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

H. Löhner, High Energy Neutrino Flux 1 / 16

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 XW

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

up-going neutrinospassing through the Earth are free from atmospheric muonbackground

trackreconstructed 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)

heig

ht (m

)


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 candidatesEquatorial 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-energydiffuse-flux tail

energy estimate Rbased 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

http://antares.in2p3.fr


backup


sky view (galactic coordinates)

Mkn 501

Mkn 421

CRAB

SS433

Mkn 501

RX J1713.7-39

GX339-4SS433

CRAB

VELA

GalacticCentre

AMANDA / IceCube ANTARES (43o N)(South Pole) (La Seyne sur Mer)

1.5 sr common view per day

acceptance density

acceptance range


expected performance: 12 lines

angular resolution

< 0.2° above 105 GeVlimited tracking accuracydue 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)

dominatedby reconstruction

rec− gener.

rec−gener.dominatedby kinematics

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

6.0)TeV(º7.0

E


track quality selection

reconstruction algorithm:•linear prefit photon hit coordinates x,y,z,t•minimization with hit-charge weights•Maximum likelihood (L) fit using

MC pdf of time residuals

quality cut variable:

solutions compatible of #

11.0ln

comp

compdof

N

NN

L

remaining 10 atmospheric / day1 atmospheric / day


Event DisplayHits are plotted for each line: height (z) versus time (t) Characteristic pattern depending on zenith angle and

distance of closest approachSeveral reconstruction strategies available and explored:1D, 3D, 2 minimization, Max. Likelihood optimization

upward

downward


track reconstruction

Position resolution: ~10 cm

Time resolution: ~ 2 ns

Cherenkov effect

n ~ 1.35

Optical Module OMi

CgC0 θsin

kv1

θtank1

c

tti

arrival time at OMi(vg = group velocity of light in water)


muon energy estimator performanceevaluate amount of emitted light

minimum-ionizing muon

neural network method

above 10 TeV: resolution is ~ factor 2


sea background

dense-water formation (cold winter) and local sea current instabilities caused sinking of large amounts of bioluminescent material (crustacea, zooplankton….)In press in Ocean Science

bursts from macro-organisms: ~ few MHz, strongly affected by sea currents:

mechanically stimulated bioluminescence

interesting issues for ESONET – EMSO:European Multidisciplinary Sea Observatory

to be published in Deep Sea Research I.


Local coincidences from 40K decay

Cherenkov

Gaussian distributedlocal coincidence time

Peak offset

•Efficiency of Optical Modules (~8%)

•Accuracy of time calibration (~0.5 ns)

Peakintegral

average coincidencerate 16 2 Hz

40K40Ca -

t (ns)

time offset (ns)

coincidence rate (Hz)


2 km4km

4-08-2010 26

Muon Depth-Intensity relation

)(c|)cos(|)h,I(h)0,I( corro

)ΔΩ(T)(A)h,μ()h,N()h,I(

eff

ooo

w.e.m 2000ho

MUPAGE parameterization

Parameterization from E. V. Bugaev et al., PRD 58 (1998) 05401

good agreement with Monte Carloand various experiments

( Astroparticle Physics 34 (2010) 179


new multinew multi--PMT PMT Optical Module conceptOptical Module concept

with 31 3with 31 3”” PMTPMT

forfor

high 2high 2--photon purity photon purity (sea background) (sea background)

andanddirectional sensitivitydirectional sensitivity

optical module / string design

String Detection Unit

Detection units:flexible tower of 900 m height with 20 storeys (floors) at 40 m distance.Storey: 6m long bar equipped with 2 multi-PMT OMs.


candidate deployment sites

ANTARES, NEMO, NESTORdeployment sites

criteria:bioluminescence,40K background,salinity, currents,water transparency:transmission length(recent data) (46+3) m at depth 2500 - 3000 m at = 450 - 470 nm

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

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