1. The BAIKAL Neutrino Telescope: from NT200 to NT200+ 29 th ICRC Pune, India, 5.8.2005 Ralf Wischnewski DESY-Zeuthen

2. R.Wischnewski 29thICRC, Pune, India, 2005 2 Outline: -Motivation + Detection Principle -Design: NT200 and NT200+ - Physics Results (selected) : NT200 1998-2003 -Perspective + Summary

3. R.Wischnewski 29thICRC, Pune, India, 2005 3 High Energy -Astronomy --> Catch first astrophyical HE ’ s  Cosmic ray acceleration sites  New observational window to Universe (new objects ?) Dark Matter (neutralino annihilation in Earth/Sun/Gal.C.) Prompt lepton production in atmosphere ( + µ ; cross sections, …) Exotic particles: Magnetic Monopoles (relativistic or slow [10 -5 - 10 -3 ]) … … HE atmospheric muons (exotic component ?), ………… Neutrino Telescopes: Physics Motivation Astro - Astro - - Particle Physics

4. R.Wischnewski 29thICRC, Pune, India, 2005 4 Physics Background: atmospheric neutrinos A. Point sources “Find the sources on the sky” + clean signal - needs strong enough single sources B. Anomalies in atmospheric -energy spectrum + all weak point sources should add up + model predictions ~ exp.sensitivities - systematics Astrophysical ’s: Two detection methods Skyplot with Hot spot(s) (galactic coordinates) Charged Current (CC)  N  µ X Electron / hadron cascades from CC + NC e /  / (  ) log [ E 2 · Flux(E ) 3 96 AGN atmospheric log (E /GeV) Point source search Search for a diffuse flux

5. R.Wischnewski 29thICRC, Pune, India, 2005 5 A Amanda/IceCube Baikal N N Baikal Telescope: Russia – Germany - Institute of Nuclear Research, Moscow - Moscow State University - DESY Zeuthen - Irkutsk State University - Nishni Novgorod State Technical University - State Marine Technical University, St.Petersburg - Kurchatov Institute, Moscow - JINR, Dubna ~45 authors

6. The Site 4 cables x 4km to shore. 1100m depth 3600 m 1366 m NT200+

7. R.Wischnewski 29thICRC, Pune, India, 2005 7 NT200+ = NT200 + 3 long outer strings - Height = 210m - = 200m -  = 200m - Volume ~ 5 Mton

8. R.Wischnewski 29thICRC, Pune, India, 2005 8 The NT-200 Telescope -8 strings: 72m height - 192 optical modules = 96 pairs (coincidence) - measure T, Charge - σ T ~ 1 ns - dyn. range ~ 1000 p.e. Effective area: 1 TeV ~2000 m² Eff. shower volume: 10TeV ~0.2Mt Quasar PMT: d = 37cm Height x  = 70m x 40m, V geo =10 5 m 3 = 0.1Mton

9. R.Wischnewski 29thICRC, Pune, India, 2005 9 NT200+ commissioned April 9, 2005 Upgrade 2003-2005: - 3 outer strings were installed - DAQ – modernization - 2 Underwater PC with Flex DSL modem (1 Mbps), full multiplexing, Underwater Ethernet - Synchronization unit * time synchronization (~ ns) NT200 outer strings * event building - Transition to Linux, RemoteCntrl. - Calibration - New bright Laser - 2 new cables to shore (2x4 km)

10. R.Wischnewski 29thICRC, Pune, India, 2005 10 ExtStr 1 ExtStr 3 ExtStr 2 NT200 Center+Outer New ShoreCable 100 m March, 2005, 4km off-shore: NT200+ deployment from ice. Ice – A perfect natural deployment platform Ice is stable for 6-8 winter-weeks/year: –Upgrades & maintenance –Test & installation of new equipment –Operation of surface detectors (EAS, acoustics,… ) –Electrical winches used for deployment operations

11. R.Wischnewski 29thICRC, Pune, India, 2005 11 NT200+ Time Synchronization (new laser) >10 12 photons/pulse Laser: (400kW / 1 ns) Time calibration + Imitation of 20TeV-10PeV cascades, >10^12 photons/pulse w/ diffusor, >10^12 photons/pulse w/ diffusor, up to ~200m for full NT200+ up to ~200m for full NT200+ Time differences NT200 - outer string: Jitter is < 3ns rms for NT+/NT200.

12. R.Wischnewski 29thICRC, Pune, India, 2005 12 NT200 - Selected Results - - Low energy phenomena - Atmospheric neutrinos - WIMP Neutrinos - -High energy phenomena Diffuse neutrino flux - Diffuse neutrino flux - Neutrinos from GRB - Prompt muons and neutrinos - Exotic HE muons - - Search for exotic particles - Relativistic Magnetic monopoles Data sample - 1998-2002: 1038 days (Apr.98-Feb.03) - 1998-1999: 502 livetime days earlier results Poster HE2.3

13. R.Wischnewski 29thICRC, Pune, India, 2005 13 Relativistic Monople Flux limit Fig 4.9()% C.L. upper limit on the flux of fast monopole and experimental limits from [4,6,7] Baikal Search: 1998-2003 See Poster Session2 HE 2.3

14. R.Wischnewski 29thICRC, Pune, India, 2005 14 Atmospheric Muon-Neutrinos - With looser cuts, 1998-2002: 372 events.  A higher statistics neutrino sample for Point-Source Search. - MC: 385 ev. Expected (15%BG). - No indication for Point Sources found. Skyplot (galactic coordinates) E_thr ~ 15GeV

15. Search for High Energy Cascades NT-200 is used to watch the volume below for cascades. 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“ (N hit )  („BG“) NT-200 large effective volume e cascades Allowed by excellent scatt  scatt =30-50m Radius, m

16. Physics topics: - - HE cascades from e   - NC/CC   Diffuse astroph.flux   GRB correlated flux - - HE atmospheric muons ( the „BG“ to ‘s )   Prompt    Exotic  -... Search for High Energy Cascades NT-200 is used to watch the volume below for cascades.  („BG“) NT-200 large effective volume

17. Hard signal spectra would pile up in the “energy parameter” N hit = Number of Channels hit Shape of signal in Nhit distribution for    A E -  (  Selecting HE Cascades  atm 2.5  1.5 2 cut Data + MC Showers along  

18. Diffuse Flux e, ,  Limit 90% C.L. Limit via W-RESONANCE production ( E = 6.3 PeV,  5.3 ·10 -31 cm 2 ) Ф e < 3.3 · 10 -20 (cm 2 · s · sr · GeV ) -1 (Baikal 2005) Ф e < 5.0 · 10 -20 (cm 2 · s · sr · GeV ) -1 (AMANDA 2004) No events observed (+ 24% system. err.)  2.5 evt exp. The 90% C.L. “all flavour” limit (1038 days) for a  =2 spectrum Ф ~ E -2 (20 TeV < E < 50 PeV), and assuming e :  :  = 1  1  1 at Earth ( 1  2  0 at source ) E 2 Ф < 8.1 ·10 -7 GeV cm -2 s -1 sr -1 (Baikal 2005) E 2 Ф < 8.6 ·10 -7 GeV cm -2 s -1 sr -1 (Cascades AMANDA-II, 2004) V geo (NT-200) AMANDA II V eff > 1 Mton at 1 PeV Effective Volume vs. Energy

19. R.Wischnewski 29thICRC, Pune, India, 2005 19 Experimental limits + bounds/ predictions Diffuse Flux Limits + Models Models already ruled out by the experiments: SDSS - Stecker et al.92 SS - Stecker, Salamon96 (Quasar) SP - Szabo, Protheroe92 (Models/Expts. are rescaled for 3 flavours)

20. NT200 + NT200+ as a subunit of a Gton scale detector ? For High Energy Cascades: A single small string replacing the NT-200 central core reduces V eff less than x3 for E>100TeV.  Short strings as a subunit for a Gton scale detector = ok. 140 m Effective volume with

21. R.Wischnewski 29thICRC, Pune, India, 2005 21 NT200 + Much improved cascade coordinates (+ energy ) reconstruction. Expected e - sensitivity (3 yrs NT200+) : E 2 Ф < 0.9 · 10 -7 GeV cm -2 s -1 sr -1  3-4 fold rise in sensitivity for “classical HE cuts” (vertex + energy reco will improve !)

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

23. R.Wischnewski 29thICRC, Pune, India, 2005 23 1. The Baikal Telescope NT200 is in operation since 1998. 2. NT200 is focusing on search for HE-diffuse neutrinos: A “Mton-detector” with only 100kt enclosed volume. - Diffuse flux limits for 4 years (98-03) are attacking AGN-models. At same level as Amanda (1yr) & complementary (method, North,…) - Other new results from NT200 (not presented here): Fast Magnetic Monopoles, HE atm.  (prompt; exotic), WIMPs, GRBs 3. Upgrade to NT200+ in April, 2005: - NT200+ is tailored to diffuse cosmic neutrinos - 5 Mton equipped volume; V_eff > 10 Mton at 10 PeV  sensitivity improvement by 3…4 x 4. Ideas for future: Gigaton Volume Detector (km3-size array) 5. Baikal is complementary to Amanda: location, water (low scatt), reconstruction Summary

24. R.Wischnewski 29thICRC, Pune, India, 2005 24 BAIKAL NT200+ will for a while be the largest Northern hemisphere HE-nu Cherenkov Telescope. BAIKAL NT200+ will for a while be the largest Northern hemisphere HE-nu Cherenkov Telescope.

25. R.Wischnewski 29thICRC, Pune, India, 2005 25 Reserve… Fig 4.9()% C.L. upper limit on the flux of fast monopole and experimental limits from [4,6,7]