1. 3rd France China Particle Physics Laboratory Workshop 07 April 2010 – 09 April 2010, IPNL, Lyon, France CosmicRays@21CMA : Update and latest results NAOC : Saugrin T. Wu X. Zhao M. IHEP : Gou Q. Hu H. Martineau-Huynh O. Xie Y. Zhang J. SUBATECH : Ardouin D. Charrier D. Lautridou P. Ravel O. LPC : Niess V.

2. RADIODETECTION : EXPERIMENTAL STATUS Particle triggered experiment results (CODALEMA, LOPES) : Radiodetection is a very promising technique for EAS detection and studies : Cheaper than usual techniques : very large arrays are possible ! Sensible to very inclined showers : good for neutrinos detection ! Proof of feasibility Evidence for geomagnetic orgin of the EAS radio signal Experimental dataGeomagnetic simulation CODALEMA North – South asymmetry at the lowest energy (< 10 18 eV) Signature for a preponderant geomagnetic effect in the radio signal creation mechanism

3. RADIODETECTION : EXPERIMENTAL STATUS Particle triggered experiment results (CODALEMA, LOPES) : Radiodetection is a very promising technique for EAS detection and studies : Cheaper than usual techniques : very large arrays are possible ! Sensible to very inclined showers : good for neutrinos detection ! Proof of feasibility Evidence for geomagnetic orgin of the EAS radio signal Energy calibration CODALEMA Linear relation between energy radio estimation and particle detector estimation EAS energy reconstruction is possible with radiodetection !

4. Particle triggered experiment results (CODALEMA, LOPES) : Radiodetection is a very promising technique for EAS detection and studies : Cheaper than usual techniques : very large arrays are possible ! Sensible to very inclined showers : good for neutrinos detection ! Proof of feasibility Evidence for geomagnetic orgin of the EAS radio signal Energy calibration RADIODETECTION : EXPERIMENTAL STATUS To detect efficiently Ultra High Energy Cosmic Rays (UHECRs) or high energy neutrinos, we need very large arrays independent of any external trigger ! It’s time for autonomous radiodetection experiments : CODALEMA3, AERA and … CRs@21CMA!

5. DAQ CosmicRays@21CMA 4 km 3 km 21CMA is a giant radiotelescope located in the Tianshan Mountains (Xinjiang) Built in 2007 by NAOC (WU X.-P.) to study the epoch of re-ionization North East West South 10160 log-periodic antennas (signal phased by pod of 127) Each pod is linked to the acquistion room by optical fiber Signal acquisition performed by 200 MHz ADC

6. CosmicRays@21CMA The CosmicRays@21CMA : Quickly set up an independent autonomous EAS radiodetection array based on the 21CMA : Antennas Electronics Acquisition system + + Scientific objectives: Radiodetection unique ability to detect very inclined EAS Ulastai spatial characteristics : Valley surrounded by high mountains Isolated area (very low EM noise) First radiodetection experiment dedicated to neutrino detection !

7. FIRST PHASE (2009) : SET UP From January 2009 to December 2009 : Prototype of 6 antennas on the East-West arm Independent acquisition channel for each antenna Coincidences have to be found offline ! Frequency bandwidth limited to 50 – 100 MHz ( Optical transmitter (50-200 MHz) and 200 MHZ sampling ADC) Signal amplification 64 dB Signal filtering 50 – 100 MHz Optical transmitter Optical receiver Signal digitization 200 MHz ADC AntennaAntenna board Acquisition room … Coaxial cable Optical fiber

8. FIRST PHASE (2009) : SET UP From January 2009 to December 2009 : Prototype of 6 antennas on the East-West arm Independent acquisition channel for each antenna Coincidences have to be found offline ! Frequency bandwidth limited to 50 – 100 MHz ( Optical transmitter (50-200 MHz) and 200 MHZ sampling ADC) σ N.σ Signal recorded for Max signal > N. σ First Level Trigger :

9. FIRST PHASE (2009) : PERFORMANCES Galactic plane sensitivity : Thermal emission from galactic plane Minimum possible noise for a radio detector Maximal in the North hemisphere between 15h and 23h LST Galactic plane @ 408 MHz CODALEMA: 6 months data averaging on one antenna CRs@21CMA: Superposition of 14 days of background data on one antenna CRs@21CMA sensitivity is well suited to EAS radiodetection !

10. FIRST PHASE (2009) : PERFORMANCES Galactic plane sensitivity : Thermal emission from galactic plane Minimum possible noise for a radio detector Maximal in the North hemisphere between 15h and 23h LST Galactic plane @ 408 MHz CRs@21CMA sensitivity is well suited to EAS radiodetection ! CODALEMA: 6 months data averaging on one antenna CRs@21CMA: Superposition of 14 days of background data on one antenna

11. Spherical reconstruction quality : FIRST PHASE (2009) : PERFORMANCES Δ SN ~ 1.6 m & Δ WE ~ 1.5 m Position of a known static source (engine) well reconstructed

12. FIRST PHASE (2009) : PERFORMANCES Work also well for moving sources at ground level ike trains … Train track Spherical reconstruction quality :

13. FIRST PHASE (2009) : PERFORMANCES Spherical reconstruction quality : … or moving sources in the sky like planes But what about EAS ?

14. RADIO SIGNAL FEATURES e+e+ e-e- Geomagnetic force Geomagnetic coherent emission from shower electrons / positrons Short pulse duration (a few hundreds of nanoseconds) Quasi-plane EM wave (high emission point) Exponential dependence of the amplitude with the distance to the shower axis : CODALEMA Empirically measured in the 70’s Verified by present radiodetection experiments E(d) α E P. exp(-d/d 0 ) E P : shower energy d 0 : attenuation parameter (typical value ~ 200m)

15. RADIO SIGNAL FEATURES EAS radio signalLocal and temporary noise source Signal waveformShort pulse (<500 ns)Variable (mostly long pulse) Arrival directionIsotropicMostly along the horizon (pointing in the source direction) Time distributionIsotropicMostly bursts Wave reconstructionPlaneSpherical (close sources) Amplitude1/exp(d)1/r

16. NOISE REJECTION PROCEDURE Signal shape ? (signal waveform and duration)

17. NOISE REJECTION PROCEDURE Signal form (signal form and duration) Quiet period ? (no radio noise burst)

18. NOISE REJECTION PROCEDURE Signal form (signal form and duration) Quiet period ? (no radio noise burst)

19. NOISE REJECTION PROCEDURE Signal form (signal form and duration) Quiet period (no radio noise burst) Reconstruction quality of arrival direction? Zenith angle limitation (ϴ < 60°) ?

20. NOISE REJECTION PROCEDURE Signal form (signal form and duration) Quiet period (no radio noise burst) Reconstruction quality of arrival direction? Zenith angle limitation (ϴ < 60°) Comparison plane/spherical reconstruction ? Expected delays : Expected wave detection time (on each antenna) with the reconstructed arrival direction

21. NOISE REJECTION PROCEDURE Signal form (signal form and duration) Quiet period (no radio noise burst) Reconstruction quality of arrival direction? Zenith angle limitation (ϴ < 60°) Comparison plane/spherical reconstruction ? Expected delays : Expected wave detection time (on each antenna) with the reconstructed arrival direction

22. NOISE REJECTION PROCEDURE Signal form (signal form and duration) Quiet period (no radio noise burst) Zenith angle limitation (ϴ < 60°) Comparison plane/spherical reconstruction ? Expected delays : Expected wave detection time (on each antenna) with the reconstructed arrival direction Reconstruction quality of arrival direction?

23. NOISE REJECTION PROCEDURE Signal form (signal form and duration) Quiet period (no radio noise burst) Zenith angle limitation (ϴ < 60°) Comparison plane/spherical reconstruction Expected delays : Expected wave detection time (on each antenna) with the reconstructed arrival direction Reconstruction quality of arrival direction?

24. NOISE REJECTION PROCEDURE Signal form (signal form and duration) Quiet period (no radio noise burst) Amplitude decrease? (exponential form) Reconstruction quality of arrival direction?

25. NOISE REJECTION PROCEDURE Amplitude decrease? (exponential form) Lateral profile compatible with EAS signal exponential decrease!

26. NOISE REJECTION PROCEDURE Signal form (signal form and duration) Quiet period (no radio noise burst) Amplitude decrease? (exponential form) RADIODETECTED EAS CANDIDATES !! Reconstruction quality of arrival direction?

27. EAS CANDIDATES ? During 22 days of data taking, 10 5 events with direction reconstruction 17 EAS candidates ! Detection rate compatible with radiodetection energy threshold ( ~ 5.10 16 eV) Candidates sky distribution shows a clear North-South asymmetry (compatible with CODALEMA results) No definitive evidence for EAS radiodetection yet, but very promising results ! Extension with all available 21CMA antennas is needed (lateral profile) Time coincidence between antennas and particle detectors

28. EAS CANDIDATES ? No definitive evidence for EAS radiodetection yet, but very promising results ! Extension with all available 21CMA antennas is needed (lateral profile) Time coincidence between antennas and particle detectors ~50m Unconclusive criterion for small antenna array ! Only 6 antennas (max!) for a 4-paramater fit… Small array extension

29. SECOND PHASE (2010) : SET UP Antenna Scintillator Relocalization to the 21CMA crosspoint : Easy way to deploy a large array ! (without using long cables) 15 antennas since January 2010 3 scintillators (IHEP) since April 2010 + Tests of software Second Level Trigger in order to reduce the trigger rate in burst periods

30. SECOND PHASE (2010) : PRELIMINARY RESULTS Galactic sensitivity : High multiplicity events reconstruction: Radio sensitivity is still OK ! Moving source trajectory already identified Reconstruction is still OK !

31. SECOND PHASE (2010) : PRELIMINARY RESULTS Scintillator array: In 4 days of data taking : 30 events with 3 scintillators coincidence ! Already some coincidences between antennas and scintillators… but no EAS candidate in coincidence with 3 scintillators event yet! The second phase of CRs@21CMA is fully operationnal ! Just have to wait for a clear coincidence between EAS particles and radio emission …

32. SECOND PHASE (2010) : PRELIMINARY RESULTS Example of coincidence between : 2 antennas 2 scintillators Probability of fortuitous event: O.2% ! The setup works but we still have to wait …

33. NEXT STEPS Extension to 80 antennas (full array) At the crosspoint? On the east arm with optical fiber? Not decided yet…. Antenna modification Prototype of butterfly antenna (based on CODALEMA design) built by Xi’ian University presently in test at 21CMA : Less directionnal than log-periodic Better suited for very inclined shower detection Antenna response flat under 50 MHz Frequency bandwidth extension Limited by antennas (> 50 MHz), ADC (< 100 MHz) and optical transmission (50-200 MHz) With new antenna type and new optical transmission, a 20-100 MHz frequency bandwidth can be used!

34. NEUTRINO RADIODETECTION Neutrino characteristics : Point directly to its source Constraint on UHECR production mechanisms (hadronic acceleration process) Never done at the highest energies (>10 16 eV) !! x inter x decay « Neutrino » EAS creation mechanism : Decay ν τ -> τ in mountains τ decay in atmosphere Very inclined shower creation ! 21CMA site is a perfect place to study neutrino radiodetection !

35. DETECTION RATE ESTIMATION Neutrino EAS creation rate: How many neutrino related EAS are we going to detect ? Interaction neutrino – rocks Tau propagation in rocks Tau decay (Existing models with PYTHIA, GEANT4) Shower characteristics (number of particles, X max …)(CORSIKA) Had to be done for Ulastai geometry Neutrino EAS radiodetection ? : Horizontal shower never detected experimentally ! Shower in a constant density atmosphere never detected experimentally ! We need powerful radio simulation tools and/or experimental data !

36. Thank you!

37. NOISE REJECTION PROCEDURE Signal shape ? (signal waveform and duration)