The GRAND proto

A prototype array to evaluate the potential of EAS identification of the

radio technique.

GRAND neutrino sensitivity

GRAND could reach 5-10x better sensitivity than Antartica projects.Angular resolution better than 0.1°.

To be confirmed/optimized with full MC.

PRELIMINARYGRAND :90% CL limit assuming • 0 candidates in 3 years• threshold = 3 1016eV • F = F0E-2 spectrum

Tens of GZK n /year expected!

Non-cosmic background• GRAND bckgd event rate estimation:

TREND50:~6 105 events/day/km²(~2.8 108 valid coincs

in 317 DAQ days)

GRAND:<300 events/day/km²

(safe estimate)2 107 evts/year over full array

Target rejection factor: 108 - 109

Expected n event rate:0-100 events/year

Factor 5 10-4

L=30

TREND-50 event multiplicity

L=5TREND50 → GRAND: Size x40000Antenna density /25 (Trig density /2000):Large step size helps you kill background!

GRAND background rejection

• Trigger pattern

Esh=1018eVq=90°472 antennas triggered

… probably not enough(shortest tracks)

Esh=1018eVq=87°27 antennas triggered

EAS polarization• EAS radio emission associated to 2

major sources:– Geosynchrotron effect FL = q v.Bgeo

E field linearly polarized: • Bgeo

• direction of propagation

– Charge excess: radial polarization

• Polarization info can be predicted, provided other shower parameters (E, , q f, xcore) are known.

• Very unlikely that bckgrd event would exhibit similar polarization signature.

Polarization as a reliable signature for EAS (?)

AERA, arXiv:1402.3677v2

h = atan(|Vy|/|Vx|) b =atan(|Vplane|/|Vz|)

• Test setup: «GRAND-proto»: a hybrid setup to evaluate quantitativly bckgrd rejection potential of polarization information

• 32 3-polar antennas + 21 scintilator array • Deployed at the noisiest location of TREND array, aiming at

showers coming from North.• Principle:

– Wave triggers 5+ antennas– Reconstruct direction of origin & polarization @ trig’d

antennas location:

GRAND-proto q = 65°, f = 8°

x (EW)

y (NS)

z

Ph

b

TREND antenna

Reconstructed source position

GRAND proto site

Principle of EAS polarization measurment in GRAND-proto

– For all trig’d antennas, simulate expected polarization assuming signal due to air shower.

EW

NS

Vert

Expected h for E field Expected h for voltage

Simulated shower 1017 eV, (65°,8°)

Noise at antenna output → V≠0 in any case → Error for extreme values ( , h b = 0° or 90°)

Expected h for voltage + noise

Polarization computation precision

Principle of EAS polarization measurment in GRAND

• If experimental polar matches one from simulated shower: EAS tag• Off-line validation of EAS candidates with scintillator array

Quantitative evaluation of EAS identification based on wave polarization.

• How good do we have to be (a rough estimate): If we perform 15° precision on reconstructed & h b :

– Random polar may be tagged as valid for one antenna with p = 0.03– p=0.035 = 1.6 10-8 for 5 antennas (4.6 10-10 for 6 antennas)

• How GRANDproto can be instrumental for GRAND:– ~100Hz coincidence rate expected on GRANDproto– 109 events reached within 3 months live R=109 may be tested within one year.

GRAND-proto status• Fully funded, deployment May 2015-early 2016• Radio antenna status

– Radio array: 3D active antennas (CODALEMA/AERA type, D. Charier @ SUBATECH)– All LNAs delivered, 6 prototype antennas in test during January-March 2014.

1 event triggering all 3 channels

GRAND-proto status

• Radio DAQ -> Jacques David + Patrick Nayman• Scintillator array -> Feng Zhaoyang