Status of the ANTARES Neutrino-Telescope

Status of the ANTARES Neutrino-Telescope

Alexander KappesPhysics InstituteUniversity Erlangen-Nurembergfor the ANTARES Collaboration

WIN´05, 6.–11. June 2005Delphi, Greece

Introduction The ANTARES Detector First Results from Test-Lines Outlook

6. - 11. June 2005 WIN´05 Delphi, Greece

2Alexander Kappes University Erlangen-Nuremberg

Active Galactic Nuclei

Supernova Remnant (RX J1713.7-3946)

Gamma Ray Burst

Cosmic accelerators

(Bepposax)

Hubble

H.E.S.S.



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: + A ! + X

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



Physics with Neutrino Telescopes

Searching for point-like neutrino sources

Measurement of diffuse neutrino flux

Search for Dark Matter (WIMPs)

Search for exotic particles:e.g. magnetic monopoles



Why a Neutrino Telescope in the Mediterranean Sea? Sky coverage complementary to telescopes at South Pole Allows to observe the region of the Galactic Centre

Not seenNot seenMkn 501Mkn 501

Mkn 421Mkn 421

CrabCrab

SS433SS433

Mkn 501Mkn 501

GX339-4GX339-4SS433SS433

CrabCrab

VELAVELA

GalacticGalacticCenterCenter

Not seenNot seen

South Pole Mediterranean Sea

Sources of VHE emission (HESS 2005)



The ANTARES Collaboration

20 institutions from 20 institutions from 6 European countries6 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



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)



DAQ and Online Trigger Data acquisition:

signals digitized in situ(either wave-form or single photo-electron (SPE))

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

no hardware trigger

Online trigger: computer farm at shore station (~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 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

EfficiencyEfficiency

cos C = 1 / n

Advanced algorithms under development



Calibration devices (Overview)

Time calibration system 1 LED in each optical module Optical beacons

- LED beacons at 4 different storeys- Laser beacon at anchor

Acoustic positioning receivers (hydrophones) at 5 storeys 1 transceiver at anchor autonomous transceivers on sea floor

Tiltmeter and compass at each storey



Time-Calibration Systems timing resolution of PMT signals determines pointing accuracy

limited by intrinsic TTS of PMTs (1.3 ns)) resolution of time calibration has to be better than 0.5 ns

expected variations of individual time offsets of PMT signals ~10 ns

complete calibration performed prior to deployment

two independent in situ calibration systems for PMTs available:

Flashed LEDs in optical modules: blue LED attached to back of each PMT illuminates only local PMT

Flashed optical beacons: illuminate mainly PMTs on neighbouring strings each beacon contains PMT for recording of emission time

OMPMT



Positioning System motion of lines due to sea current (up to 30 cm/s) 0.5 ns timing resolution requires 10 cm position accuracy for each PMT

Tiltmeters and compasses: resolutions: tiltmeters = 0.2o , compasses = 1o

Acoustic system: transmitter frequencies: 8–16 kHz (long distance)

40–60 kHz (short distance) distance measurements via run time of acoustic signals reconstruction of storey positions via triangulation

System designed to provide PMT position accuracy better than 10 cm.



Environmental Parameters

Continuously measured with various instruments on a dedicated string (Instrumentation Line) or at string anchors

quantities directly influencing reconstruction attenuation length (25–60 m, depending on wave length and time)

resolution ¼ 4 m sound velocity ) acoustic positioning system

resolution = 0.1 m/s

other quantities measured direction/speed of water current (via Doppler effect)

precision: v = 0.5 cm/s, = 0.5o

temperature, salinity (via conductivity) water pressure (device attached to anchor)



Angular resolution (simulation) E < 10 TeV: dominated by

kinematics (Æ[, E > 10 TeV: dominated by reconstruction accuracy

Muon Reconstruction

Energy resolution (simulation)

low E: muon track length E > 1 TeV: Čerenkov light from

radiative losses (small elm. showers)

< 0.3o (E > 10 TeV) (log E) ¼ 0.3 (E > 1 TeV)

Muon momentum



Detector Infrastructure and Prototype Lines

Deep-sea cable to shore station deployed

Junction box deployed and connected to deep-sea cable

Prototype lines deployed, connected to junction box and successfully recovered after 5 months



Results from Prototype Lines (2003)

Long term measurements of optical background in the deep sea:

0.4 seconds0.4 seconds 3.53.5 monthsmonths

Baseline rateBaseline rate

Technical problems: damaged optical fibre inside cable + water leak in electronics container

) no data with ns time resolution + loss of a storey



New 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 MILOMTiming calibration with LED beacons: Measured relative offset of 3 optical modules on same storey Large light pulses used ) TTS of PMT small

Optical beacon signal

Time (ns)

Am

plit

ud

e

Time difference between optical modules

electronics contribution to resolution around 0.5 ns investigations in progress to separate various contributions

t OM1 – OM0 t OM2 – OM0

=0.75ns =0.68ns

beacon signal



First results from MILOMAcoustic 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

Compass headings from all three MILOM storeys:

mostly synchronous movement of all storeys



First results from MILOM

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

)




Environmental data: Sea current (current profiler)

Most times sea current < 15 cm/s Significant changes of direction over periods from hours to days




MILOM is a big success:

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

In situ timing calibration and acoustic positioning reach expected resolution

All environmental sensors are working well

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

Lots of environmental and PMT data available; intensive studies ongoing



Line0 deployed to test mechanical structure equipped with autonomous recording devices

water leak sensors sensors connected to electrical and fibre loops

for attenuation measurements recovered in May 2005

Results: no water leaks occurred optical transmission losses at various points on fibres

evidently all losses occur inside electronics container at entry and exit from cylinder

presently under intense investigations

On first prototype strings fibres inside cables were

damaged



ANTARES: further schedule

First full string (Line1) to be deployed and connected end of 2005

Full detector installed in 2007

From 2006 on: physics analysis !



The future: KM3NeT

common effort of European telescope groups(ANTARES, NEMO, NESTOR) + associated sciences

aim: build and operate a km3 neutrino telescope in the Mediterranean Sea

complementary to IceCube at the South Pole

expect to get EU funding (10 MEuro) for a design study (total budget 24 MEuro) by beginning of 2006

Technical Design Report early 2009

km3 detectors required to exploit full physics potential of neutrino telescopes



Conclusions MILOM proved to be a big success

data readout is working as expected in situ timing and position resolution sufficient to reach

angular resolution < 0.3o for neutrinos with E > 10 TeV many more data to analyse

Line0 results mechanical structure water tight and pressure resistant optical losses in fibres currently under

intense investigation

First full string expected to be deployed this year;Full detector in 2007

Well prepared for physics data to come in 2006

Documents

Status of the ANTARES Neutrino-Telescope