The GRANDproto35 experiment Related talks: GRAND (Ke Fang ) TREND (Sandra Le Coz) The GRANDproto35 experiment A preparatory phase for the Giant Radio Array for Neutrino Detection Quanbu GOU on behalf of the GRAND collaboration ICRC2017, July 14, 2017

Earth-skimming neutrino detection nt Goal: search for cosmic neutrinos Detection principle: n-induced tau decays in atmosphere generate ~horizontal extensive air showers. [Fargion astro-ph/99066450, Bertou astro-ph/0104452] Issues: VERY seldom events Earth-skimming trajectories (m.f.p.(n) <~1000km) See Ke Fang’s GRAND talk

Size of the neutrino detector is a key parameter. >10000 km²? The GRAND project Size of the neutrino detector is a key parameter. >10000 km²? - technical capacity? - topology? Ulastai 200000 antennas deployed on « hotspots » (sites with favorable topography) See Ke Fang’s GRAND talk

GRAND challenges Main issues for GRAND: GRAND neutrino detection is based on autonomous radiodetection of ~horizontal air showers. This requires: Proper background rejection / event identification (online or offline) Proper geometry reconstruction (mostly crictical for CR physics) Solving technological challenges for a 200kAntennas array: trigger, data collection, maintenance, … GRANDproto35 target!

EAS radio detection with the GRANDproto35 Context: autonomous radio-detection of EAS so far with limited efficiency: ~10% for TREND (See S. Le Coz talk). Identified causes: Large background rates kill DAQ live time Air shower selection cuts strongly affect detection efficiency (~40% survival for TREND) GRANDproto35: dedicated set-up for air shower autonomous radiodetection with high-efficiency + high-purity

q = 65°, f = 8° The GRANDproto35 setup Antennas Scintillators Using polarization measurements for background rejection Principle: Wave triggers 5+ antennas Reconstructed direction of origin & polarization (h,b) @ trig’d antennas location: h = atan(max|Vy|/max|Vx|) b = atan(max|Vplane|/max|Vz|) x (EW) y (NS) z P h b

GRANDproto35 radio array 3D antennas (SUBATECH design, Xi’An prod) Reconstruction of full polarization info Additionnal signature for EAS/background rejection E ┴ v E ┴ B E 3-polar bow-tie antennas

If experimental values matches computed ones within : EAS tag For all trig’d antennas, compute expected h and b from simulated voltage, assuming signal due to EAS. If experimental values matches computed ones within : EAS tag Off-line validation of EAS candidates with scintillator array (select high-energy sample)  Quantitative evaluation of EAS identification Sim Vx Gu Junhua Sim Vx + noise Sim Vy Expected h for E field Expected h for voltage Expected h for voltage + noise Sim Vy + noise Simulated shower 1017 eV, [65°,8°] Sim Vz Sim Vz + noise

Short waves GRANDproto35 DAQ DAQ system (LPNHE design & proto, French company prod) Trigger on 30-100MHz analog signal Front end digitization GPS timing Enveloppe detection 100% duty cycle up to ~20kHz Simulated signal at filter output Simulated signal at ADC output (50MS/s) Simulated signal at power detector output

GRANDproto35 DAQ Lab tests: >95% recording rate for trigger rates up to 20kHz. On site tests: 100% of events recorded for ~few hours data taking test baseline level exhibits clear daily fluctuation as expected from Galactic Plane transit in antenna field of view: system is sensitive & stable. Onsite DAQ test: Trigger rate == record rate 0 events lost out of ~120k X arm Y arm Z arm 1.8µs waveform 3.6µs waveform Lab test

AERA DAQ @ GRANDproto35 3 units deployed summer 2016 Confirms excellent electromagnetic environment at GRANDproto35 site. Clustering of polarisation measurement is promising. AUGER-AERA DAQ

Scintillator array 21+3 air light-guide scintillator (tilted orientation) 6 already deployed for tests

>95% efficiency for E>2 1017 eV Scintillator array Zenith (top) and azimuth (bottom) distributions of events reconstructed with the 6-scintillators prototype array . Expected efficiency of the scintillator array for cosmic ray showers with an incoming direction within ±20 ° from North, zenith angle 70 ° > q > 40◦. >95% efficiency for E>2 1017 eV 3-fold coincidences are shown in red, larger multiplicities in green

Provided funding on time! Timeline LONG road requiring several validation steps: GRANDproto35 (2018-2020): Validate efficient automous radio detection R&D: autonomous stations with optimized sensitivity to inclined showers. Physics: precise polarization info of EAS radio emission GRANDproto300 (starting ~2020): 300 antennas. Validate very inclined CR shower detection R&D: GRAND trigger & data transfer. First GRAND hotspot (target: 2025): Full scale deployment (~10000km²) on one hotspot Validate setup design Physics: neutrino discovery instrument. Full setup (200’000km²) (203x): Could very well be splitted on different sites in the world. Detection unit target price: <500$/unit  ~100M$ project budget range Provided funding on time!

GRAND people Strong institutions from China (NAOC, IHEP) 35 physicists working on a GRAND white paper (release early 2018). You are welcome to join! GRAND white paper workshop, IAP May 2017

Conclusion Thanks for your attention! GRANDproto6 (6 antennas + 6 scintillators ) deployed for hardware tests  OK GRANDproto35: a dedicated set-up for air shower autonomous radiodetection with high- efficiency + high-purity Developments and tests of the detector parts are completed, and deployment is beginning. The full GRANDproto35 array is expected to start taking data early 2018. Thanks for your attention!

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Environment cuts Bckgd events strongly correlated in time & space Consecutive coincs: reject EAS candidate if 1+ coinc with 4+ antennas in common within 30s. Same direction events: reject EAS candidate if 1+ coinc with 2+ antennas in common and |Dj|<10° within 10 minutes.

DIRECTION RECONSTRUCTION RADIO PERFORMANCES: DIRECTION RECONSTRUCTION Plane track reconstruction : - 3037 events in 4 minutes Θ > 60° Max multiplicity: 40 Point source recons mult ≥ 22 antennas σ = 0.7° Total angular resolution <1.5° on the track (and improves with smaller zenithal angle) Estimated antenna trigger timing error: ±10ns

Discriminating parameters Spherical wave recons: point source reconstruction of backgrd sources close to array, EAS more distant. Signal shape: prompt signal for EAS Data: 45% killed Simu: 100% pass R>3000m Data: 66% killed R>3000m Simulated EAS: 92% pass