High Energy Neutrino Flux studied in the ANTARES Deep-Sea Telescope

H. Löhner, High Energy Neutrino Flux 1 / 17

High Energy Neutrino Flux studied in the

ANTARES Deep-Sea Telescope

Herbert Löhner, KVI, University Groningen, The Netherlandson behalf of theANTARES collaboration http://antares.in2p3.fr

• research goals: deep cosmos• the detector setup: deep sea• status and performance• point-source flux• diffuse flux• future aims• summary


intriguing science questions:• origin of cosmic rays 1020 eV ?• astrophysical acceleration mechanism?• origin of relativistic jets?• dark matter?

cosmic sources of neutrinos• Active Galactic Nuclei: super-massive black hole

in center of galaxies• micro quasars: X-ray binaries (in our galaxy)• supernova remnants and shock acceleration

neutrinos reach Earth undisturbed: need sensitivity and angular resolution

HESS

TeV rays (p+X 0 ) in centre of our galaxy from supernova remnant RX J1713.7-39.

Expect: p+X

p

n

neutrino astronomy


detection principle

νμ

µγc

θc = 43º

-ν

ν

N X

Wneutrinos can interact through charged current interactionin the vicinity of a neutrino telescope

up-going neutrinos passing through the Earth are free from atmospheric muon background

track reconstructed from Cherenkov cone passing 3D grid of PMTs

p

103 atm.

p,

107

atm. per year

cosm.


the telescope setup

14.5 m

~60-75 m

buoy

350 m

100 m

Junctionbox

readout cables at -2475 m

storey

3 10” PMT/storey25 storeys/line12 detection lines:~900 PMT +acoustic detection

completed May 2008

45 kmelectro-opticalcableto shore


up-going muon: neutrino candidatereconstruction of muon trajectory from time, charge and position of PMT hitsassuming relativistic muons emitting Cherenkov light: 34.8O up-going muon

time (ns)

he

igh

t (m

)


expected performance: 12 lines

angular resolution

< 0.2° above 105 GeV

limited tracking accuracy due to time resolution:

Light scattering ~ 1.0 ns TTS in PMT ~ 1.3 ns time calibration < 0.5 ns OM position < 10 cm

(↔ < 0.5 ns)

dominated by reconstruction

rec− gener.

rec−gener.dominated

by kinematics

angular resolution = difference betweenreconstructed and MC generated angles vs. neutrino energy

6.0)TeV(

º7.0

E


neutrino candidatesfrom track zenith distribution

5-line data (May-Dec. 2007)+ 9-12 line data (2008)

341 days detector live time,reconstruction BBfit v3r2,single- and multi-line fit:

1062 neutrino candidates:

3.1 candidates/day

elevation angle

down-goingup-going

good agreement with Monte Carlo: atmospheric neutrinos: 916 (30% syst. error) atmospheric muons: 40 (50% syst. error)

1062 cand.


neutrino yield per day

for some periods: high level of bioluminescence decreases reconstruction efficiency


performance: data rate

Median rate of measured single photon counts: typ. 60 – 80 kHzcaused by bioluminescence (~ 30 kHz) and 40K decay (~ 40 kHz) with occasional bursts of extreme high rates (~ MHz)caused by macro-organisms (depends on sea current):multidisciplinary research,oceanographic studies


search for point-like sources

Well reconstructed

Badly reconstructed

uncertainties inangle reconstruction: median: 0.50.1O

12-line data: 0.40.1O

absolute orientation: 0.1O

data set:2007-2008 datataken with 5, 9, 10, and 12 operating detector lines


coordinates of 2190 neutrino candidates

Equatorial coordinates

no significant clusters of neutrino candidates

24 source candidates

most signal-like cluster: occurs in p = 88% of

background-only experiments


best limits for the Southern sky


search for diffuse sources

( Physics Letters B 696 (2011) 16

no excess of high-energy events above expected flux from atmospheric

background from atmospheric : ~ E-3.5

cosmicneutrino models: ~ E-2

search for high-energy diffuse-flux tail

energy estimate R based on extra light fromdelayed OM hits due tohigh-energy EM showers


limits on diffuse neutrino flux

competitive new diffuse-flux limit,some models predicting cosmic neutrino flux can be excluded


Multi-Messenger astronomyStrategy: higher discovery potential by observing different probes

higher significance by coincidence detectionhigher efficiency by relaxed cuts

GCNGRB Coord. Network:γ satellites

Alerts

Ligo/VirgoGravitational waves:trigger + dedicatedanalysis chain

TAROToptical follow up:10 srepositioning

MoUs for joint research


future plans: KM3NeT concept

array of multi-PMToptical modules (OM)sensing Cherenkov light

instrumented volumeseveral km3

sensitive to all flavours

E > 0.1 GeV

angular resolution min 0.1o for E > 10 TeV

acceptance: up-going tracks,up to 10o above horizon


Summary

• ANTARES completed since May 2008• angular resolution < 0.2 degree for energies > 100 TeV• neutrino candidate events selected (3 - 5 events / day)• point sources: best limit for the Southern sky• competitive new diffuse-flux limit• multi-messenger observations on alert• KM3NeT development for several km3 observatory

High Energy Neutrino Flux studied in the ANTARES Deep-Sea Telescope

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