NESTOR – a status report Presented by Petros A. Rapidis National Center foir Scientific Research “Demokritos” Athens, Greece On behalf of the NESTOR collaboration Describing the work of many, and also the work of others N eutrino E xtended S ubmarine T elescope with O ceanographic R esearch Presented on April 22, 2008 at the 3rd Workshop on Very Large Volume Neutrino Telescopes (VLVnT08), at Toulon, France, April 22-24, 2008

2 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 Crete NCSR “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 Bern CERN U.S.A. University of Hawaii Lawrence 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

Toulon 4500 m m 2400 m 3500 m Capo PasseroPylos 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

6 32 m diameter 30 m between floors NESTOR TOWER 144 PMTs Energy threshold as low as 4 GeV m 2 Effective Area for E>10TeV

7 Original ideas about a NESTOR full detector ~4,000m from the surface ~400 m  Driven by the assumption that one has to minimize the wet-mateable connections

8 Hamamatsu PMT R (15”) Benthos spheres μ-metal cage power supply The 2003-Detector

10 The Cable Deployment: June 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.

13 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 K 40 Background: A stable calibration source

14 Event 1785 – Run 81 – BFile 3 c

15 Event 1785 – Run 81 – BFile 3 c

The measured vertical muon intensity I 0 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 ?!

20 Signal transmission & Control Shore Laboratory Power supply PMT signal transmission low voltage supply (24V) control and monitoring signal transmission Ti-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 nm range Let us consider the case of a 100 TeV  ( 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 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 X rad = 36 cm) will give rise to a dense shower with a length of L ~ 10 m, i.e. ~ 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) ~ 6x10 6 cm 2 Thus we have photons/cm 2 and for a 15" PMT of cathode area of 1080 cm 2 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 100s GRB are ~300 per year = s -1 or in 100 s So for a 100 s window fake is 3x10 -4 x = 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  of eV per GRB for 1km 2 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

Light Absorption Measuring System To study sedimentation – fouling … Autonomous – complements sediment trap studies. Continuation of Site Studies Summary of sediment trap studies

Bioluminescence work See J. Graig’s talk tomorrow

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 significant  dependence ? Published data for ‘pure’ water … For  = 460 nm =300nm =700nm Absorption Coefficient (m -1 )

A.Psallidas, NESTOR Light Intensity Measuring System ● 2 Sources: 8 LEDs in 2 groups nm, 420nm, 450nm, 495nm nm, 400nm, 470nm, 525nm ● Detector: 2 Photodiodes Area: 18 mm x18 mm Type: Hamamatsu S ● 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.

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) A. Psallidas - Very recent measurements of light transmission in sea water in the Pylos area Unpaid Advertisement And the talk that was not meant to be ….