The NEMO Project Neutrino Mediterranean Observatory P. Piattelli I stituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
NEMO Towards the km3 detector R&D phase (1999 - 2002) • – Site selection and characterization Several sites close to the italian coasts have been studied. A site close to Capo Passero (Sicily) at 3500 m with optimal water characteristics has been identified for the installation – R&D activities Development of specific ASICS for the underwater front end electronics Large area hybrid photomultipliers – Feasibility study of the km3 detector A complete feasibility study has examined all the detector critical components and the deployment procedures A preliminary project for the km3 has been developed • Phase 1: Advanced R&D and prototyping (2002 - 2005) – Realization of a detector subsystem including all critical components The system will be installed in Catania at the Underwater Test Site of the LNS Km3 detector realization (2006 ? - …) • NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
The NEMO Collaboration I NFN Bari, Bologna, Cagliari, Catania, Genova, LNF, LNS, Messina, Roma CNR I stituto di Oceanografia Fisica, La Spezia I stituto di Biologia del Mare, Venezia I stituto Sperimentale Talassografico, Messina I stituto Nazionale di Geofisica e Vulcanologia I stituto Nazionale di Oceanografia e Geofisica Sperimentale Universities: Bari, Bologna, Cagliari, Catania, Genova, Messina, Roma “La Sapienza” NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Site selection criteria • Proximity to the coast and to existing inf rastructures Easy access f or sea operat ions Reduct ion of cost s f or inst allat ion and maint enance • Distance f rom the shelf break and f rom canyons I nst allat ion saf et y • Depth Reduct ion of at mospheric muon f lux • Water optical transparency Opt imisat ion of det ect or perf ormances (ef f iciency and angular resolut ion) • Weak and stable deep sea currents Reduce st resses on mechanical st ruct ures • Low biological activity Low opt ical background (bioluminescence) ⇒ det ect or perf ormances Low biof ouling and sediment at ion on OM NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Site exploration activities • Since 1998 continuous monitoring of a site close to the coast of Sicily • More than 20 sea campaigns on the site to measure – water optical properties – optical background – deep sea currents – nature and quantity of sedimenting material • Other sites explored f or optical properties – Two sites in the Southern Thyrrenian Sea (Ustica and Alicudi) – Toulon (ANTARES site), in collaboration with Antares – Lake Baikal NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
The Capo Passero Site • Located in the South I onian sea • Selected af ter a screening of water optical properties in several sites close to the italian coasts • About 50 NM f rom shore (Capo Passero, Sicily) • Large and f lat area at about 3400 m depth • Far f rom important rivers NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
A km 3 detector in the Mediterranean NEMO Capo Passero - 36° 16’ N, 16° 06’ E NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Water optical properties Measure of profiles of water optical properties Temperature Salinity Attenuation Absorption Data taken in the South Thyrrenian Sea (Alicudi) Strong layering of waters The setup used (AC9+CTD) measures oceanographical (temperature, salinity, pressure) and optical (absorption and attenuation coef f icients at 9 wavelengths) parameters along the whole water column NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Water optical properties Seasonal dependence of optical parameters in Capo Passero • Seasonal dependence of oceanographical (Temperature and Salinity) and optical (absorption and attenuation) properties has been studied in capo Passero • Variations are only observed in shallow water layers Data taken in Aug 02 (3) March 02 (4) May 02 (2) December 99 (2) NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Water optical properties Seasonal dependence of absorption and attenuation lenghts • Values averaged in the depth region 2850÷3250 m and over several prof iles • No seasonal variations of absorption and attenuation lengths are observed in deep waters in the blue region ( λ = 440 nm) NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Water optical properties Comparison of NEMO and Antares data Optical water properties have been mesured in the summer 2002 in Capo Passero and Toulon in two joint NEMO- ANTARES campaigns • Absorption lengths measured in Capo Passero are compatible with optically pure sea water data • Large dif f erences between Toulon and Capo Passero are observed in the blue region Values measured with the • Antares Test 3’ setup are in good agreement with the AC9 data NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Optical background Sources of optical background • Decay of radioactive elements (mainly 40 K) → stable f requency noise (˜ 30 kHz on a 8” PMT at 0. 3 p. e. threshold) • Light produced by biological entities (bioluminescence) → random bursts with very high counting rate No luminescent bacteria have been observed in Capo Passero below 2500 m Data taken by I stituto Sperimentale Talassograf ico, CNR, Messina NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Optical background Comparison of Toulon and Capo Passero sites Data have been acquired with the same setup in Toulon and Capo Passero Capo Passero Noise on a 8” PMT 28. 5 ± 2. 5 kHz Toulon Noise on a 8” PMT 58 ± 3 kHz NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Seabed geology Core analysis • All the collected cores show the same stratigraphy • Some f eatures, associated to well known geological events, allow f or a dating of the cores • Only one evidence of a turbidity event is present, but it can be dated at about 60 kyr BP • The average sediment accumulation rate is estimated to be 3- 4 cm/ kyr NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Downward sediment flux Seasonal dependence of the mass flux • Two series of collected data span an interval of about 1 year 300 • The mass f lux is low (average of NEMO 1999 data 250 - 2 d - 1 ), as expected in an 62 mg m NEMO 2000 data oligotrophic enviroment such as 200 St. I1 1997 data the I onian Sea, with an strong TMF (mg m St. I1 1998 data 150 seasonal behaviour (spring bloom peak) 100 day • Data are comparable to those -2 -1 50 ) measured in the Northern I onian which show the same f eatures 0 J F M A M J J A S O N D • I nterannual variability can also occurr Data analysed by I stituto di Biologia del Mare, CNR, Venezia NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
The Capo Passero site Site optical and oceanographical characteristics • Absorption lengths (~70 m @440 nm) are compatible with optically pure sea water values • Measured values are stable troughout the years (important: variations on La and Lc will directly ref lect in changes of the detector ef f ective area) • Optical background is low (consistent with 40 K background with only rare occurrences of bioluminescence bursts) • The site location is optimal (close to the coast, f lat seabed, f ar f rom the shelf break and f rom canyons, f ar f rom important rivers) • Measured currents are low and regular (2- 3 cm/ s average; 12 cm/ s peak) • Sedimentation rate is low • No evidence of recent turbidity events NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
Development of a large area hybrid PMT Timing Timing Baikal New Design I. SIMION simulations show that shape of I. SIMION simulations show that shape of exisiting BAIKAL PMT can be improved to exisiting BAIKAL PMT can be improved to III. Coupling to a light provide one- one correspondence and provide one- one correspondence and guide system also timing improvement timing improvement provides information on the detected light direction II. Coupling to a position sensitive detector provides x information on the photoelectron emission R point NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
The LNS Underwater Test Site Long term tests for: underwater connections, electronics, mechanical structures, optical and acoustic detectors. Multidisciplinary laboratory (will host an on-line underwater seismic station of the I stituto Nazionale di Geofisica e Vulcanologia) SHORE SHORE LABORATORY LABORATORY UNDERWATER UNDERWATER STATION STATION NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
The LNS Underwater Test Site Layout of the installation GEOSTAR Drop cable 2 Drop cable 2 5.220 m 5.220 m 2.330 m joint Double Armed Cable BU joint joint 20.595 m Single Armed Cable Drop cable 1 Drop cable 1 5.000 m 5.000 m Cable features: Cable features: NEMO Phase 1 Lab � 10 Optical Fibres standard ITU-TG-652 � 6 Electrical Conductors Φ 4 mm 2 NEMO P. Piattelli, HENA Workshop, Paris, june 16-17, 2003
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