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Antares Project Status Report

Overview of the Antares deep-sea neutrino telescope project, including detector layout, design, electronics, trigger system, sea operations, successes, challenges, and future plans.

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Antares Project Status Report

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  1. Status report on the Antares Project http://antares.in2p3.fr Bertrand Vallage – DSM/Dapnia/CEA-Saclay on behalf of the ANTARES Collaboration 13th International Symposium on Very High Cosmic Ray Interactions Pylos,6-12 September 2004

  2. Detector layout a storey Horizontal layout 12 lines (900 PMTs) 25 storeys / line 3 PMTs/storey 14.5 m 350 m 40 km to shore 100 m Junction box ~70 m Readout cables Sea bed ~ -2500 m

  3. Base LED PMT m-metal cage Gel Detector design: Optical Module • Transit Time Spread < 3.6 ns Blow-up of an Optical Module Sensitive area  500 cm2 • Peak/Valley > 2 SPE peak : Valley : PMT: 10”Hamamatsu R7081-20 900 PMT’s have been fully characterized The Optical Modules are being assembled

  4. LCM_CLOCK LCM_DAQ ARS_MB x 3 COMPASS_MB Detector design: Local Control Module Electronics of a Local Control Module : LCM’s connected by Electro-Optical Cable carrying power, clock (20MHz) and Data (1Gb/s per line) All electronic boards designed and at the (pre)production stage

  5. Trigger and DAQ ‘4’ levels trigger : • “SPE” • “Complex” L0: Pulse Shape Discriminator threshold ~ 1/3 photo-electron • “Analog Ring Sampler” providing digitized integrated charge (→ ~ 20 photo-electron), time (250ps), timestamp(25ns) @ 20Mb/s • For high amplitude or high duration hits (~2%), a GHz flash ADC mode can provide thefull waveformof the signal (limited to low rates) Oscilloscope mode on double pulse each optical module will provide at least 60 kHz of data ! (40K & biolum) L1: In case of continuous high rate in excess of 200kHz, a local trigger coincidence at the storey level (3 optical modules) can be activated (L2: coincidence between storeys → not necessary if 1Gb/s/line) L3: time slice filtering on-shore on a farm of PC’s Global philosophy : ALL DATA TO SHORE !

  6. Sea operations 2001-2003 Electro-optical cable - Oct 2001 Castor Junction box immersion - Dec 2002 Nautile (Ifremer) Sector line - Dec 2002 Connecting lines to JB - Mar 2003

  7. Prototype Lines operated in 2003 Mini Instrumentation Line (MIL) Feb 2003 Prototype Sector Line (PSL) Dec 2002 Dec 2002 March 2003

  8. The ‘dark room’ Prototype Sector Line for 2003 Amplitude calibrated and time delays adjusted with laser in ‘dark room’→σt ~ 0.9-1.2 ns

  9. Rates and burst fraction of PSL Pb: the fiber transmitting the clock failed at the bottom of the line…→ no muon track reconstruction (was performed in 2000 with demonstrator) Large variability of rates ! 90% below 200kHz, local trigger ?

  10. 10 8 tilt w/ vertical 6 Current velocity (cm.s-1) LCM1 4 2 0 Tilt (o) Position monitoring of PSL and MIL Compass heading and current velocity correlation : Movements of the storeys synchronized: the PSL moves as a solid The line is essentially vertical (average tilt ~ 0.2°)

  11. Experience acquired by Line operations Successful achievements : • Complex marine operations : • line deployments and accurate landing (few meters) • line remote release and recovery • sea-level connexion of Junction Boxto Electro Optical cable • underwater connexion of lines to Junction Box • Junction Box operational :power distribution validated, very stable behaviour • Remote detector control and DAQ systems completely functional • Readout and data-transfer over Electro Optical cables qualified :data recorded during 3 months of Line operations (OMs rates, slow-control parameters, compass…)

  12. Shrunk tube Experience acquired post-recovery 2 main problems encountered, being corrected : • • Collapse of the plastic tube around the Master Clock optical fibre→no clock distribution along the Line under pressure • Consequences: no correlated data between storeys, no acoustic positioning, … → no muon track reconstruction Remedy: use cables with steel tubes protecting the optical fibres, as foreseen in the original cable specifications

  13. connector pressure -0.26mm Ti container Experience acquired post-recovery • Water leak due to O-ring failure in one MIL electronics container : happened 2 months after immersion Consequence : line flooded and communication lost ! Cause: misunderstanding with connectormanufacturer … Remedy : different connectors with larger safety margin

  14. Summary • Very useful experience acquired with operation and post-recovery analysis of PSL and MIL:detector concept & deployment techniques validated, problems understood & fix implemented, reimmersion of both improved lines for Xcheck end 2004 • Production of all detector elements is ongoing : quality control enforced in many production stages,deployment of main EO cable & Junction Box completed, full detector will be deployed 2005-2007 • The ANTARES project is an important step towards a KM3 detector in the Mediterranean Sea…

  15. Next slides are spares

  16. 1.0 For  > 90º the transmission loss in 1 year was smaller than 1.5% 0.5  0.0 Antares site properties R&D since 1996 : ~50 deployments of autonomous strings : Water transparency: Blue light (470 nm) abs ~ 608 m lscat eff ~300 m UV light (370 nm) abs ~ 262 m l scat eff ~ 100 m Transmission (normalized to immersion date) 1.0 0.9 0.8 Temperature (13.2°C) and salinity are stable: stability of refractive index 0.7 0.6 Sources of background: radioactive decay of 40K & bioluminescence : Base line ~ 60 kHz for 10” PMT 5% of time above 200kHz 0.5 0.4 Current: dominant East ↔ West on average 6 cm.s-1 exceptionally 15 cm.s-1 Biofouling Days from July 12, 1997 250 days total

  17. m n Expected performances : resolutions Below 10 TeV, dominated by θfrom interaction kinematics. Limited above 10 TeV by PMT Time dispersion and diffusion in water : σθ~ 0.2° From dE/dx : RMS(Erec/EMC) ~ factor 2-3 Used for cosmic/atmospheric  separation

  18. Expected performances: effective area (Includes reconstruction efficiencies, selection cuts, …) Detector response to muons 0.01-0.07 km2 For when entering Earth 1-20 m2 Drop at high energy for upgoing neutrinos due to Earth opacity

  19. Optical beacon t2 t3 t1 time adjustment Cylinder Optical fibres t0 Mini PM Laser Optical Splitter Time difference (ns) Time delays adjustment in dark room Time calibrations in dark room :σ~ 0.9-1.2 ns

  20. Muon reconstruction during R&D 2000 7 PMTs looking @ 90° zenith angle relative positioning accuracy ~5 cm

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