TREND program : establish possibility of automous radio-detection of EAS : 6 antennas to define DAQ and analysis algorithm 2010: 15 antennas + 3 scintillators, first EAS candidates : 50 antennas, large statistics.

EAS signal Background Ex: signal pattern: Data treatment: elm background point sources Distinct features compared to EAS radio signals. → Localized background can be rejected through data processing. Shower axis

TREND-50 results 2012: analysis of 320 live days with E-W polar. 323 EAS radio candidates selected. Arrival direction distribution follows what is expected from EAS events. (to be confirmed with MC simulation… in progress) Geosynchrotron intensity map (analytical treatment)… To be confirmed by simulation. In progress.

TREND-50 results 2013: antennas rotated to N-S polar. Analysis of 3 months of data: 11 candidates. So far so good. Full dataset (+6 months) needed for final confirmation. Confident that autonomous radio-detection of standard EAS is possible with limited background contamination.

TREND Setup for (almost) free thanks to 21CMA. - Limited ressources and expertise on the radio technics. -Focus on a single well defined objective: run radio array in standalone mode for EAS detcetion. -Goal achieved (to be confirmed & published), thanks to high trigger rate & dedicated candidate selection algorithm.

TREND program : establish possibility of automous radio-detection of EAS : 6 antennas to define DAQ and analysis algorithm 2010: 15 antennas + 3 scintillators, first EAS candidates : 50 antennas, large statistics :preparatory phase for a GIANT array dedicated to INCLINED showers.

GRAND sensitivity (threshold eV)  (threshold eV) GRAND could reach similar (up to 2x better) sensitivity compared to Antartica projects. Angular resolution better than 0.1°. To be confirmed/optimized with full MC. PRELIMINARY

TREND Optimise background rejection, in particular for inclined showers (linked to neutrinos). Tool: – Ground patern  – Polarisation (?): EAS signal linearly polarized & perpendicular to direction of origin and Bgeo (at 1st order). 1st results expected summer 2015!!! (CNRS request)

GRAND-proto Polarization measurement – Dual arm ‘Butterfly’ antennas developped for CODALEMA & AUGER – Upgrade to 3-arm antennas by TREND to retrieve full polar info (Xi’An XiDian University) – Will be tested on site next week. Butterfly AUGER 3-polar antenna prototype in Xi’An

GRAND prototype Prototype array of 30 antennas ( ) + 21 scintillators ( ) – Principle of EAS selection: For all events detected: Measure polarization on all triggering antennas Select events with polarization pattern compatible with EAS. Offline cross-check with scintillator data. – Allows a quantitative evaluation of the EAS selection procedure. – Array along 21CMA North-South baseline (fibers for signal transmission) – Offline cross-check reliable ONLY if  (ground array)=100% ! Requires precise simulations!

Electronic prototype test 2 antennas arms Early amplification Fiber to DAQ Lin HaiChuan Front-end trigger + digitization TREND 1GHz! Fast front-end digitization (1GHz+12bits) developped by IHEP (Liu ZhenAn trigger Lab) & tested succesfully on site early March. Technically very chalenging & too expensive!

Electronique GRAND-proto Alternative under study: power detector (integrating circuit) + slow numerisation (100MSPS)

Filter MHz ~15dB Power detector ADC 100MSPS Analog card Active antenna FPGA x3 Compa rateur Threshold x3 DAQ fibee GPS Timing Analog trigger

BACKUP

Trigger principle / Buffer analysis T0: On each machine uNANT (NANT in ): – For every new buffer, compute  noise over 1024 samples of 1 st sub-buffer. – If sample i with amplitude A i > N x  noise, trigger of level T0 on this antenna. 6<N<10. T1: If at least 4 antennas have T0 triggers within a causal time window (  t<  L/c), then data is sent to disk on machine u183 for all antennas with T0s – to data file R[NRUN]_A[NANT]_data.bin: 1024 samples centered on sample i – to time file R[NRUN]_A[NANT]_time.bin : UNIX second of sample i Buffer index of sample i Subbuffer index of sample i Position of sample i in subbuffer. 5  noise  x  noise Code in C with MPI for Master/Slaves dialogs. Master program in python. Securities to check computer & ADC card status, buffer status, machines dropping out of DAQ. Monitoring tools to check status.

TREND acquisition chain Filter MHz LNA 24dB 40dB Filter MHz Optical transmitter buffer 200MB disk antenna ~100m coax cable <4km fiber Optical recevier ADC 8b 200MS/s Electronic board Pod DAQ room

TREND acquisition chain fiber to the DAQ room (<4km)

64dB ampli MHz filter Optical receiver Antenna 101 U G disk Triggered events Data file u101 Time file u101 scans ADC 8bits 200 MS/s Circular buffer 200MB Circular buffer 200MB computer u101 CPU (trigger) 64dB ampli MHz filter Optical receiver Antenna 158 Triggered events Data file u158 Time file u158 scans ADC 8bits 200 MS/s Circular buffer 200MB Circular buffer 200MB computer u158 CPU (trigger) 50 parallel & identical chains Optical fiber 100m<d<4km 1 triggered event = 4 words in time file & 1024 samples in data file DAQ room computer u203 (ADCs init) start signal 50 parallel & identical chains

Background discrimination EAS radio signals features: -Focused signal spot on ground (decreasing when moving away from shower axis) -~ Flat wavefront -Short (<500ns) pulses -Isolated pulses -Random in time -Random in direction -Come from the sky -Polarized (  shower direction &  B geo ) -Frequency signature (?) Background radio signals features -If distant: ~constant amplitude -If close: curved wavefront -Usualy long pulses -Usually repetition -Possible pattern for consecutive triggers (50Hz) -Point sources or trajectories -Mostly from ground -Non polarized -Frequency signature possible… EAS and background have distinct features → data processing written to efficiently select candidates & reject background

TREND candidate selection procedure 10 ms  power line Rejection of event bursts Rejection of events with neighbours  Rejection of waveforms with bad shape Rejection of radius of curvature<500m Rejection of events with A max /A min <1.5 Rejection of events with ‘holes’ in the trigger pattern. Info on direction of arrival hidden during selection process.

TREND-15 setup (2010) 15 log-periodic antennas + 3 particle detectors. 400 m 800 m Ardouin et al., Astropart. Phys 34, 2011 First EAS identification with autonomous radio array N ants θ radio θ scints ϕ radio ϕ scints 461±367±5359±23±4 452±149±3195±2191±4 542±136±355±456±5 445±149±312±110±5 756±253±4323±2331±5 Some radio EAS candidates are coincident with scintillator coincidences + direction recons match! Selection of radio EAS candidates with dedicated algorithm Radio data (subset) Reconstruction of 3-fold scintillator coincidences  EAS Scintillator data Independant trigger & analysis of scint data (EAS) & radio data (EAS radio candidates).

The TREND-50 setup 50 antennas deployed in summer-automn 2010, total surface ~1.5km². Stable operation since January Goal: acquire large(r) stat of EAS. Quantify background rejection. TREND-50 ~1.5 km² TREND-15 (2010)

Giant Radio Array for Neutrino Detection: how realistic is a 100kAntennas array ? Manageable if minimal amount of info delivered by antenna (16 bits per trigger, T0: 1kHz/antenna, T1: 200kB/s) Affordable if unit price < 500 €. P. Lautridou 2011