Development of China-VO ZHAO Yongheng NAOC, Beijing Nov. 2003.
Milky Way over 21CM array (Gu Junhua) The Tianshan Radio Experiment for Neutrino Detection Olivier...
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Transcript of Milky Way over 21CM array (Gu Junhua) The Tianshan Radio Experiment for Neutrino Detection Olivier...
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.