Milky Way over 21CM array (Gu Junhua)

The Tianshan Radio Experiment for Neutrino Detection

Olivier Martineau-HuynhNAOC G&C lunch talk May 28, 2014

Physics with UHE cosmic neutrinos• UHE neutrinos as a tool to study violent

phenomena in the Universe– One example: young extragalactic pulsars (Ke Fang et al., arXiv:1311.2044)

• UHE heavy nuclei emmited (= UHECRs)• Interaction with supernova ejecta• p+ l + nl (= UHE neutrinos)

Physics with UHE cosmic neutrinos

• GZK neutrinos

Ahlers et al., arxiv:1208.4181

GZK suppression?

p+gCMB D+ p+ + n. p+ l + nl.Great tool to study UHECRs.

Physics with UHE cosmic neutrinos• Lots of physics with

neutrinos above 1016eV– Test of pulsars, AGN, GRBs, – Test of UHECRs propagation– Probe distant Universe– …

• Downside: neutrino detection challenge + low flux @ UHE…

Need for cheap / scalable /easily maintainable detector.

Neutrino detection• Elusive particle requires dense & large target:– Ice: detection of shower initiated by n NC interaction– Ground

1000m

1400mICECUBE

ARIANA project

Birth of neutrino astronomy• IceCube 2012&2013

– Milestone in astronomy&astrophysics but:– Angular reconstruction for shower events ?– ~1 event/year above 250TeV.

ntt

• Earth + mountains as target for neutrino interaction (AUGER-type)• Radio detection of subsequent EAS (good at large zenith angles)

Extensive air shower

Radio detectionEth ~1017 eV

Neutrino detectionTarget = Earth

EAS radiodetection: principle

Bgeo

+-

F = qvBgeo

• Acceleration of relativistic charged particles in the Earth magnetic field (Kahn & Lerche, 1965): geosynchrotron emission

Bgeo

• Coherent effect detectable radio emission (~100ns & 10s µV/m)

Giant Radio Array for Neutrino Detection

• 100’000 antennas over 60’000km² would make the best UHE neutrino observatory.

(sensitivity evaluation TBC by full MC)• Major challenge: n identification

over background

Esh=1018eVq=90°472 antennas triggered

The GRAND project

Radio background

TREND antenna

TREND-50 antennas radio array:- 1.5km²- 220 days data subset- 1.2 1010 triggers recorded- 1.4 109 coincidences ~0.2Hz event rate over TREND-50 array (physical origin)

Expected EAS trigger rate:~100 events/day for E>1017 eV

Background rejection is a key issue for EAS radio-

detection.

Reconstrcuted source position

Background sources: HV lines, radio emiters, train, cars, planes, thunderstorms…

Autonomous EAS radio-detection with the TREND-50 setup

• 50 antennas deployed in summer-automn 2010, total surface ~1.5km².• Stable operation since January 2011.• Goal: establish possibility for autonomous radio detection of EAS.

TREND-50~1.5 km²

TREND-15(2010)

Background rejection

EAS signal Background

Shower axis

Radio cone

EAS signal- ~ Plane wavefront.- Fast drop of amplitude when

moving away from shower axis.- Random time and direction

Background: Close source:- Spherical wavefront- Fast drop of amplitude when moving away from source.Distant source:- ~ Plane wavefront- ~ Constant amplitude

Both: correlated in time & direction.

TREND-50 EAS candidates

EAS simulationProton showers @ 1017eV

(half sky)

West90°

30°

60°

90°

2011-2012 data(Antennas oriented EW):

396 candidates in 320 live days.

South90°

West90°

30°

60°

90°

South90°

TREND-50 EAS candidates

• Good match between data & EAS simulation:TREND-50 was able to identify EAS with limited background contamination.• Still a preliminary result:

• Simulation statistics to be increased.• Analysis cuts to be applied to simulated data.• If they remain, discepencies to be

understood (e.g. large q values)

Data (norm)Simu (norm)

Data (norm)Simu (norm)

n - induced shower radiodetection• Identification of standard EAS OK statistically (TREND-50).• Neutrino detection:

– Very bad Signal/Noise ratio: TREND-50 ID method not reliable enough.– Looking for horizontal showers: amplitude pattern at ground not as specific

as for standard ones

Standard EAS signal:focused ground patern & rapid drop of amplitude

n-induced (~horizontal) shower: no significant variation of amplitude along shower axis

(but OK in lateral direction)

Shower axis

Shower axis

Polarization measurment• EAS radio emission is polarized: at first order F = qv.Bgeo

Linear polarity, with P Bgeo & P shower direction

Shower core(q=66°, j = 354°)

Trigerred antennas

x

y

z

Ph

b

h ~7° on all antennas b ~89° on all antennas

GRAND-proto• Polarization measurment = powerfull identification tool for

EAS?• Test setup: «GRAND-proto»

– 35 3-polar antennas for a complete polar measurment (h = atan(Vy/Vx) & b = atan(Vz/Vplan).

– 6 antennas in test at present.– 21 scintillators for EAS offline validation (IHEP)– Full setup in summer 2015.

Conclusion

• Neutrinos are a powerfull tool for astrophysics (violent phenomena multi-messenger approach)

• Giant radio arrays could be the most adequate instrument for their detection.

• Main challenge: background rejection• TREND-50 results (very) encouraging, GRAND-

proto promising!