Post on 18-Dec-2015
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.
nt
t
• 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 detection
Target = 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.