1. The T IANSHAN R ADIO E XPERIMENT FOR N EUTRINO D ETECTION: an autonomous radio-array for air showers detection Olivier Martineau-Huynh IHEP, 17/02/2011 IHEP (Hu HongBo, Gou QuanBu, Zhang Jilong, Zhang Yi & Olivier Martineau-Huynh) IN2P3 (Ardouin, Carloganu, Charrier, Lautridou, Martineau-Huynh, Niess, Ravel) NAOC (Thomas Saugrin, Wu XiangPing, Zhao Meng)

2. Radio detection of EAS B geo  e+e+e+e+ e-e-e-e- F = qv  B geo Acceleration of relativistic charged particles in the Earth magnetic field (Kahn & Lerche, 1965): geosynchrotron emission Coherent effect detectable radio emission LOPES: H. Falcke et al., Nature 435 (2005) CODALEMA: D. Ardouin et al., NIM A 555 (2005) D. Ardouin et al., Astro. Phys. 31 (2009)

3. Radio detection of EAS Why radio? – Measurement of direction of origin, energy (?), nature of primary (??) – Easiness of deployment & cost! 15k€/unit 3 tons <1k€/unit (?) <10kg (?)

4. Radio detection of EAS Only 2 established setups – <30 antennas: low stat – Slave-triggered to standards EAS detectors Still a long way ahead!!! Self-triggering? Amplitude lateral profile? Energy measurment? Primary nature determination? Threshold?

5. The TREND site Ulastai, Tianshan mountains, XinJiang autonomous province (2650m asl) Beijing Urumqi Ulastai

6. The electromagnetic environement Very clean radio environement above 20MHz. AM emitters FM emitters TREND @ Ulastai CODALEMA @ Nançay

7. The 21cm array a radio-interferometer for the study of the Epoch of Reionization (Wu XiangPing, NAOC) East West North South DAQ 4 km 3 km 127 log periodical antennas x 80 pods along 2 baselines

8. TREND prototype (2009) N E S W 21CMA pods TREND antenna First tests on site in June 2008. 6-antennas prototype running in January 2009. N

9. TREND prototype setup pod DAQ room 200MSamples/s ADC+CPU+disk optical fiber 84dB 50-200MHz filter 21CMA acquisition optical fiber64dB 50-100MHz filter TREND acquisition

10. TREND prototype performances Reconstruction performances N - static source (a car inside the array) Δ SN ~1.6 m & Δ WE ~1.5 m 4-antennas events 5-antennas events 6-antennas events spherical wave analysis

11. TREND prototype performances Reconstruction performances : plane track 4-antennas  = 8° 5-antennas  = 5° 6-antennas  = 2°

12. TREND antenna sensitivity Major radio source: thermal emission from the Galactic plane. Visible in Ulastai sky between 15h & 23h LST. Galactic plane @ 408MHz CRs@21CMA TREND antennas clearly exhibit an increased noise level when the Galactic plane is in the sky Local sideral time Signal noise level

13. TREND EAS search Discrimination of EAS from RF background - short/symmetrical/isolated pulses - in general, longer & repetitive pulses - random time & direction of arrivals - in general, localized sources or tracks - ~plane wave front - exponential decrease for lateral amplitude profile - spherical wave front - 1/distance decrease for lateral amplitude profile Background signals CR signals

14. Time [mn] Azimuth [deg] TREND EAS search Noisy periods rejection Select quiet periods (<3evts/3mins) 69% of 6-antennas prototype data (403h)

15. TREND EAS search «Quiet» periods data: 2259 events in 403 hours Select events with  <65° only.

16. TREND EAS search 3 additionnal cuts 25 EAS candidates  excess towards North (20/25 events) CODALEMA B geo see Astropart Phys paper: arXiv:1007.4359

17. EAS shower reconstruction Shower core position & lateral distribution could be reconstructed for 18 candidates. Not totaly reliable as no satysfying amplitude calibration performed so far.

18. TREND 2 nd phase (2010) 15 antennas 3 scintillators : ground array for EAS detection cross-check

19. Scintillator array 50cmx50cmx2cm plastic scintillator + PMT PMT signal directly fed into optical transmiter (20- 200MHz) Independent trigger for all 15+3 detectors Scintillator threshold set for ∼ 25Hz individual trigger rate. time [ μ s]

20. Scintillator data 620 3-fold coincidences found in 19 days of scintillators’data. The 3-scintillators array is a valid EAS detector

21. Radio data Selection of ~15 EAS candidates within the 19 live days (applying selection procedure defined with the prototype)

22. Hybrid coincidences 3 events with 4+ antennas & 3 scintillators in coincidence 2 events with 4+ antennas & 2 scintillators in coincidence

23. Hybrid coincidences Random coincidences? Triggers on PMT signals? – Trigger delays not consistent with expected propagation times. – For 4 hybrid coincs (out of 5), some antennas triggered before the scintillators. Expected rate for 2 independent events given by: f A = 1.6 10 -4 Hz rate of 3-folds scintillator events f B < 10 Hz rate of radio events (multiplicity≥4) Δt = 2 µs f rdm = 2*f A *f B /(f A +f B )*(1-exp(-(f A +f B ) Δ t)) Hz f rdm = 0.1/year... No!

24. Hybrid coincidences Independent reconstruction for 3 hybrid coincs with 3 scints Radio recons Scint recons CoincA Θ= 52±1° φ =195±1° Θ= 49±3° φ =191±4° CoincB Θ= 61±3° φ =359±2° Θ= 67±5° φ =3±4° CoincC Θ= 42±1° φ =55°±4° Θ= 36±3° φ =56°±5° Coincidence A First autonomous radio-detection of EAS! (see Astropart Phys paper: arXiv:1007.4359)

25. TREND 3rd phase (2011) 50 antennas (1.1 km²): largest EAS radio- detection setup Numerous EAS candidates expected! Lots of analysis work and physics ahead.

26. Next steps Improve setup: – Faster ADC (500MHz) – Front end digitization – 2 nd level trigger – Upgrade optical transmetters & receivers – Move to 20-100MHz frequency range (?) Need for financial support & expertise!

27. Next steps A hybrid detector? – 24 scintillators (?) for full ground array – Energy calibration, shower reconstruction comparison, lateral profile studies… – Complementary (?) to CODALEMA & AERA – Financial support?

28. TREND long term perspective High energy neutrinos detection through tau production in rock and decay in atmosphere  

29. Neutrino detection at TREND High mountains: – Additional target for – Screen for CR showers Environment: few RFI sources+very little thunder activity Radio optimal for inclined showers detection (?) Ulastai TREND

30. Detection cross sections E = 10 16 eV Averaged over  E = 10 18 eV Averaged over  TREND site topology Flat site (close showers) TREND site topology Flat site (close showers) Upward going Downward going Upward going Downward going

31. Neutrinos flux limit TREND AUGER (PRD 2009) AUGER integrated AUGER integrated  Waxmann-Bahcall limit 90%CL limit assuming flux  =  0 /E 2 and no candidate within 4 years (& 0 background expected) Results obtained with optimistic hypothesis. To be confirmed with final antenna design + radio simulation

32. Antenna R&D Design for optimal sensitivity along horizon? – On-going work – On-site tests foreseen in 2011

33. Conclusion TREND project running since 2008. Autonomous radio detection of EAS established (arxiv:2010.4359). At present largest setup for EAS radiodetection. Attractive physics soon to come! System upgrading foreseen (electronics+ ground array?) Neutrino search late 2012? (new antenna design)

34. 谢谢 ! Thank you !