Hunting for Cosmic Neutrinos in the Deep Sea — The ANTARES Neutrino-Telescope Alexander Kappes Physics Institute Univ. Erlangen-Nuremberg October 14, 2005

Hunting for Cosmic Neutrinos in the Deep Sea —The ANTARES Neutrino-Telescope

Alexander KappesPhysics InstituteUniv. Erlangen-Nuremberg

October 14, 2005LBL, Berkeley

Introduction The ANTARES Neutrino Telescope Results from MILOM and Line0 The Future: KM3NeT

October 14, 2005 LBL, Berkeley

2Alexander Kappes Univ. Erlangen-Nuremberg

Cosmic Radiation Discovered in 1912 by

Victor Hess during a balloon flight

At high energies predominantlyconsists of:protons and particles

satellites/balloons shower detectors

What are the sources

and

acceleration mechanisms?



Messengers from Deep Space

Gammas (R~150 Mpc @ E=10 TeV)produced in electron or hadron acceleration

Protons E>1019 eV (R~50 Mpc)

Protons E<1019 eV

NeutrinosCosmicAccelerator

Neutrino production: Reaction of accelerated protons with interstellar medium, 3K microwave background radiation or synchrotron radiation

p + p() → + X + e + e +

) observation of prove for hadron acceleration Neutrino oscillation results in e : : ≈ 1 : 1 : 1

e : : ≈ 1 : 2 : 0

N () ≈ N ()

Magnetic fields



Detection of Cosmic Neutrinos

A ! X

Earth used as shield against all other particles

Čerenkov light:

Čerenkov angle: 42o

wave lengths used: 350 – 500 nm

low cross section requires large detector volumes

key reaction: + N ! + X

Detector deployed in deep water / ice to reduce downgoing atmospheric muons

p



Physics with Neutrino Telescopes

GeV TeV EeVPeV E

Low energy limit: short tracks

) only few photo sensors give signal

in sea water:40K + bioluminescence give high background

can only be lowered with a denser instrumentation of the water/ice

High energy limit: flux decreases with

E-2 … E-3

Large volumes required

. . . and also: - GZK neutrinos- supernova detection- magnetic monopoles- . . .

Dark Matter (WIMPs):direction, energy

Cosmic point Sources:direction, (energy)

Diffuse neutrino flux:energy, (direction)



Current and Future Neutrino Telescopes

AMANDA AMANDA IceCubeIceCubeMedium: iceMedium: ice

Data since 1997 Data since 1997 under constructionunder construction

NESTORNESTORMedium: sea water;Medium: sea water;under constructionunder construction

ANTARESANTARESMedium: sea water;Medium: sea water;under constructionunder construction

BAIKALBAIKALMedium: fresh water;Medium: fresh water;

Data since 1991Data since 1991

R&D project for kmR&D project for km33 detector: NEMO (Mediterranean) detector: NEMO (Mediterranean) Future project (kmFuture project (km33): KM3NeT (Mediterranean)): KM3NeT (Mediterranean)



Why a telescope in the Mediterranean? Sky coverage complementary to AMANDA/IceCube Allows observation of the Galactic Centre

South Pole Mediterranean

Sources of VHE emissions (HESS 2005)

notnotvisiblevisible

Mkn 501Mkn 501

Mkn 421Mkn 421

CrabCrab

SS433SS433

Mkn 501Mkn 501

SS433SS433

CrabCrab

VELAVELA

GalacticGalacticCentreCentre

not visiblenot visible

RX J1713RX J1713Galactic CentreGalactic Centre



Neutrinos from H.E.S.S. Sources?

Example: SNR RX J1713.7(shell-type supernova remnant)

W. Hofmann, ICRC 2005

Acceleration beyond 100 TeV.

Power law energy spectrum, index ~2.1–2.2.

Multi-wavelength spectrum points to hadron acceleration

) neutrino flux ~ flux Detectable in current and/or

future neutrino telescopes?!



The ANTARES Collaboration

20 Institutes from20 Institutes from6 European countries 6 European countries



The ANTARES Detector46

0 m

70 m

14.5

m

Str

ing

OpticalModule

JunctionBox

Buoy

Submersible

Cab

le to

Sho

re s

tatio

n

artist´s view(not to scale)

Hostile environment: pressure up to 240 bar sea water (corrosion)



One of 12 ANTARES Strings

Buoy keeps string vertical

(horizontal displacement < 20 m)

Storey 3 optical modules (45o downwards) electronics in titanium cylinder

EMC cable copper wires + glass fibres mechanical connection between storeys

Anchor connector for cable to junction box control electronics for string dead weight acoustic release mechanism



An ANTARES Optical ModuleGlass spheres: material: borosilicate glass (free of 40K) diameter: 43 cm; 1.5 cm thick qualified for pressures up to 650 bar

BB-screening-screening

optical moduleoptical module

Photomultipliers (PMT): Ø 10 inch (Hamamatsu) transfer time spread (TTS) = 1.3 ns quantum efficiency:

> 20% @ 1760 V (360 < < 460 nm)



Calibration systems

Time calibration with pulsed light sources required precision: 0.5 ns (1ns = 20 cm) 1 LED in each optical module Optical emitter

- LED beacon at 4 different storeys- Laser at anchor

Acoustic positioning system required precision: < 10 cm receiver (Hydrophone) at 5 storeys 1 transceiver at anchor autonomous transceiver on sea bottom

Tiltmeter and compass at each storey



DAQ and Online Trigger Data acquisition:

signals digitized in situ(either wave-form or integrated charge (SPE))

all data above low threshold (~0.3 SPE)sent to shore

no hardware trigger

Online trigger: computer farm at shore station (up to 100 PCs) data rate from detector ~1GB/s

(dominated by background) trigger criteria: hit amplitudes,

local coincidences, causality of hits trigger output ~1MB/s = 30 TB/year

Computer CentreComputer Centre

Control room



Online Trigger Each PMT sends frame with hits of last 13 ms to shore all 1800 concurrent frames (2 per PMT) are combined to 1 timeslice

which is analysed by the online trigger on one PC:

Trigger logic: Level 1: coincidences at one storey (t < 20 ns)

or large individual signal (& 2.4 SPE)

Level 2: causality condition t < n / c · x

Level 3: accept if sufficiently many causally related hits exist

cos C = 1 / n

Choice of trigger parameters:discard background events to match allowed trigger output rate (~1 MB/s)



Online TriggerImportant performance criteria: CPU time per event Scaling of trigger rate with increasing background rate Efficiency for E < 1 TeV ) Dark Matter (WIMP) search Increased sensitivity for certain directions (directional trigger)

) WIMP & point sources

EfficiencyEfficiencyBckg rate

First studies: Efficiency 100 GeV < E < 1 TeV increases by factor ~2 using directional trigger

but a lot of CPU power required

) further investigations necessary



Optimising the Online Trigger causality relation: t < n / c · x xmin = minimum of distances of all hit pairs in an accepted

eventMuons E > 10 GeVMuons E > 10 GeV Background (100 kHz)Background (100 kHz)

Cut @ xmin < 60 m: Background suppression ≈ 97%, Efficiency loss ≈ 1.5%



Signatures of Neutrino Reactions

Two basic light sources: Čerenkov photons from muon

track-like source Čerenkov photons from shower

hadronic or electromagnetic “point-like” source

visible in detector in all combinations

electromagn.shower

hadronicshower

muon track

hadronicshower

hadronicshower



Position reconstruction: use timing and position information

(xi ,yi ,zi ,ti) of N hits

distance di between assumed shower position (x,y,z,t) and OMi:

subtract di in pairs ) N-1 linear equations

solve system of linear equations algebraically ) # hits ¸ 5 (on at least 3 lines)

Shower Reconstruction with ANTARES(PhD thesis B. Hartmann)

Results (no cuts): Position resolution: ~1 m shift due to elongation of shower

(Preliminary)position resolution



Shower Reconstruction with ANTARES

Direction and energy reconstruction: prefit for direction and energy final parameters (, , E) ) Log-Likelihood fit

Ni = # photons in PMT i

# photons

parameterisationof c distribution

PMT opening angle

absorption

PMT angularefficiency

Results (no cuts): Event sample: Instrumented volume

+ 1 absorption length Angular resolution: < 13o (E > 10 TeV) but large tails in distributions Energy resolution: log(E) ¼ 0.1

(E > 100 TeV; 60 kHz bckgr per PMT,)

(Preliminary)

60 kHz bckgr per PMT

(Preliminary)



Shower Reconstruction with ANTARESNew idea for minimization strategy:(Diploma thesis R. Auer)

common to all events: each minimum lies in broad valley

impose grid on parameter plane (, , E) and calculate likelihood for centre of tiles

take l tiles with best likelihood values and divide those into sub-tiles) compare L of sub-tiles within one tile

stop after k iterations ( k ¼ 7) and take tile with best likelihood

Likelihood in - plane

60 kHz bckgr per PMT

(Preliminary)

Results (no cuts): Event sample: fully contained

events;30 TeV < E < 50 TeV

L function: similar to previous one angular resolution: ~2.4o

no tails in distribution



Recent Test-Lines: MILOM and Line0

Deployed March 2005, connected April 2005

MILOM: Mini Instrumentation Line with Optical Modules

Line0: full line without electronics(test of mechanical structure)



MILOM setupOptical components: equipped with final electronics 3+1 optical modules at two storeys timing calibration system:

two LED beacons at two storeys Laser Beacon attached to anchor

acoustic positioning system: receiver at 1 storey transceiver (transmitter + receiver)

at anchor

allows to test all aspects of optical line

Instrumentation components: current profiler (ADCP) sound velocimeter water properties (CSTAR, CT)



First results from MILOM (selection)

Single photon resolution (threshold 4 mV ¼ 0.1 SPE)

PMT charge spectrumpulse shape

single photon peak

Time (ADC channel)0 40 80 120

time (a.u.)

amp

litu

de

(a.u

.)



First results from MILOM (selection)Time calibration with LED beacons: Determination of the relative time offset of 3 optical modules

at same storey Usage of large light pulses ) TTS of PMTs small

Time difference between optical modules

Contribution of electronics to time resolution ca. 0.5 ns

t OM1 – OM0 t OM2 – OM0

=0.75ns =0.68ns



First results from MILOM (selection)Acoustic positioning: Several acoustic transponders installed Currently only results from 1D measurements available

Systematic effects under control on the level of 2 mm.

Time (day)2 4 6 8 10 12 14 16 18 20

96.58

96.59

96.60

96.61

Dis

tan

ce (

m)

distance from transponder (anchor) to receiver (first storey) vs. time

distribution around daily average

8 6 4 2 0 2 4 6 8Distance (mm)



First results from MILOM (Selection)

Environmental data:

Water temperature

+ sound velocity

Temperature almost constant at 13.2oC

Water temperature determines sound velocity (at given depth)

Water temperature

Sound velocity

Vel

oci

ty (

m/s

)



First results from MILOM

MILOM is a success:

Data readout (waveforms + SPE) is working as expectedand yields ns timing precision

In situ timing calibration reaches required precision for target angular resolution (< 0.3o für E & 10 TeV)

All environmental sensors are working well

Continuous data from Slow Control (monitoring of various detector components)

Lots of environmental and PMT data are available andare currently analysed



Line0 deployed to test mechanical structure equipped with autonomous recording devices

water-leakage sensors sensors to measure attenuation in

electrical and optical fibres recovered in May 2005

Results: no water leaks optical transmission losses at entry/exit of cables into/out of

electronics containers Effect caused by static water pressure;

Reason understood and reproduced in pressure tests Solutions available; detector installation not significantly delayed



ANTARES: further schedule

Assembly of first complete string (Line 1) started last week

Deployment and connection ca. January 2006

Completion of the full detector until 2007

From 2006 on: physics data!



The future: km3 detectors in the Mediterranean

HENAP Report to PaNAGIC, July 2002:

“The observation of cosmic neutrinos above 100 GeV is of great scientific importance. ...“

“... a km3-scale detector in the Northern hemisphere should be built to complement the IceCube detector being constructed at the South Pole.”

“The detector should be of km3-scale, the construction of which is considered technically feasible.”



Towards a km3 scale detector

scale up

new designthin out

Existing telescopes “times 50“:• to expensive• to complicated:

production/installation takes forever,maintenance impossible

• not scalable (band width, power supply, ...)

R&D required:• cost effective solutions: reduction

price/volume by factor & 2• Stability

Aim: maintenance free detector• fast installation

time for assembly & deployment shorter than lifetime of detector

• improved components

Large volume with same number of PMTs:• PMT distance:

given by absorption length in water (~60 m) and PMT characteristics) efficiency losses for larger distances



The future: KM3NeT

Start of the initiative Sept. 2002; intensive discussions andcoordination meetings since beginning of 2003

VLVnT Workshop, Amsterdam, Oct. 2003! second workshop 8.-11. Nov. 2005 in Catania

ApPEC review, Nov 2003. Proposal submission to EU 4. March 2004 EU offer about 9 M€, July 2005 (total budget ~20 M€); Start of the Design Study beginning of 2006;

Goal: Technical Design Report after 36 months Start of construction shortly afterwards

EU FP6: Design-Studie for a “Deep-Sea Facility in the Mediterranean for

Neutrino Astronomy and Associated Sciences”



The future: KM3NeT

Germany: Univ. Erlangen, Univ. Kiel France: CEA/Saclay, CNRS/IN2P3 (CPP Marseille,

IreS Strasbourg, APC Paris), UHA Mulhouse, IFREMER Italy: CNR/ISMAR, INFN (Univ. Bari, Bologna, LNS Catania,

Genova, Naples, Pisa, Rom-1, LNS Catania, LNF Frascati), INGV, Tecnomare SpA

Greece: HCMR, Hellenic Open Univ., NCSR Democritos, NOA/Nestor, Univ. Athens

Netherlands: FOM (NIKHEF, Univ. Amsterdam, Univ. Utrecht, KVI Groningen)

Spain: IFIC/CSIC Valencia, Univ. Valencia, UP Valencia UK: Univ. Aberdeen, Univ. Leeds, Univ. Liverpool, Univ. Sheffield Cyprus: Univ. Cyprus

Particle/Astroparticle institutes (16) – Sea science/technology institutes (6) – Coordinator

Partners in the Design Study:(contains ANTARES, NEMO, NESTOR projects)



Detector studies at Erlangen (S. Kuch)

The future: KM3NeT

Example (NIKHEF):

Advantages:• higher quantum efficiency• better timing resolution• directional information• almost 4 sensitivity• less penetrators

First studies running since a few months

inhomogeneous km3 detector

102 103 104 105 106 107

neutrino energy

ef

fect

ive

area 102

102

10-4

10-2

10-6

1

homogeneouskm3 detector

with same # cylinders

factor ~3 better for E < 1 TeV

Example:



Conclusions ANTARES:

Compelling physics arguments for ANTARES Shower reconstruction very important;

algorithms with good performance available MILOM: data readout is working as expected;

in situ timing calibration sufficient to reach angular resolution < 0.3o for E > 10 TeV

Line0: mechanical structure water tight and pressure resistant;losses in optical fibres at interface ) solutions available

Installation of first complete string about Jan. 2006;Completion of the whole detector until 2007

Well prepared for physics date to come in 2006

KM3NeT: future km3-scale -telescope in the Mediterranean km3-scale telescope on the Northern Hemisphere complementary

to IceCube at the South Pole 3 year EU funded Design Study (~20 M€): expected start beginning 2006

Documents

Hunting for Cosmic Neutrinos in the Deep Sea — The ANTARES Neutrino-Telescope Alexander Kappes Physics Institute Univ. Erlangen-Nuremberg October 14, 2005