Upper Limit on the Diffuse $ν_μ$ Flux with the ANTARES Telescope

0.19 MB·English

by  Simone Biagi

NuclearPhysicsB
Proceedings
Supplement
NuclearPhysicsBProceedingsSupplement00(2011)1–1
Upper Limit on the Diffuse ν Flux with the ANTARES Telescope
µ
SimoneBiagifortheANTAREScollaboration
DipartimentodiFisicadell’Universita`andINFN,VialeBertiPichat6/2,40127Bologna,Italy
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n Abstract
a
J A search for very-high energy cosmic muon neutrinos from unresolved sources is presented using data collected
bytheANTARESneutrinotelescope. Datacorrespondingto334daysofequivalentlivetimeshowthattheobserved
5
1 numberofeventsiscompatiblewiththeexpectednumberofbackgroundevents. A90%c.l. upperlimitonthediffuse
ν fluxissetatE2Φ =5.3×10−8GeVcm−2s−1sr−1intheenergyrange20TeV–2.5PeV.
µ 90%
]
E Keywords: cosmicneutrinos,diffuseflux,underwaterneutrinotelescope
H
.
h
The ANTARES neutrino telescope is a three- the topology of the events, the latter is an irreducible
p
- dimensional array of 885 photomultiplier tubes (PMT) background. As the spectrum of cosmic neutrinos is
o
distributedover12linesinstalledintheMediterranean expected to be harder than that of atmospheric neutri-
r
t Sea [1]. A search for a diffuse flux of muon neutrinos nos,thesignalsearchedforcorrespondstoanexcessof
s
a usingdatacollectedfromDecember2007toDecember highenergyevents,producedbyastrophysicalsources,
[ 2009ispresented. inthemeasuredenergyspectrumwithoutanyparticular

1 Atmospheric muons and neutrinos are the main assumptiononthesourcedirection.
v sources of background in a neutrino telescope. The Atestsignalspectrum∝ Eν−2 andthe“conventional”
4 formercanbesuppressedbyapplyingrequirementson atmosphericBartolflux[2]weresimulated. Anenergy
7 estimator [3], based on the mean number of hit repeti-
9 tions (R) on the PMTs, is used to separate the diffuse
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fluxsignalfromtheatmosphericν background. Acut
. µ
1 overtheRvariableisoptimizedwiththeModelRejec-
0
tionProcedure[4]usingMonteCarloexpectationsonly.
1
Ninehighenergyneutrinocandidatesarefoundwith
1
: anexpectedbackgroundof10.7±2events.The90%c.l.
v upper limit on the diffuse ν flux including systematic
i µ
X uncertaintiesiscomputedwiththemethodof[5]: itis
r
a E2Φ =5.3×10−8GeVcm−2s−1sr−1 (1)
90%
intheenergyrange20TeV–2.5PeV.Theresultiscom-
paredwithotherexperimentsinFig. 1.
[1] G.Anton,theseproceedings.
[2] G.D.Barretal.,Phys.Rev.D70(2004)023006.
Figure1: TheANTARES90%c.l.upperlimitforaE−2diffuse [3] S.Biagi,PhDthesis(2010)http://antares.in2p3.fr/.
ν +ν flux,comparedwiththeresultsobtainedfromotherex- [4] G.C.HillandK.Rawlins,Astropart.Phys.19(2003)393.
µ µ
perimentsandtheoreticalpredictions. See[6]andreferences [5] J.Conradetal.,Phys.Rev.D67(2003)012002.
therein. [6] T.ChiarusiandM.Spurio,Eur.Phys.J.C65(2010)649.