The BAIKAL Neutrino Telescope: from NT200 to NT th ICRC Pune, India, Ralf Wischnewski DESY-Zeuthen

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

R.Wischnewski 29thICRC, Pune, India, 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 [ ]) … … HE atmospheric muons (exotic component ?), ………… Neutrino Telescopes: Physics Motivation Astro - Astro - - Particle Physics

R.Wischnewski 29thICRC, Pune, India, 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

R.Wischnewski 29thICRC, Pune, India, 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

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

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

R.Wischnewski 29thICRC, Pune, India, The NT-200 Telescope -8 strings: 72m height 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

R.Wischnewski 29thICRC, Pune, India, NT200+ commissioned April 9, 2005 Upgrade : - 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)

R.Wischnewski 29thICRC, Pune, India, 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

R.Wischnewski 29thICRC, Pune, India, 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.

R.Wischnewski 29thICRC, Pune, India, 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 : 1038 days (Apr.98-Feb.03) : 502 livetime days earlier results Poster HE2.3

R.Wischnewski 29thICRC, Pune, India, 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: See Poster Session2 HE 2.3

R.Wischnewski 29thICRC, Pune, India, Atmospheric Muon-Neutrinos - With looser cuts, : 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

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

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

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  cut Data + MC Showers along  

Diffuse Flux e, ,  Limit 90% C.L. Limit via W-RESONANCE production ( E = 6.3 PeV,  5.3 · cm 2 ) Ф e < 3.3 · (cm 2 · s · sr · GeV ) -1 (Baikal 2005) Ф e < 5.0 · (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

R.Wischnewski 29thICRC, Pune, India, 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)

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

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

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

R.Wischnewski 29thICRC, Pune, India, The Baikal Telescope NT200 is in operation since 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

R.Wischnewski 29thICRC, Pune, India, 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.

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