NESTOR – a status report

Presented by Petros A. RapidisNational Center foir Scientific Research “Demokritos”

Athens, GreeceOn behalf of the NESTOR collaboration

Describing the work of many, and also the work of others

Neutrino Extended Submarine

Telescope with Oceanographic

Research

Presented on April 22, 2008 at the 3rd Workshop on Very Large Volume Neutrino Telescopes (VLVnT08),

at Toulon, France, April 22-24, 2008

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Germany

University of Hamburg University of Kiel

          

Greece

 University of Athens

National Observatory of Athens – NESTOR Institute for Deep Sea Research, Technology and Neutrino Astroparticle Physics

University of CreteNCSR “Demokritos”

Hellenic Open University Aristotelian University of Thessaloniki

University of Patras University of Thessaloniki

                    

Russia

Bureau of Oceanological Engineering  & Institute For Nuclear Research, Russian Academy of Sciences

Sholokov Open University

          Switzerland

University of BernCERN

          U.S.A.

University of HawaiiLawrence Berkeley National Laboratory

Outline:

A description of the NESTOR project

A few words about the 2003 run and what we learned from this

Plans for the future :

• The NuBE proposal• Site studies• Deployment work

Toulon4500 m - 5100 m

2400 m

3500 mCapo Passero Pylos

The area off the coast of the Southern Peloponnese easternmost and deepest of the three areas under consideration

s

Also a very versatile and convenient area

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32 m diameter

30 m between floors

NESTOR TOWERNESTOR TOWER

144 PMTsEnergy

threshold as low as 4 GeV

20 000 m2

Effective Area

for E>10TeV

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Original ideas about a NESTOR full detector

~4,000m from the surface

~400m

Driven by the assumption that one has to minimize the wet-mateable connections

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• Hamamatsu PMT R2018-03 (15”)

• Benthos spheres

• μ-metal cage

• power supply

The 2003-Detector

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The Cable Deployment:The Cable Deployment:

June 2000June 2000

ElectroOptical cable to shore (18 fibers +1 conductor)

Deployed in June 2000 by the cableship MAERSK-FIGHTER (ALCATEL- TELEDANMARK)

Cable was damaged during laying because of ship’s problems.

Cable landing has been completed and first three km have been buried 2 m inside the bottom sand.

NESTOR Star Deployment (March 2003)

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Coincidence rate for OMs as measured at a depth of 3800m with 1pe thresholds The points represent the data, the solid line the Monte Carlo estimation including background and the dashed line the Monte Carlo estimation for the contribution of the atmospheric muons.4 fold rate is 0.25 Hz for this 12 PMT node.

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single p.e.

LED Run

single p.e. pulse height distribution

two p.e.s pulse height distribution

dark current pulse height distribution

sum of the above

Data from a depth of 3800 m

PMT Pulse Height Distribution

Calibration

K40 Background: A stable calibration source

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Event 1785 – Run 81 – BFile 3

c

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Event 1785 – Run 81 – BFile 3

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The measured vertical muon intensity I0

and the index , at a depth of 3800 m water equivalent, are

Looking to the future….

What can we do before the big one comes in ?!

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Signal transmission & ControlShore Laboratory Power supply

PMT signal transmission

low voltage supply (24V) control and monitoring signal transmission

Ti-Sphere ElectronicsTi-Sphere Electronics Triggering Digitization Event Formatting Controls

Slow Controls

Calibration Unit

Theodore Athanassopoulos’ anti-talk

NuBE - NESTOR

a

• a

…meanwhile …

GRB duration is of the order of 100 seconds

300 m

Neutrino Burst Experiment – a quick look for AGN – very high energy neutrino coincidences

Two cluster NODE

This drawing is to scale

Some simple considerations : Cherenkov light produced for 1 cm in water is ~200 photons in the 350-550 nm range

Let us consider the case of a 100 TeV ( 1014 eV)Range in water (km) = 4.0 x ln (1+E(TeV)) (i.e. 10 TeV ~ 9 km, 100 TeV ~ 18 km )

Thus a on the average is accompanied by a ‘bundle’ of particles - 100 TeV / (18 km x 1 MeV/cm) ~ 60 particles (assuming they are minimum ionizing and have a de/dx of 1 ~MeV/cm) (n.b. a better simulation gives 77 particles)

In passing: a 100 TeV electron (e.g. from from NC interaction, and given Xrad = 36 cm) will give rise to a dense shower with a length of L ~ 10 m , i.e. ~40 000 particles. Also a is quite similar to an electron or muon

The Optical Module is a 37 cm diameter sphere.In a 37 cm length with 200 ph/cm there will be ~ 10^4 photons produced by a 100 TeV

Light at a node 300 m away –Project to a cylinder A=2 R(300m)L(37cm) ~ 6x106 cm2

Thus we have 0.0015 photons/cm2 and for a 15" PMT of cathode area of 1080 cm2

We expect 1.5 photoelectrons. Now let us use a quantum efficiency of 20% and an overall efficiency for transmission losses, reflections in the glass etc. of 50% and take into account that the node has 16 OM’s 2.4 photoelectrons per node, i.e. can be seen !

As shown earlier at a depth of 4 km with the floor of NESTOR (12 OM) the 4-fold rate is .25 Hz for downgoing m. Thus for a 16 OM node it is ~1 Hz.For an active window of 3 s rate 1Hz x 1Hz x 3x10-6 s = 3x10-6 s-1 or 3x10-4 in 100sGRB are ~300 per year = 10-5 s-1 or 10-3 in 100 s

So for a 100 s window fake is 3x10-4 x 10-3 = 10-7 in a year long run is the fake rate.

At 100 TeV neutrinos begin to be absorbed by the earth, thus one has to start looking up.

So the crucial question is : can you handle the flux of downgoing cosmic ray induced muons ?

Waxman paper says that there should be 10-100 of 1014 eV per GRB for 1km2

So we can hope for 5-50 of such events per year (or more if the situation is more favorable).

2 node trigger with E>65 GeV for passing between stings nodes

Figure 1, LIMS Glass Housing and the steel and Etalon construction. Light source positions are shown (A')

Picture 1, LIMS Glass Housing and the steel

Figure 3

Light Absorption Measuring System

To study sedimentation – fouling …

Autonomous – complements sediment trap studies.

Continuation of Site Studies

Summary of sediment trap studies

Bioluminescence work

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See J. Graig’s talk tomorrow

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Atlantic

Antares Nestor

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Pylos 4500 m deep site

Pylos 5200 m deep site

Extensive measurements of deep sea currents

The deep currents have very low velocities that rarely exceed 6 cm/s. In general, the flow at the Pylos site of 4500 m depth is northward and 90% of the time is below 4 cm/s, and at the 5200 m deep site is southward but substantially weaker, with 95% of the time the current speed being below the instrument’s measurement threshold

Light transmission in the water

Older measurements (See Uli’s talk)

Is there a significantdependence ?Published data for ‘pure’ water …

For= 460 nm

=300nm =700nm

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A. Psallidas , NESTOR

Light Intensity Measuring System

● 2 Sources: 8 LEDs in 2 groups 1. 375nm, 420nm, 450nm, 495nm 2. 383nm, 400nm, 470nm, 525nm● Detector: 2 Photodiodes Area: 18 mm x18 mm Type: Hamamatsu S633701● Distances between source and detector: 10 m, 15 m, 17 m, 22 m.

Data just on board of the RV Aegeon ! Looks good ! But not fully digested yet ….

The talk that was not meant to be ….

The Delta-Bereniki deployment platform

A versatile dedicated vessel

Under reconstruction – engines are mounted and she will be re-floated soon. (In a month ?)

Was built to allow assembly of towers - but she is a lot more versatile.

FREQUENCY (%) OF WIND STATE IN BEAUFORT SCALE FOR METHONI AREA. PERIOD 1956-2001

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Heave compensated crane bridge.

She will be able to hold position and allow work up to the end of Beaufort scale 4 sea (frequent white horses, 30 km/hour wind, 1 m waves)

A. Belias – Proposal for a reconfigurable data acquisition system for KM3NeT (09:30 ENG)

M. Stavrianakou - First ideas for KM3NeT on-shore data storage and distribution (12:50 PHYS)

S. Koutsoukos – NuBE Calibration from 10s to 100s of meters in an underwater neutrino telescope (15:45 ENG)

T. Athanassopoulos – Commodity , FPGA based front end electronics for an underwater neutrino telescope (09:10 ENG)

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A. Psallidas - Very recent measurements of light transmission in sea water in the Pylos area

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And the talk that was not meant to be ….