A. BELIAS, NESTOR Institute, Pylos, Greece TeVPA 2009, July 13-17, SLAC1 KM3NeT, a deep sea neutrino telescope in the Mediterranean Sea KM3NeT objectives

A. BELIAS, NESTOR Institute, Pylos, Greece

TeVPA 2009, July 13-17, SLAC 1

KM3NeT, a deep sea neutrino telescope in the Mediterranean Sea

KM3NeT objectives

The KM3NeT Design Study

Outlook

Anastasios Belias for the KM3NeT Consortium



A -telescope in the Mediterranean sea

Complementarity with Ice Cube coverage

We need Northern -telescope to cover the Galactic Plane



The KM3NeT Consortium

• Consists of 40 Institutes of 10 European States• Includes expertise from all three precursor projects,

ANTARES, NEMO, NESTOR• Objectives

– Build and operate an extensible km3-scale water Cherenkov neutrino telescope in the Mediterranean Sea

– Sustain a deep-sea research infrastructure for earth and marine sciences

• KM3NeT, a multidisciplinary research infrastructure– Synergetic with European Multidisciplinary Seafloor Observatory

(EMSO)



KM3NeT Objectives• Astroparticle physics with neutrinos

– “Point sources”: Galactic and extragalactic sources of high-energy neutrinos

– The diffuse neutrino flux– Neutrinos from Dark Matter annihilation

• Search for exotics– Magnetic monopoles– Nuclearites, strangelets, …

• Neutrino cross sections at high(est) energies• The unexpected

• Earth and marine sciences– Long-term, continuous measurements in deep-sea– Marine biology, oceanography, geology/geophysics, …



The KM3NeT Design Study• Supported by the European Union in FP6 with ~9M€,

tot. value ~20M€.• Timeline:

• Started on Feb. 1, 2006 and will end on Oct. 31, 2009• Conceptual Design Report published, April 2008• Technical Design Report by end of 2009

• Detector Target Specifications:• Effective volume ≥ 1km3 • 0.1o angular resolution for muons (E ≥ 10TeV)• Energy threshold few 100 GeV• Field of view close to 4π for high energies



Deep-sea -Telescope at work• Upward-going neutrinos

interact in rock or sea water.

• Emerging charged particles (in particular muons) produce Cherenkov light in water.

• Detection by array of photomultipliers.

• Focus of scientific interest: Neutrino astronomy in the energy range 1 to 100 TeV.



• A standard optical module, as used in ANTARES, NEMO, NESTOR

• Typically a single largediameter (10’’) PMT

in a 17’’ glass sphere

Optical Module: standard...



… or many small PMTs

• Use up to 31 small (3’’) PMTs in a standard 17’’ glass sphere– very high QE PMTs

• Advantages: – increased photocathode

area– significant improved TTS– directionality– improved 1-vs-2 photo-

electron separation better sensitivity to coincidences

• Prototype tests underway



Electronics & Data Readout Concepts• Front-end options studies• New improved front-end chip in the deep-sea

– New FPGA/CPU

• Minimize active electronics in deep-sea– Reflective optical

modulator – on-shore timestamp

• Both options use fibers, Wavelength Division Multiplexing and Point-to-point networks

• “ALL DATA TO SHORE”

Interlink cables

SubmarineTelecom cable



Shore station real-time processing

• ALL digitized PMT data are sent to shore

• Expected rate of ~ 100Gb/s cannot be stored

• Perform time - position correlations of photomultiplier hits

• Correlations in real-time for the whole telescope

• Data reduction factor: ~10000



Configuration studies• Various geometries and OM configurations have been

studied• None is optimal for all energies and directions• Local coincidence requirement poses important

constraints on OM pattern



Mechanical structures

- Flexible tower structure:

Tower deployed in compactified “package” and unfurls thereafter

- String structure:

Compactified string at deployment, unfolding on sea bed



Deployment & Sea Operations• Deployment with ships

or dedicated platforms.• Ships:

Buy, charter or use

ships of opportunity.• Platform:

Delta-Berenike, under construction in Greece• Deep-sea submersibles

– Remotely operated vehicles (ROVs)– Autonomous Undersea Vehicles (AUVs) under study

Delta-Berenike: triangularplatform, central well with crane,

water jet propulsion

All deployment options require ships or platforms with GPS and DP



Earth and Marine Sciences• Associated science

devices will be installed at variousdistances aroundneutrino telescope

• Issues addressed:– operation without

mutual interference– interfaces– stability of operation

and data sharing



The candidate sites• Important Criteria• Bioluminescence rate• Biofouling• Sedimentation• Sea Currents• Absorption length• Depth• Distance from Shore• Access to shore facilities• Long-term site

measurementsperformed and ongoing

• Site decision requiresscientific, technologicaland political input



NESTOR 4.5 D Site36O 31.336’ N / 21O 25.635’ E

Site characterisation: Example

Transmission lengthvs

wavelength



KM3NeT Roadmap • Design study Feb. 1, 2006 – Oct. 31, 2009

– Produced Conceptual Design Report– Will produce Technical Design Report (by end. 2009)

• “Preparatory Phase” EU funded ~5M€, tot. ~10M€ 3/2008 – 2/2011– Initiate political process towards convergence and legal

structure– Prepare operation organisation & user communities– System prototypes– Commitment of funding agencies

• Site selection around 2010 ?• Construction Phase 2011+

– Start on extendable km3–scale neutrino telescope



KM3NeT Technical Design Report will address key issues

• Maximize physics output for given budget:• Which architecture and structure to use?

– String vs Tower concept• How to get the data to shore?

– Electronics off-shore or on-shore• How to calibrate the detector?

– Separate calibration and detection units• Design of photo-detection units?

– Large vs several small PMTs• Deployment technology?

– Dry vs wet ROV/AUV vs hybrid



Outlook• Joint efforts of ANTARES, NEMO, NESTOR to build a

km3-scale neutrino telescope in the Mediterranean Sea

• The Technical Design Report will be ready by end 2009

• The Preparatory Phase started

• Towards construction to start in 2011+

• The km3-scale neutrino telescope in the Mediterranean Sea will complement IceCube in its field of view





Backup slides



Simulations of reference detector• Sensitivity studies with a common detector layout • Geometry:

– 15 x 15 vertical detection units on rectangular grid,horizontal distances 95 m

– each carries 37 OMs, vertical distances 15.5 m

– each OM with21 3’’ PMTs

This is NOT the final

KM3NeT design!

Effective areaof reference

detector



Point source sensitivity

• Based on muon detection

• Why factor ~3 more sensitive than IceCube?– larger photo-

cathode area– better direction

resolution• Study still needs

refinements



Diffuse fluxes

• Assuming E-2

neutrino energy spectrum

• Only muonsstudied

• Energy reconstruction not yet included

Documents

A. BELIAS, NESTOR Institute, Pylos, Greece TeVPA 2009, July 13-17, SLAC1 KM3NeT, a deep sea neutrino telescope in the Mediterranean Sea KM3NeT objectives