Isabella Amore Laboratori Nazionali del Sud - INFN, Catania International School of Cosmic Ray Astrophysics 15th Course: "Astrophysics at Ultra-high Energies" NEMO: a project for a km3 underwater detector for astrophysical neutrinos in the Mediterranean Sea Isabella Amore June 2006, Erice Ettore Majorana Centre

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania Why Neutrino Astronomy? gammas 0,01-1 Mpc protons E>10 19 eV 10 Mpc High energy neutrinos Astrophysical source We want to measure neutrinos coming from astrophysical sources 1 parsec (pc)  3 ligth years 5 Gpc Closest AGNs Galactic radius (15 kpc) TeVPeVEeV Neutrinos traverse space without being deflected or absorbed: – They can reach the Earth from cosmological sources – They point back to their sources – They allow to view into dense environments

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania Status of collaborations BAIKAL, AMANDA: taking data NESTOR, ANTARES, NEMO R&D:under construction ICECUBE: completion expected in 2010 KM3NET – Mediterranean : EU Design Study AMANDA ICECUBE BAIKAL ANTARES 2400 m NESTOR 3800 m NEMO 3500 m In order to obtain the whole sky coverage 2 telescopes must be built The Galactic Centre is observable only from the Northern Hemisphere Small scale detectors and demonstrators km 3 scale telescopes

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania The NEMO collaboration INFN Bari, Bologna, Catania, Genova, LNF, LNS, Napoli, Pisa, Roma Universities Bari, Bologna, Catania, Genova, Napoli, Pisa, Roma “La Sapienza” CNR Istituto di Oceanografia Fisica, La Spezia Istituto di Biologia del Mare, Venezia Istituto Sperimentale Talassografico, Messina Istituto Nazionale di Geofisica e Vulcanologia (INGV) Istituto Nazionale di Oceanografia e Geofisica Sperimentale (OGS) Istituto Superiore delle Comunicazioni e delle Tecnologie dell’Informazione (ISCTI) More than 70 researchers from INFN and other Italian Institutes

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania NEMO R&D activities towards the Mediterranean km 3 Site selection and long term monitoring Feasibility study of the km 3 detector Installation of small scale prototypes Realization of a marine infrastructure for the km3

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania The Capo Passero deep sea site It is located in a wide abyssal plateau far from shelf breaks and geologically stable. The average depth is 3500 m, the distance from shore is about 100 km. Optical properties of deep sea water are the best measured among investigated sites (absorption length close to optically pure water astro-ph\ ) Optical background is low (30 kHz on 10’’ PMT at 0.3 s.p.e. threshold) and mainly due to 40 K decay since the bioluminesce activity is extremely low. Underwater currents are very low (2.5 cm/s) and stable. After eight years of activity in seeking and monitoring abyssal sites in the Mediterranean Sea the NEMO collaboration has chosen a deep sea site about 100 km SE of Capo Passero, in Sicily. The site has been proposed to ApPEC on january 2003 as candidate site for the installation of the km 3.

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania Seawater optical properties Optical properties have been measured in Capo Passero since 1998 Profiles as a function of depth of oceanographic and optical properties 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 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 Absorption lengths measured in Capo Passero are close to the optically pure sea water data Differences between Toulon and Capo Passero are observed for the blue light absorption Absorption lengths measured in Capo Passero are close to the optically pure sea water data Differences between Toulon and Capo Passero are observed for the blue light absorption temperature salinity a440 c nm 440nm L c =35.5 m L a =66.5 m

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania Optical background was measured in Capo 3000 m depth. Data are consistent with 30 kHz background on 10”PMT at 0.3 spe (mainly 40 K decay, very few bioluminescence). Optical data are consistent with biological measurements: No luminescent bacteria have been observed in Capo Passero below 2500 m Optical background in Capo Passero 40 K Baseline rate~ 30 kHz

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania Feasibility study for the km 3 detector Detector architecture has been studied in order to Reduce the number of structures to reduce the number of underwater connections and allow operation with a ROV Detector modularity 9 x 9 = 81 “Towers” with 3 dimensional and non homogeneous distribution of sensors Conceptual detector layout

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania The NEMO tower Height: compacted15:20 m total750 m instrumented600 m n. beams16 to 20 n. PMT64 to 80 Beams: length15 m spacing40 m The tower is a semi-rigid 3D structure designed to allow easy deployment and recovery. High local PMT density is designed to perform local trigger. 750 m 10’’ PMTs

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania Expected detector performaces Sensitivity Sensitivity to a E v -2 neutrino spectrum from point like sources NEMO81 towers 140m spaced PMTs IceCube80 strings 125m spaced PMTs Geometry “flexibility” Effective area for different detector geometries spacing towersfloors 140 m40 m 300 m40 m C. Distefano, NEMO, astro-ph/ R. Coniglione, NEMO astro-ph/

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania Validation of technologies: NEMO Phase 1 The NEMO Collaboration is undergoing the Phase 1 of the project, installing a fully equipped deep-sea facility to test prototypes and develop new technologies for the km 3 detector. Shore laboratory port of Catania e.o. cable from shore TSS Frame To be completed in 2006 Junction Box NEMO mini-tower (4 floors) Deployed on Jan 2005 underwater e.o. cable 10 OF 6 conductors Underwater test site: 25 km E offshore Catania at 2000 m depth Realizaton of a system hosting all key elements for the km3 detector: Mechanical structures; Optical and environmental sensors; Electronics; Data transmission system; Power distribution system; Acoustic positioning system;Time calibration system

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania Sea operations January 2005

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania The NEMO test site: a multidisciplinary laboratory The O DE station GEOSTAR SN-1 deep sea station First data from 2000 m GEOSTAR SN-1, a deep sea station for on-line seismic and environmental monitoring by INGV. The NEMO test site is the Italian site for ESONET (European Seafloor Observatory NETwork); O DE (Ocean noise Detection Experiment), for on-line deep sea acoustic signals monitoring (4 hydrophones hydrophones 30 Hz - 40 kHz  measurement of noise bkg for neutrino acoustic detection ).

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania The NEMO Phase 1: the underwater station TSS Frame Junction Box NEMO mini-tower (4 floors, 16 OM) 300 m Mini-Tower compacted Mini-Tower unfurled 15 m Al alloy Buoy e.o. connection The mechanical structure is under final assembly at the NEMO Test Site shore laboratory

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania The Junction Box Fiberglass external vessel Power vessels electro-optical connectors The Junction Box hosts the data transmission and power distribution system. The JB is made of an Al cage, an extrenal fiberglass vessel and 4 steel pressure vessels: PV1, PV2, PV3 and Trafo Vessel. The space between fiberglass and PV will be filled with silicone oil. This solution permits to separate the corrosion and the pressure resistance problems. 1 m

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania NEMO Phase 1: Floor DAQ chain Hamamatsu 10" R7081 SEL 200 Msample/s Floor Control Module Board: Transmit OM and slow Control data (water parametres, OM position, internal sensors) to shore through Optical Fibre (DWDM technology) Optical Module (OM) PMT tubeFEM board Underwater electrical Cable e.o. transceiver Floor Control Module Board (FCMB) Optical modules Floor control module

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania The NEMO Phase 2 project in Capo Passero Objectives -Realization of an underwater infrastructure at 3500 m on the Capo Passero site -Test of the detector structure installation procedures at 3500 m -Installation of a 16 storey tower -Long term monitoring of the site Status -The EO cable (≈48 optical fibres, 30÷40 kW) will be deployed within The shore laboratory acquired, now in restoration

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania Summary and outlook Site selection –The Capo Passero site has been deeply studied: the results show that it is an excellent location for a km 3 telescope Feasibility study –All the critical detector components and their installation have been analysed in detail Present activity –NEMO-Phase 1 in Catania: installation of a subset of the detector including all the critical components Future plans –NEMO-Phase 2 : Underwater 3500 m in Capo Passero … A large international collaboration will build the Mediterranean km 3

Isabella Amore Laboratori Nazionali del Sud - INFN, Catania We are eagerly waiting for the start-up !