinos, 4-5 october43 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

44 GDR Neutrinos, 4-5 october44 Validation of Askarian effect Coherent Radio Cerenkov in sand and salt NIM A490 (2002) 476 astro-ph/ Proof of coherence ? Must show a frequency Cutoff !

45 GDR Neutrinos, 4-5 october45

46 GDR Neutrinos, 4-5 october46 Molecular Bremstrahlung

47 GDR Neutrinos, 4-5 october47 Molecular Bremstrahlung in Test Beam June 2003 July 2004

48 GDR Neutrinos, 4-5 october48 Search of Molecular Bremstrahlung at SLAC Proof of coherence ? Measure of e lifetime ? 60 ns ?

49 GDR Neutrinos, 4-5 october49 Résultats sur le bremstrahlung moléculaire Pas de publication jusqu’à présent À verifier !

50 GDR Neutrinos, 4-5 october50 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)

51 GDR Neutrinos, 4-5 october51 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 0.20 m antenne

52 GDR Neutrinos, 4-5 october52 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 Faiscea u radar Antenne réceptric e 1m 0.20 m Chambre non métallique pour faire varier la pression Antenne monitori ng

53 GDR Neutrinos, 4-5 october53 3.Test de coherence sur le rayonnement synchrotron B=10 G (20 x B terre ) E crit = γ e 2 B(T) = eV R curv = 3E(GeV)/B(T) =30m ν crit =67GHz λ crit =4.5mm Dipole magnétique ( Gauss) Electron 10 MeV Photon synchrotron détecteur 5m 3m

54 GDR Neutrinos, 4-5 october54 Théorie de la cohérence du rayonnement synchrotron The physics of synchrotron radiation (Albert Hofmann,2004): –N e, nombre d’électrons dans le paquet –σ T largeur temporelle du faisceau (σ s =cσ t ) – ω pulsation

55 GDR Neutrinos, 4-5 october55 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

56 GDR Neutrinos, 4-5 october56 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,

57 GDR Neutrinos, 4-5 october57 backup

58 GDR Neutrinos, 4-5 october58 Air index

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