Els de Wolf, Nikhef/UvA KM3NeT WP345-meeting 23 February 2009 The SeaWiet project SEnsor Architecture for a WIde Energy range Telescope Els de Wolf, Nikhef/UvA KM3NeT WP345-meeting 23 February 2009

Outline KM3NeT DS objectives and constraints Companies consulted Starting points in 2006 for design Choices made: - Site - Physics Detector geometry Budget constraints - OM - Storey Detection Unit DU deployment method Readout/DAQ

KM3NeT DS objective and constraints Design a facility with a cubic kilometre scale telescope in the Mediterranean Sea to detect neutrinos from point sources, GRBs, DM,…. with a budget ~ 200 MEuro ESFRI: costs 220-250 MEuro

Companies consulted PMT Photonis (30 PMTs for free, bought about 80) DU e/o cable Sea Proof Solutions Seacon (bought reference DU e/o cable) TKF JDR (also MEOC) (order feasibility study?) OM Nautilus (bought spheres) Optronics (ordered feasibility study application of coatings) Readout DAQ Van der Hoek Photonics (consultant photonic technology ) (TU/e), Cobra Institute CIP Ltd (bought feasibility study and a reference model 10 Gb/s readout/DAQ) Acreo Corning (bought fibres) Power system PBF(order feasibiliy study?)

Starting points 2006 Site Single site, no preference for location SeaWiet: design for 100 km from shore, 5 km deep and Antares-bioluminescence rates and remote operation Indonesia

Starting points in 2006 Physics Broad energy range (DM – cosmogenic neutrinos), excellent angular resolution (CDR), largest possible effective area m 800m 1400 m SeaWiet: large ring with - empty core - ‘thickness’ ~ Antares large height OMs looking upwards homogeneous distribution of OMs

Subject to change according simulation results Geometry parameters Simulation (WP2, Oct 2008) Technical design (Nov 2007) Hexagonal geometry 95 m between DUs 25 m between storeys (30) 21 storeys (20) Total length DU 600 m (670) 154 DUs Volume < 1 km^3 Not a fixed geometry 95 m between DUs 25 m between storeys 21 storeys Total length DU 600 m 300 DUs Volume > 1 km^3 Subject to change according simulation results

Starting points in 2006 Budget constraints SeaWiet: optimise Build a detector with the largest effective area for the specified amount of money (200-250 MEu) SeaWiet: optimise cost of storey # sea operations ANTARES KM3NeT Total costs 25 M€ 220-250 M€ #total storeys 300 6300 Cost per storey)* 83 k€ 40 k€ Factor ~2 cheaper )* incl. R&D and sea operations

Starting points in 2006 Storey SeaWiet: OM=Storey multiPMT OM Photocathode area ~ amount of an Antares storey Excellent two photon separation (random background rejection) Looking upwards (atm. muon background rejection) Simple mechanical structure No separate electronics container (No separate instrumentation container) physics money SeaWiet: OM=Storey multiPMT OM

OM parameters 10 stage Photonis, Concave front Bialkali cathode, Q.E. 42% 31 PMTs (3”) in 17” glass sphere 19 in lower hemisphere 12 in upper hemisphere PMT base < 30 mW Request Erlangen to investigate with other PMT manufacturers

Design OM=Storey

OM assembly 31 x 3” PMTs Low power base (< 30 mW)

Status OM (talk Eric Heine in WP3 session) Test with PMTs in lower hemisphere in dark water basin with K40 (just started) PMT base being further optimised 1st mechanical reference model finished Assembly procedure Cooling test 2nd mechanical reference model being prepared Further optimisation Verification of assembly model for production

Storey parameters Storey electronics included in glass sphere (talk of Jelle Hogenbirk in WP4 session) Room for acoustic detectors, tilt meters, compasses inside glass sphere Mechanical structure is a ‘ring’ of composite material attached to two parallel aramide ropes in de DU mechanical structure (talk of Eric Heine in WP5 session)

Starting points in 2006 DU (String concept) Minimise # pressure transitions Ready-to-deploy assembly method Compact deployment No maintenance SeaWiet: oil filled flexible e/o cable, equi-pressure operation, break-out-box per storey, pressure transition at OM and at SJB only

Details being worked out together with NIOZ DU layout Oil filled e/o cable (OD ~10 mm) 21 fibres, 2 copper wires 2 parallel aramide ropes (OD ~4 mm) Details being worked out together with NIOZ Breakout-box Master Module (DWDM) (operation in oil under pressure, being investigated) e/o interlink cable to SJB (2 fibres)

DU e/o cable reference model 3 break-outs 40 fibres, interlinked (400 m) 6 copper wires 2 fibres+2 wires at each break-out Manufactured by Seacon

Pressure test at NIOZ 40 fibers interlinked (400 m) Large connector broke at 300 bar Fibres performed as expected

Status DU e/o cable Reference model tested at 1 atm: OK In pressure tank at NIOZ: Part of the large 40 fibre connector broke at 300 bar Fibres performed as expected Next steps Meeting with Seacon in March Adapt cable closer to foreseen design Remove 40 fibre connector Repeat pressure test (600 bar)

Parameters DU e/o cable Oil filled flexible hose OD ~10 mm 21 fibers, one for each storey 2 conductive copper wires Break-out-box with fuses at each storey (failure of storey should not propagate) Either connector in BOB or splice during assembly (under investigation)

DU deployment method Need for experts ANTARES KM3NeT #lines 12 300 Deployment period 2 year 4 year #deployments/yr 6 75 Factor ~13 faster )* incl. R&D and Sea operations Need for experts

Status DU deployment method (talk Eric Heine in WP5 session) NIOZ involved in development since Jan 2009 Compact deployment Simultaneous deployment of many DUs DUs may be interconnected into a sector before deployment Optimisation studies started NIOZ plans tests in 30 m height water basin

Starting points in 2006 Readout/DAQ All-data-to-shore concept (GRBs, flexible triggering) Sensor concept: small # active components off-shore (readout is equivalence of lemo-cable) Point-to-point optical connection shore-OM SeaWiet: 10 Gb/s fibre technology, built in timing calibration, front-end electronics on shore

10 Gb/s data transmission Sub-sea station (DWDM+modulator) Fiber to shore 100 km (ms signal propagation) Shore station (CW-laser) SPARK, DAQ reference model built by CIP Ltd

10 Gb/s data transmission Requirement achieved: rigid timing (<10 ps)

Read/DAQ architecture (talk Jelle Hogenbirk in WP4 session) Timing calibration similar to Antares system: Laser on-shore Light pulse reflected at each OM Time-stamp added on-shore No separate fibre+electronics off shore On shore -Ethernet access to each OM/Storey Off-shore PMT data collection Integrated Timing and Trigger Control Slow Control enables Ethernet based bi-directional data transfer

Status Readout/DAQ (talk Jelle Hogenbirk in WP4 session) SPARK, reference model built by CIP Ltd Shore station + Subsea station (DWDM+modulator) Result: rigid timing (< 1 ps) over 100 km 10 Gb/s technology is feasible for KM3NeT architecture Node Development Kit under construction For development of node interface configuration (OM, instrumentation, …) Storey logic inside OM can be considered to be controlled by single Ethernet node which is physically on-shore Logical layer is provided between primary OM functions and the Ethernet node

Summary Site: single site, no preference Physics: aim for wide energy range Detector geometry: simulations needed Budget constraints: largest volume for 200-250 MEu Storey=OM Configuration of 31 PMTs (3”) fixed Low power PMT base is according specs, further optimised 1st mech. ref. finished: cooling according specs 2nd mech. ref. model: verify assembly planning K40 measurements with PMTs in hemisphere just started

Summary DU DU deployment method Equi-pressure operated e/o cable with break-out-boxes Cable to be adapted and pressure tested again Operation of DWDM under pressure under investigation Mechanical design together with NIOZ DU deployment method NIOZ involved Compact deployment Tests planned in 30 m height water basin

Summary Conclusion: design well on its way, no show stoppers Readout/DAQ 10 Gb/s technology proven Rigid timing (< 1 ps over 100 km) shown (SPARK) Node Development Kit under construction Conclusion: design well on its way, no show stoppers