Deep-sea neutrino telescopes Prof. dr. Maarten de Jong Nikhef / Leiden University

contents Neutrino astronomy Antares KM3NeT issues, ideas prototype next generation neutrino telescope issues, ideas

Neutrino astronomy n g p neutrinos Why neutrinos? no absorption no bending Scientific motivation: origin cosmic rays creation& composition relativistic jets mechanism cosmic particle acceleration composition dark matter neutrino telescope

Use sea water as target/detector 1960 Markov’s idea: Use sea water as target/detector range of muon detect Cherenkov light transparency of water

muon travels with speed of light (300,000 km/s) → ns (10 cm) @ km How? wavefront neutrino muon 1 2 3 4 5 ~100 m interaction ~few km muon travels with speed of light (300,000 km/s) → ns (10 cm) @ km

General layout light detection real-time event distribution 3-5 km shore station transmission of (all) data data filter

prototype neutrino telescope Antares prototype neutrino telescope ‒ 100 persons ‒ 25 M€ 1997‒2005 R&D site explorations measurements of water properties 2005‒2008 construction-operation 2008‒2017 operation

Antares 12 lines ~2.5 km 500 m 250 Atm. ~200x200 m2 25 storeys / line

Detection unit Optical beacon timing calibration 10” PMT photon detection Electronics readout Hydrophone acoustic positioning ~1 m titanium frame mechanical support

Dutch industry Gb/s transceiver passive cooling DC–DC converter

wet-matable connector (2) deep-sea network connector (3) penetrator (2) container CPU FPGA PMT e/o 100 Mb/s 5x15 m optical fiber (21) penetrator (3) container Ethernet switch 1 Gb/s e/o e/o 5‒25x15 m junction box container DWDM filter optical fiber (4) (40) 1 km 40 km wet-matable connector (2)

data flow time CPU CPU CPU CPU CPU CPU off-shore on shore Ethernet switch data filter data filter data filter

data flow time CPU CPU CPU CPU CPU CPU off-shore on shore Ethernet switch data filter data filter data filter

data flow time CPU CPU CPU CPU CPU CPU off-shore on shore Ethernet switch data filter data filter data filter

Antares deep-sea infrastructure 1 km3 one main electro-optical cable 900 PMTs, hydrophones, ADCP, seismometers, etc. 10 kW, 1 GB/s one main electro-optical cable 50 km, AC, 1 cupper conductor + sea return network active multiplexing locally (Ethernet standard) passive multiplexing based on DWDM technology low number of channels for reliability of offshore transceiver (l stability) operation 10 years (some maintenance’ data transmission signal recovery by amplification

definitive neutrino telescope KM3NeT definitive neutrino telescope ‒ 300 persons ‒ 200 M€ 2005‒2008 design study 2008‒2012 preparatory phase 2013‒2017 construction

Optical module (camera) 31 x 3” PMT Electronics inside

wet-matable connector (1) deep-sea network optical modulator lj+1 integrate timing system (GHz = ns) minimise offshore electronics penetrator (1) receiver lj receiver laser wet-matable connector (1) DWDM laser DWDM shore station

Needs new deployment technique Storey Frame Mechanical cable storage Data cable storage Mechanical cable connection Optical module 6 m Mechanical holder 1 Digital Optical Module = Dom 2 Dom’s on 1 bar = Dom-bar 20 Dom-bar’s on 1 tower = Dom tower Needs new deployment technique

Earth & Sea sciences short lived (rare) events dominate deep-sea life permanent observatory France Temperature Bioluminescence sudden Eddie currents food supply observatory time profile

KM3NeT deep-sea infrastructure 10 km3 two main electro-optical cables >100,000 PMTs, hydrophones, ACDP, seismometers, etc. <100 kW, 100 GB/s two main electro-optical cables 100 km, DC, 1 cupper conductor + sea return network PON, point-to-point + amplification new Ethernet standard Precision-Time-Protocol (”White Rabbit”) operation 10 years without maintenance

Issues, ideas, etc.

Deep-sea infrastructure materials containers (glass, Ti, Al) mechanics drag, deployment, etc. cables dry versus oil-filled little experience with vertical orientation wet-matable connectors expensive (combined fiber and cupper wires) bulky (problems with handling) penetrators source of single-point-failures (error propagation)

data taking & processing network high-bandwidth & long haul integration of data transmission & timing (PTP) (real-time) data distribution monitoring archival offline analysis (astronomy, etc.) external triggers satellites, other infrastructures computing (real-time) data processing algorithms (reduction of complexity & parallelization of problem) implementation (state-of-the-art OO-programming) hardware (multi-core, GPUs)

Fiber technology data transmission Energy transmission sensor laser/[A]PD flexible (2 x transceiver = point-to-point link) active feedback loop (intrinsically instable power, l) non-negligible electrical power consumption modulators wavelength, phase, intensity, polarization very low power reliable amplification long-haul communication Energy transmission ? sensor e.g. Bragg reflectrometer as deep-sea hydrophones sensitivity low weight…