Документ взят из кэша поисковой машины. Адрес оригинального документа : http://nuclphys.sinp.msu.ru/nseminar/antares_nemo.pdf Дата изменения: Tue Oct 25 18:10:20 2005 Дата индексирования: Tue Oct 2 00:23:15 2012 Кодировка: Поисковые слова: earth

ANTARES and NEMO ­ 3 Neutrino toward a km Telescope in the Mediterranean Sea
M.Taiuti
(University of Genova and INFN-GE)

Moscow 19 October 2005


OUTLINE


Introduction The ANTARES and NEMO project
Description Results Perspectives



Conclusions


Physics Motivations


High Energy Neutrinos are a powerful tool to investigate the hadronic mechanisms of Cosmic Ray production

Proton apparent direction Protons (below GZK limit) reach the Earth but the trajectories are deflected by the galactic and intergalactic magnetic fields

Cosmic accelerator

High energy gamma rays are absorbed by MWBG Neutrinos are not deflected nor absorbed


Physics Motivations
atmospheric muon ~5000 PMT

Cherenkov light

neutrino
muon Connection to the shore depth >3000m


Physics Motivations


A neutrino telescope in the Northern Hemisphere will provide:
Complementary sky survey to ICECUBE Overlap observation region with ICECUBE Study of the Galactic Center


Physics Motivation


The small cross section and the expected low neutrino flux require
large volume telescope ~ 1 km3 long observation time ~ yrs



The atmospheric muon background requires
a shielding > 2000 m water equivalent



The Mediterranean Sea provides convenient sites


The Sites
KM3 Mediterraneo
Pylos

BAIKAL DUMAND

La Seyne

Capo Passero

ICECUBE


The ANTARES Collaboration


Physics Institutes from:
France Germany Italy NL Spain Russia UK

NEMO



Sea biologists, geophysicists


The NEMO Collaboration
INFN


Bari, Bologna, Catania, Genova, LNF, LNS, Napoli, Pisa, Roma

Universities CNR

Bari, Bologna, Catania, Genova, Napoli, Pisa, Roma "La Sapienza"

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 involved


Technical Requirements


Issues to be solved to realize a km3 neutrino telescope in the Mediterranean Sea
Best site location (i.e. depth, water quality ...) Optical background from 40K-decay and bioluminescence Detector deployment Detector rigidity against sea currents Resistance to corrosion from salt water


The ANTARES Site


2400 m sea depth short path to the shore (40 Km) infrastructures (IFREMER,..) latitude : 42° 50' N

40 km submarine cable
-2475m


The ANTARES Detector
12 lines 25 storeys/line 3 PMTs /storey 900 PMTs

14.5 m


ANTARES Expected Performance
Effective area
depends on : reconstruction efficiency selection cuts absorption length

Angular resolution
below 10 TeV: dominated by - angle above 10 TeV: 0.2° after reconstruction


ANTARES ­ Sea Operations
Oct 01: main Electro Optical Cable Dec 02 : Junction Box Dec 02 : Pre-production Sector Line Feb 03 : Mini Instrumentation Line (MIL) (PSL)


The ANTARES Project




Mar 01: Sea bed survey Oct 01: Electro Optical cable deployment Dec 02: Junction Box (JB) deployed Dec 02 ­ Feb 03: Prototype Sector Line (PSL) & Mini Instrumentation Line deployed Mar 03: PSL and MIL connected to JB by submarine Jun 03: MIL & PSL recovered (diagnose: attenuation of the optical signal inside the mechanical electro optical cable of the lines) Mar 05: Line 0 & MIL deployed May 05 : Line 0 recovered (still attenuation of the optical signal inside the mechanical electro-optical cable of the lines due to a different reason) Oct 05: MIL still operating Oct 05: integration of Line 1 started with attenuation problem fixed Jan 06-Dec 07 : installation of the 12 lines


The NEMO Project


R&D phase (1999-2002)


Site selection and characterization R&D Activities

Several sites close to the italian coasts have been studied.

Feasibility Studies

Development of dedicated ASICS for the underwater front-end ASICS electronics Development of large area direction-sensitive optical modules All detector critical components and the deployment procedures have been examined A preliminary project for the km3 detector has been developed



Phase-1 and prototyping (2002-2006)

Realization and deployment of a prototype including all critical components Realization of an underwater infrastructure at -3500 m nderwater



Phase-2 (2006-...)


NEMO R&D Activity


Site location
More than 25 sea campaigns since 1998



NEMO-KM4
80 km off-shore 3500 m depth

80 km

NEMO-KM4


NEMO-KM4 Properties


High water transparency
Data compatible with pure salt ure water properties No seasonal variations



Reduced background, mostly from 40K decay
C ounting rates (kHz)

35

Base line rate (Threshold 1)

2.0%

25

1.0%

20

0.5%



Geologically stable

15 0 7 14 21 28

0.0%

Date (days since t he 31 of March)

st

35

42

49

Time above 200 kHz

10" PMT thres. 0.5 p.e. noise rate ~ 30 kHz Bioluminescence almost absent

30

1.5%


NEMO km3 Conceptual Design
Tower



Proposed lay-out
Secondary JB

10 junction boxes 81 towers 5832 PMTs

Primary JB

Electro-optical cable to shore

140-180 m

140-180 m


Expected Performance


Simulations show excellent angular resolution and sensitivity
NEMO
81 towers 140 m spaced 5832 PMTs


ICECUBE
80 strings 125 m spaced 4800 PMTs
Sensitivity to a E-2 neutrino spectrum from a pointlike source


Position-sensitive OMs


Cherenkov light is emitted at fixed angle
Knowledge of direction of incoming light reduces background and uncertainties



INFN Genova and MSU are collaborating to realize a prototype
4 anode PMT Mirror system
x
Photocathode Optical Gel

R
Mirrors


Shore station in the port of Catania

The NEMO Phase-1 Activity
The Catania test site: · 25 km off the coast of Catania · 2000 m depth · already equipped with a doubletermination cable
5 km e.o. cable 21 km e.o. cable with single steel shield Branching Unit

Geoseismic station SN-1 (INGV)

2.5 km e.o. cable with double steel shield

25 k m

Catania

TSN TSS
NEMO-KM4

5 km e.o. cable

80 k m

NEMO Phase 1


The NEMO Phase-1 Activity


Installation of the cable termination frames with electrooptical connectors



Deployment and connection of
Acoustic detection station INGV environmental observatory



Fully operational since January 2005


The NEMO Tower


Semi-rigid structure provides "easy" assembly, transportation and deployment
A 1:5 4-floor prototype has been successfully deployed and recovered in Spring 2004
16 floors

2 PMTs at each edge

16 m

A tower floor

"Folded" tower ready for transportation and deployment


The Tower Deployment


The NEMO Phase-2


Infrastructures for an -3500 m underwater site
Electro-optical cable (40 kW)
Purchase

80 km

NEMO-KM4

under way

Shore station in PortoPalo di Capo Passero
Building

under renovation

to NEMO-KM4


Conclusions and Perspectives


The ANTARES Collaboration is realizing a small scale (0.1 km3) neutrino detector in the Mediterranean Sea
Line 0 proved useful to solve problems related to datatransmission in high pressure environment Line 1 is being integrated It is expect to deploy the detector by the end of 2007


Conclusions and Perspectives


The NEMO Collaboration is working on a long-term R&D program toward a km3 -telescope in the Mediterranean Sea
An optimal candidate site has been found: NEMO-KM4 The NEMO Phase-1, aiming to validate the proposed technologies, is under way at the Catania Test Site


Since Jan. 2005 the geoseismic and acoustic stations are fully Sinc operative The completion is planned in the first half of 2006

The NEMO Phase-2, aiming to realize the deep sea station at NEMO-KM4, is in progress


The purchase of the electro-optical cable is in progress The set-up of the onshore station is in progress The deployment of a full-size tower is foreseen in 2007


Toward the -Telescope


EU is funding the joint activity for an Europeanscale Design Study for a km3 -telescope in the Mediterranean Sea
KM3NeT: ANTARES-NEMO-NESTOR consortium



2° VLVnT (Very Large Volume -Telescope) Workshop to be held in Catania (Italy) 8-11 Nov., 2005