Transcript KM3NeT
neutrinos and the sea Els de Wolf NIKHEF Ilias Meeting, Prague, February 8th 2005 KM3NeT, what is it? Design study for a Deep Sea Facility in the Mediterranean for Neutrino Astronomy and Associated Sciences Objective: develop cost-effective design of a 1 km3 neutrino telescope (~ 200 M€) Participants from existing collaborations: + + +… 2 Participating countries 3 Outline Purpose of -telescopes -telescopes in the Mediterranean The KM3NeT project Active Galactic Nuclei – History – Why in Mediterranean Sea – Physics Motivation – Design Requirements Gamma-Ray Bursts – Design Considerations – Challenges 4 Purpose of Neutrino Telescopes Astrophysics (-astronomy): – – – – Identify point sources Composition of jets Origin of cosmic acceleration Diffuse fluxes (extra) galactic -sources Particle physics: – Dark Matter searches: Neutralinos – Monopoles – Origin of UHE-cosmic rays Neutralino search: → +… 5 Neutrino Telescopes Projects Mediterrennean Baikal Antares Dumand NEMO NESTOR Amanda Icecube km3 6 Detection Principle Neutrino reactions (key reaction is mN -> mX) Cross sections and mechanisms known from accelerators Extrapolation to high energy (> 100 TeV) uncertain 7 ANTARES • Flexible strings • 10” PMTs, looking downwards • 2500 m depth • 40 km offshore Toulon • 70 m between strings • 14.5 m between storeys • One junction box 8 ANTARES deep sea data Measurements from an ANTARES Prototype String Rate measurements: strong fluctuation of bioluminescence background observed Rate (kHz) 10min 10min time (s) Also measured: current velocity and direction, line heading and shape, temperature, humidity, ... Important input for preparation and optimisation of ANTARES operation 9 NESTOR • • • • • • • • Rigid tower structure (titanium) Dry mateable connectors 15” up- and downward looking PMTs 3800 m deep Near Pylos Tower 32 m diameter 30 m between floors 144 PMTs First floor (reduced size) deployed and operated in 2003 10 (1/N)dN/dcos(θ) NESTOR: atmospheric muon flux M.C. Prediction Data Points Zenith Angle (degrees) 11 ….and comparison with others Good agreement confirms precise understanding of detector response, calibration, simulation and efficiencies 12 NEMO project 3340 m deep 80 km off shore Catania 16 arms per tower 20 m arm length Arms 40 m apart 64 PMTs per tower Up- and down-looking PMTs Wet mateable connectors Hierarchy of junction boxes 13 NEMO objectives Extensive site exploration R&D for km3: architecture, mechanical structures, readout, electronics, … Test installation foreseen with all critical components Completion expected by 2006 14 History KM3NeT July 2002: HENAP report to PaNAGIC “... a km3-scale detector in the Northern hemisphere should be built to complement the IceCube detector being constructed at the South Pole.” October 2003: VLVT workshop in Amsterdam ANTARES, NEMO, NESTOR Also industrial presentations e.g. Hamamatsu, Photonis, ETL, Saclant, Nautilus, Seacon, Ocean Design, … http://www.vlvnt.nl March 2004: KM3NeT EU FP6 Design Study submitted 15 Why in the Mediterranean Sea? Sky view complementary to ICECUBE Deep sites (up to ~5000m) close to shore: – shielding against atmospheric muons – good infrastructure – easy to reach by boat – short cable to shore – repair of detector line feasible Long scattering length – good pointing accuracy Experience of NESTOR, ANTARES, NEMO 16 KM3NeT and IceCube Complementary sky views*: IceCube KM3NeT Mkn 421 Mkn 501 Mkn 501 SS433 Not seen CRAB CRAB SS433 GX339-4 VELA Not seen galactic centre Region of sky seen in galactic coordinates assuming 100% efficiency for 2 down (*) ANTARES location provides a sky coverage of 3.5 p sr and an instantaneous common view with AMANDA of 0.5 p sr, and about 1.5 p sr common view per day. The Galactic centre is visible 2/3 of the time. 17 Scientific motivation HESS supernova remnant RXJ1713.7-3946 18 KM3NeT Design Requirements Effective volume: 1 km3, expandable Angular resolution: close to intrinsic resolution (< 0.1° for muons with Em > 10 TeV) Maximal angular acceptance for all possible detectable neutrino signals including down-going neutrinos at VHE Lower energy threshold of a few 100 GeV for upward going neutrinos with the possibility to go lower for from known point sources Energy reconstruction within a factor of 2 for muon events For all neutrino flavors Field of view: close to 4 Source tracking → from satellites: Duty cycle close to 100% Operational lifetime ≥ 10 years Cost effectiveness ~ 200 M€ per km3 All parameters need optimisation 19 Associated Sciences KM3Net Infrastructure will cooperate with the European Sea Floor Observatory Network Long term and continuous monitoring of ocean environment around Europe: – – – – Environment and Security Geohazards Global change Biodiversity 20 Design Considerations Detector architecture Photo detection Calibration Mechanics Readout and Data Transfer Deployment and Sea operations Power distribution Cost (~ 200 M€) Highly interconnected 21 Detector Architecture Homogenous strings? Towers? D. Zaborov at VLVT 200 m 20 x 60 m = 1200 m 40 m 200 m 250 m m m m= x 40 16 50 = 1000 m640 x 20 20 x 60 m = 1200 m 20 m x 60 m =Top 1200 m Top view view 250 50 floors 20 m step 16 floors with 4 PMTs each 40 m floor step 25 towers, each consists of 7 strings homogeneous lattice 20 x 20 x 20 downward-looking PMTs are directed downwards 10 “ photomultiplier tubes 64 NEMO - towers 22 Detector Architecture Homogenous strings? D. Zaborov at VLVT 20 x 60 m = 1200 m 20 x 60 m = 1200 m 20 x 60 m = 1200 m homogeneous lattice 20 x 20 x 20 downward-looking 10 “ photomultiplier tubes 23 Detector Architecture Towers? D. Zaborov at VLVT Top view 250 m 50 x 20 m = 1000 m 250 m 50 floors 20 m step 25 towers, each consists of 7 strings PMTs are directed downwards 24 Detector Architecture D. Zaborov at VLVT Towers? 200 m 40 m 16 x 40 m = 640 m 200 m Top view 16 floors with 4 PMTs each 40 m floor step 64 NEMO - towers 25 Sea Operations Rigid towers or flexible strings? Connection in air (no ROVs) or wet mateable connectors? Deployment from platform or boat? 26 Photo Detection Glass pressure vessel < 17” Hamamatsu 15” used by NESTOR Requirements for photo detection: – – – – High QE Large photocathode areas Wide angular coverage Good single photon resolution – High dynamic range Example of a device discussed: Hamamatsu HY0010 HPD Excellent np.e. resolution 27 Photo Detection Options Large segmented photocathode area with arrays of small PMTs packed into pressure housings low cost! Determine the photon direction via, e.g. – Multi-anodic PMTs plus a matrix of Winston cones 28 Readout and Data Transfer The data rate from a KM3 detector will be high estimated at 2.5-10 Gb/s Questions to be addressed: – Optimal data transfer to shore (many fibres + few colours, few fibres + many colours, etc.) – How much processing to be done at the optical module – Analogue vs. digital OMs implies differing approaches to design of front end electronics – Data filtering will play an important role – Distribution of (raw?) data to data analysis centres One possible data distribution concept Application of current PP GRID technologies to some of these open questions? 29 KM3NeT Challenges Design: – Simplify off-shore electronics (‘all-data-to-shore’) – Separate detection and calibration functionalities? Production model: – – – – Start construction at end of design study (TDR) Multiple production and assembly lines or structures Pressure and shallow water tests at production sites Transport and deployment ‘as is’ Site selection: – France, Italy or Greece 30 KM3NeT Production Model? Estimated size of the production: – 10.000 optical modules – 400 detector units (“lines”) – 40 calibration units 15 / day 12 / month 1.5 / month Start of data taking: 2012 – Start design study: 2006 – Start of production: 2009 Production time of 3 years 5 – 6 production sites are needed 31 Site Selection Final choice will depend on – – – – – – – – Depth Accessibility Distance from shore Bioluminescence rate Sedimentation Sea current Access to high speed networks on shore …… ? – Socio-political/regional considerations 32 Summary Compelling scientific argument for complementing IceCube with a km3 scale detector in the Northern Hemisphere The Mediterranean projects NESTOR, ANTARES and NEMO provide knowledge and experience for deep sea telescopes The FP6 KM3NeT Design Study has been accepted Foreseen start of the DS early 2006 Objective of the DS: TDR end 2008 33