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Moscow, 18.10.2005

The Baikal neutrino telescope: Physics results and future plans. V. Aynutdinov, INR RAS for Baikal collaboration. Moscow, 18.10.2005. Collaboration. Institute for Nuclear Research, Moscow, Russia. Irkutsk State University, Russia.

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Moscow, 18.10.2005

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  1. The Baikal neutrino telescope: Physics results and future plans V. Aynutdinov, INR RAS for Baikal collaboration Moscow, 18.10.2005

  2. Collaboration • Institute for Nuclear Research, Moscow, Russia. • Irkutsk State University, Russia. • Skobeltsyn Institute of Nuclear Physics MSU, Moscow, Russia. • DESY-Zeuthen, Zeuthen, Germany. • Joint Institute for Nuclear Research, Dubna, Russia. • Nizhny Novgorod State Technical University, Russia. • St.Petersburg State Marine University, Russia. • Kurchatov Institute, Moscow, Russia. BAIKAL in CernCourier 7/8-2005

  3. Outline: Baikal A N N Neutrino telescope NT200 (1998) Design Physics Results (selected) : NT200 upgrade -> NT200+ (2005) New Design Calibration (new laser) Perspectives: Gton scale detector (GVD) at Baikal NT200+ as a basic cell of future Gton detector Summary Motivation Present telescope configuration is perfect test facility for future Gton detector Amanda/IceCube

  4. The Site 1070 m depth Absorption length: 20-30 m Scattering length: 30-70 m Ice as a natural deployment platform 51 d 45’’ 59’ N 104 d 25’ 09’’ E Shore station 4000 m 1366 m

  5. Ice as a natural deployment platform • Ice stable for 6-8 weeks/year: • Maintenance & upgrades • Test & installation of new equipment

  6. Baikal Baikal Baikal - Optical Properties Scatt. Length (geom) ~ 30-50 m cos ~ 0.85-0.9 Abs. Length: 22 ± 2 m Open configuration of the Telescope and good water parameters of Baikal water allow to observe big water volume much more than geometrical boundaries

  7. Baikal-NEMO CampaignMarch, 2001 • Example of interaction between ANTARES,NEMO   Baikal •  Verification of Lake Baikal Attenuation / Absorb. / Scatt. results • Cross-Calibration: AC9 (Antares/Nemo) vs.Burhan ASP15 see: NIM A498 (2003)

  8. Project Milestones 1991 Project NT200 approved 1993 NT36 36 OM at 3 strings The first underwater array operates First ’s and ’s in Neutrino Telescope 1996 NT96 96 OM at 4strings 1998: NT200 192 OM at 8 strings 1 Mton at 1 PeV 2005: NT200+ 228 OM at 8 + 3 strings 10 Mton at 10 PeV

  9. Quasar PMT: d = 37cm -8 strings: 72m height - 192 optical modules  96 measuring channels  T, Q measure *Timing ~ 1 nsec *Dyn. Range ~ 1000 pe Effective area: 1 TeV ~2000 m² Eff. shower volume: 10TeV ~0.2Mt Height x  = 70m x 40m, Vgeo=105m3= 0.1Mton

  10. Selected ResultsNT200 Low energy phenomena (muons) -Atmospheric neutrinos - WIMP neutrinos High energy phenomena (cascades) - Diffuse neutrino flux - Neutrinos from GRB - Prompt muons and neutrinos - Exotic HE muons Search for exotic particles - Magnetic monopoles

  11. Atmospheric Neutrinos 372 Neutrinos in 1038 Days (1998-2003) Important calibration tool ETHR 15-20 GeV Skyplot (equatorial coordinates) of neutrino events

  12. WIMP Search   +  b + b Search of nearly vertically upward going muons , exceeding the flux of atmospheric neutrinos Angular distribution of selected neutrino candidates as well as background expectation C +  +  Limits on the excess muon flux from the centre of the Earth as a function of WIMP mass

  13. Search for High Energy Cascades NT-200  NT-200 large effective volume Look for upward moving light fronts. Signal: isolated cascades from neutrino interactions Background : Bremsshowers from h.e. downward muons Final rejection of background by „energy cut“ (Nhit) • Physics topics: • HE cascades from • e  - NC/CC • * Diffuse astroph.flux • * GRB correlated flux • HE atmospheric muons • * Prompt  • * Exotic   („BG“) NT-200 is used to watch the volume below for cascades.

  14. Diffuse Neutrino Flux NT200 (1038 days) DIFFUSE NEUTRINO FLUX (Ф ~ E-2, 10 TeV < E < 104 TeV) e    = 1  2  0 (AGN) e    = 1  1  1 (Earth) g=1.5 2 2.5 Ф(ne+n+nt)E2<8.1 ·10-7GeV cm-2 s-1 sr-1 W-RESONANCE (e) ( E = 6.3 PeV, 5.3 ·10-31 cm2 ) Фe < 3.3 · 10-20 (cm2 · s · sr · GeV )-1 matm ~ tmin > -10ns Nhit > 15 ch. Hit channel multiplicity (experiment and background expectation) Shape of signal in Nhit distribution for Fn = AE-g (g=1.5, 2.0, 2.5).

  15. Diffuse Flux Limits + Models Experimental limits +bounds/ predictions Models already ruled out by the experiments SS - Stecker, Salamon96 (Quasar) SeSi - Semikoz, Sigl (Models/Expts. are rescaled for 3 flavours)

  16. NT-200 140 m 100m New configuration NT200+ 36 additional PMTs on 3 far ‘strings‘  4 times better sensitivity  Improve cascade reconstruction Vgeom ~ 4 ·106m3 Eff. shower volume: 104TeV ~ 10 Mton Expected -sensitivity (3 yrs NT200+) : E2 ФV< 0.9 · 10-7GeV cm-2 s-1 sr-1 NT200+ as test facility for Gton scale detector 1. Optical module 2. Calibration system 3. New electronics 4. Data acquisition system 5. Time synchronization 6. Cable communications

  17. NT200+ commisioned April 2005 1. 3 outer strings were instaled 2. New DAQ – final modernization - 2 Underwater PC with Flex DSL modem (1 Mbod), Underwater Ethernet - Synchronization system * time synchronization NT200 <-> outer strings * event clusterisation 3. New Software DOS -> Linux, Remote control 4. New 2 cables to shore (2x4 km) 5. Calibration - New bright Laser

  18. DAQ and control system of NT200+ Two subsystems: NT200 and NT+ Two-level time measurement and data acquisition systems: Low level: - Strings: PMT time and amplitude measurements; - DEM: trigger and event clusterisation systems - SEM: slow control DAQ Center - 2 underwater PC connected to shore; - CEM: trigger time measurement

  19. Underwater PCs PC104: Advantech-PCM9340 DSL-M: DSL-modem FlexDSL-PAM-SAN with hub and router, 2 Mbit/s. SwRSTP: a managed Ethernet switch RS2-4R CSrv: WUT-58211, for PC-terminal emulation Mc: two media-converters for coaxial connection D-Mod, C-Mod: experiment data and control modems

  20. X3 100m 100m 100m X1 X2 New Laser Laser intensity : cascade energy: (1012 – 5 1013 ) g : (10 – 500) PeV RMS of arrival time distribution: ~ 2 ns  Laser is visible >200m with high Ampl. (NT and ext.strings)

  21. NT200+ time resolution Dt = t1+ t12 – t2 st1, st2 - PMT jitter and light scattering s(t12)  2 ns - electronics jitter Light scattering - scattering length 30 m - distance to Laser ~200 m 5 series of Laser pulses Jitter of electonics ~2 ns - synchro cable length 1.2 km - TDC bin 2 ns t12 t2 The amplitude dependence of relative time jitter measured for several pairs of channels of NT200 and external string. Red line is result of calculations t1

  22. NT200+ efficiency of cascade reconstruction Laser coordinates reconstruction NT200 Reconstructed vs. simulated coordinates of cascades in NT200+ (blue) and NT200 (red) 3 extern. str. NT200+ Dr < 1 m

  23. NT200+ as a subunit of a Gton scale detector For High Energy Cascades: A single string replacing the NT200 central core reduces Veff less than x3 for E>100TeV.  12 OMs strings as a subunit for a Gton scale detector = ok. Effective volume with

  24. A future Gigaton (km3) Detector in Lake Baikal. Sparse instrumentation: 91 strings with 12/16 OM = 1308 OMs (NT200 = 192 OMs)  effective volume for 100 TeV cascades ~ 0.5 -1.0 km³  muon threshold between 10 and 100 TeV

  25. Gton detector at Baikal lake R&D on the basis of NT-200+ configuration 1. Optical module: PMT selection 2. Detector configuration: PMT location, string configuration, distances, … 3. Electronics: flash ADC, trigger conditions, … 4. Communications: optical cables, connectors, … 5. Data acquisition system, time synchronization

  26. CONCLUSION 1. BAIKAL lake experiment running since 12 years - Diffuse Neutrino flux limit - Limit on an excess flux due to WIMP annihilation in the Earth - Limit on the flux of fast magnetic monopoles 2. NEW configuration NT200+ start of operation April 2005 - NT200+ is tailored for diffuse cosmic neutrinos Veff ~ 10 Mton at 10PeV Expected -sensitivity (3 yrs NT200+) :E2 Фv < 10-7 GeV cm-2 s-1 sr-1 - NT200+ gives good possibilities to optimise the structure and to investigate the basic elements of future Gton scale detector 3. R&D Gigaton Volume Detector (km3) at Baikal lake was started

  27. Relativistic magnetic Monopole Cherenkov-Light n2·(g/e)2 n = 1.33 (g/e) = 137/ 2 8300 Flux upper limit (cm-2 s-1 sr-1)

  28. NT200+ Start of operation April 2005 • 13 Apr - 23 May 2005 • Exposition time:640hours • Events number:7.6 104 • - More than 1 outer string: 20 events Examples of events

  29. NT200+ Start of operation April 2005 • 13 Apr - 23 May 2005 • Exposition time:640hours • Events number:7.6 104 • - More than 1 outer string: 20 events Examples of events

  30. New Laser: Design • Isotropizer: - Glass bulb filled with “MicroGlassSpheres” (S32 from 3M; 20-70um dia.) mixed with OpticalGel  A “LaserBall” similar to the SNO calibration device. - Total loss is low: 12% - 25% only ! calibrated with “Ulbricht Sphere” (1.5m diam.) • Absolute Laser–Calibration (with commercial Laser-PowerMeter) to optimize yield also at the lake (monitor laser vs. years) • Expect >10^12 photons/pulse

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