1. 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

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

3. 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
antennas deployed on « hotspots » (sites with favorable topography)
See Ke Fang’s
GRAND talk

4. 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!

5. 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

6. 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

7. 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

8. 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

9. Short waves
GRANDproto35 DAQ
DAQ system (LPNHE design & proto, French company prod)
Trigger on MHz 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

10. 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

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

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

13. >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> eV
3-fold coincidences are shown in red, larger multiplicities in green

14. Provided funding on time!
Timeline
LONG road requiring several validation steps:
GRANDproto35 ( ):
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!

15. 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

16. 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!

17. Backup

18. 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.

19. DIRECTION RECONSTRUCTION
RADIO PERFORMANCES:
DIRECTION RECONSTRUCTION
Plane track reconstruction :
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

20. 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