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The BAIKAL Neutrino Telescope: Results and Plans

The BAIKAL Neutrino Telescope: Results and Plans. 19 th ERCS, Florence, Italy,September 3 rd , 2004. Ralf Wischnewski DESY-Zeuthen. O(km) long muon tracks. Electromagnetic & hadronic cascades.  5- 15 m. ~ 5 m. CC  e   + Neutral Current. Charged Current (CC)  .

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The BAIKAL Neutrino Telescope: Results and Plans

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  1. The BAIKAL Neutrino Telescope: Results and Plans 19th ERCS, Florence, Italy,September 3rd, 2004 Ralf WischnewskiDESY-Zeuthen

  2. O(km) long muon tracks Electromagnetic & hadronic cascades  5-15 m ~ 5 m CCe + Neutral Current Charged Current (CC)  - Good directionality by Cherenkov timing - Poor energy resolution direction determination by Cherenkov light timing - Good energy resolution - Bad pointing HE Neutrino Detection: Muons and “Cascades” R.Wischnewski ECRS2004

  3. The case for “All flavor” detection (1)  - Oscillation transfers the canonical e::=1:2:0 at source(e.g. from +- decay) to e::=1: 1: 1 at earth  50 % of signal  are ‘lost’ !  Catch all flavours (2) Earth is opaque for ‘upward’  at E >> PeV. But: regenerate via -decay and pile up at transparency E-threshold, i.e. do not ‘disappear’ .

  4. Sky coverage in Gal.Coordinates Lake Baikal Lake Baikal (and Mediterranean...) Visibility: below local horizon - white = 100% visibility - black = „blind region“ South Pole South Pole (AMANDA) = galactic center The case for >1 Uw/Ice - Telescopes • Complete sky coverage

  5. Lake Baikal South Pole The case for >1 Uw/Ice - Telescopes • Complete sky coverage (2) Complementarity of detectors • Optical medium: scattering vs. no-scatt. • Effective volume: contained vs. external • Pattern recognition & filtering criteria

  6. Outline • NT-200 design + history • Results: - Atm. Neutrinos, WIMPs, Monoples, - Cascades  AP neutrinos, muons • Physics upgrade to NT-200+ to be finished in April 2005 R.Wischnewski ECRS2004

  7. Collaboration 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 R.Wischnewski ECRS2004

  8. The Site 3600 m • 4 cables x 4km to shore. • 1070m depth 1366 m NT-200

  9. Winches used for deployment • operations  Ice as a natural deployment platform • Ice stable for 6-8 weeks/year: • Maintenance & upgrades • Test & installation of new equipment • Operation of surface detectors (EAS, acoustics,… )

  10. The Ice Camp (4km offshore) R.Wischnewski ECRS2004

  11. -8 strings: 72m height • - 192 optical modules • pairwise coincidence •  96 space points • calibration with N-lasers • timing ~ 1 nsec • Dyn. Range ~ 1000 pe Effective area: 1 TeV ~2000 m² Eff. shower volume: 10TeV ~0.2Mt Quasar PMT: d = 37cm Height x  = 70m x 40m, Vgeo=105m3= 0.1Mton The NT-200 Telescope R.Wischnewski ECRS2004

  12. Optical Module – Pair (Coincidence) R.Wischnewski ECRS2004

  13. 8 Strings on a Heptagon frame d=40m 21.5 m long arms allow for separate String manipulation N.B.: Flexiblity - additional (external) strings can be deployed independently (and re-positioned) at any place. R.Wischnewski ECRS2004

  14. ...and retrieval one year later. Final deployment of the Heptagon … NT-36, April 1993 R.Wischnewski ECRS2004

  15. Absorption cross section, m-1 Scattering cross section, m-1 Baikal Baikal , nm , nm Optical Properties FreshWater  no K40 BG In-situ measurements over many years Scatt. Length (geom) ~ 30-50 m cos ~ 0.85-0.9 Abs. Length: 22 ± 2 m 2001: Cross calibration with NEMO/ANTARES Latt-device

  16. One of the first neutrino events recorded with the 1996 four-string version NT-96 of the Telescope • 1998 – NT-200 commissioned 06.04.98(192 PMTs at 8 strings) • Start full Physics program • since 1998: Routine operation 4-string stage (1996) Baikal - History • Since 1980 – Site tests and early R&D started • 1989/90 - Proposal NT-200, start construction • 1993 – NT-36started 13.4.93 (36 PMTs at 3 strings) • The First Underwater Array ever built • 3-dimensional Muon reconstruction • Verify BG-suppression & check MC/Water/.. • First 2 Neutrino Candidates R.Wischnewski ECRS2004

  17. Ai, ti atm. m Time difference (dt = t52-t53) Amplitude (Chan 12) Reconstructed m’s : Cos(zenith) distribution vs. Corsika dt, ns 1. 0.2 cos (  ) Photoelectrons Atmospheric muons: Calibration Beam R.Wischnewski ECRS2004

  18. Selected Results • Low energy phenomena • - Atmospheric neutrinos • - Neutrino from WIMP annihilation • Search for exotic particles • - Magnetic monopoles • High energy phenomena • - Diffuse neutrino flux • - Neutrinos from GRB • - Prompt muons and neutrinos R.Wischnewski ECRS2004

  19. Data samples NT-200 - 1998-1999: 502 livetime days (Apr.98-Feb.00) - 1998-2000: 780 livetime days (Apr.98-Feb.01) (this work ) - 2001-2002: in progress - earlier results: for prototype NT-96, ... R.Wischnewski ECRS2004

  20.  ~ 3° Skyplot (galactic coordinates) cos (  ) Atmospheric Muon-Neutrinos • 3-dimensional track reconstruction • high BG suppression •  84 events in 1998+99 Soon to come: - a high statistics neutrino sample („looser criteria“) for Point-Source Search. - Muon-Neutrino GRB analysis Thresh.~ 15 GeV BG dominated bin R.Wischnewski ECRS2004

  21. Detection area, m2  +   b + b C +  +  cos (  )  W + + W - WIMP Neutrinos from the Center of the Earth • Tailored Vertical Track Reconstruction (single string) • Effective Area > 103 m2 (after all cuts)

  22. no osc. osc. WIMP Search Limit on excess neutrino induced upwardmuon flux 90% c.l. limits from the Earth ( 502 days NT-200 livetime, E> 10 GeV ) 502 days livetime NT-200 (98+99) MC: Bartol-96 24 evts - experiment 36.6 evts - prediction w/o oscillations 29.7 evts - prediction w/ oscillations

  23. Monopole limit (90% C.L.) 780 livedays Parker Nhit distribution: MC  data Nhit Search for fast Monopoles (b > 0.8) Ng monop(l) = n2 (g/e)2 Ngm(l) = 8300 Ngm(l) g = 137/2, n = 1.33 Bright light source: 8300 x muon • Monopole selection criteria: • hit channel multiplicity: Nhit> 35ch, • upward track:S(zi-z)(ti-t)/(stsz) > 0.45 , q > 100o • Background : atmospheric muons R.Wischnewski ECRS2004

  24. Search for Slow Massive Monopoles(10-5 < b < 10-3) NT-200 – capable to detect massive bright objects (GUT-monopoles, nuclearites, Q-balls …): Monopole Trigger: Nlocal>4 within dt=500msec Selection: Nch>1 with Nlocal>14 scat=0.17s0 /b2, 10-5<b<10-3 M+p M+e+ (+p…),Ng~105 Magnetic monople Flux limit Magnetic monopole visibility boundaries R.Wischnewski ECRS2004

  25. NT-200 NT-200  necascades large effective volume Allowed by excellent scatt scatt=30-50m Radius, m Search for High Energy 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“ (Nhit) NT-200 is used to watch the volume below for cascades.  („BG“)

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

  27. g=1.5 2 Data + MC 2.5 matm cut Hard spectra pile up in the “energy parameter” N hit Fn = AE-g Shape of signal in Nhit distribution (g=1.5,2.0,2.5) Selecting HE Cascades Showers along

  28. AMANDA II Vgeo (NT-200) Diffuse Flux ne, nt, n Limit The 90% C.L. “all flavour” Limit from NT-200 (780 days) on the DIFFUSE NEUTRINO FLUX Assuming ne  n nt= 1  1  1 at Earth ( 1  2  0 at source) + for a =2 spectrum Ф~ E-2 (10 TeV < E < 104 TeV) E2 Фn< 1.0 ·10-6GeV cm-2 s-1 sr-1 (Baikal 2004) E2 Фn< 0.86 ·10-6GeV cm-2 s-1 sr-1(AMANDA-II 2004) Effective volume vs. E 90% C.L. Limit via W-RESONANCE production ( E = 6.3 PeV, s = 5.3 ·10-31 cm2 ) Фne < 4.2 · 10-20 (cm2 · s · sr ·GeV )-1 (Baikal 2004) Фne < 5.0 · 10-20 (cm2 · s · sr ·GeV )-1 (AMANDA 2004) Veff > 1 Mton at 1 PeV

  29. Experimental limits + theoretical predictions Diffuse Flux Limits + Models • Models already ruled out by the experiments • SDSS - Stecker et al.92 • SS - Stecker, Salamon96 • SP - Szabo, Protheroe92 • (Models/Exp. are rescaled for 3 flavours) Telescopes attack Models agressively.

  30. Search for ’s correlated with GRBs BATSE-GRBs vs. HE-Cascades event sample. GRB - Prospects: We expect better sensitivity for the muon event sample. Analysis in progress. April 1998 - February 2000: Ntot= 722 BATSE evts NT-200:CascadeCuts (Nhit>10 & tmin>-10 ns) & tBATSE-100 s < t < tBATSE+100 s prelim. prelim. Data consistent with expected at-BG  90% C.L. differential flux limits 1 PeV R.Wischnewski ECRS2004

  31. Neutrinos -nm, ne: cascades (CC, NC) AnE-2.6, E<Eb=3 105 GeV Fn= An Eb0.4 E -3,E>Eb=3 105 GeV Muons: cascades (e+e-, brem, ph.-nucl.) Fm=AmE-2.6 prelim. Prompt atmospheric ’s and muonsBG source for neutrino telescopes Production - decays of short-lived particles (L, D, …) Fm~ Fn - isotropic for E < 107 GeV Predictions: ZHV - E.Zas, F.Halzen, R.Vazquez-93 RVS - O.Ryazhskaya, L.Volkova, O.Saavedra-02 QGSM, RQPM - E.Bugaev et al.-89 TIG - M.Thunman, G.Ingelman, P.Gondolo-96 GGV - G.Gelmini, P.Gondolo, G.Varieschi-02 (hep-ph/0209111) Baikal R.Wischnewski ECRS2004

  32. Limits to HE Muon Flux • Any HE muon model spectrum can be tested by the selected HE Cascade event sample. • Example: • “Exotic Muons” as discussed in some talks at this meeting • (curve “a” and “b”). • a detailed limit calculation for these “predictions” is in progress. The limit for E-2 spectrum shows we have rejection model power. Flux prediction and flux limits

  33. NT-200 140 m 110100 1000PeV Aim: Improve sensitivity to cascades with sparse instrumentation. Upgrade to NT-200+ 41523 40Mton 36 additional PMTs on 3 far ‘strings‘  4 times better sensitivity !

  34. NT-200+ Much improved cascade coordinates (+ energy ) reconstruction

  35. NT-200 140 m NT-200+ NT - 200+ as subunit for a Gton scale detector For High Energy Cascades: A single small string replacing the NT-200 central core reduces Veff less than x3 for E>100TeV.  Short strings as a subunit for a Gton scale detector

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

  37. NT-200+ Status 2004: - Two outer strings are installed 2.3 104 common events taken during 364 h life time (0.017 Hz) - New cable to shore(4km underwater) - DAQ system redesigned - MBit-DSL shore connection: x100 bandwidth - Embedded Linux PC’s and Ethernet underwater (fast trigger Level 0 possible) - Remote Experiment Control from Moscow/... 2005: - NT-200+ will be completed

  38. NT-200+ DAQ-Upgrade, 3/2004 • Linux and Ethernet “go underwater” for the new Baikal-DAQ: • - 3 Baikal-spheres with first PCs ready for deployment (left) • - Mounting the central trigger/DAQ underwater system (right) R.Wischnewski ECRS2004

  39. Summary - The Baikal Telescope is successfully running since 10 years - strong in HE-diffuse search (cascades): “Mton-detector” - good GRB-sensitivity - relevant other results: Magnetic Monopoles, WIMPs, atm.  - complementary to AMANDA (sky, optical, pattern-reco, …) - aggressive upgrade to NT-200+ in 2005: improve the HE cascade sensitivity by 2 ...4 - also: ideas on a future Gigaton Volume Detector (km3) R.Wischnewski ECRS2004

  40. BAIKAL will for a few years remain the largest (and only) Northern hemisphere Underwater Cerenkov Telescope. Almost exactly like our HE-Gamma colleagues we eagerly wait for more sources to show up in our field of view … At least one per Telescope … R.Wischnewski ECRS2004

  41. R.Wischnewski ECRS2004

  42. Backup Slides ... R.Wischnewski ECRS2004

  43. WIMP Search Expectation for atmospheric neutrinos: Atm. neutrino induced muons (Eth~ 10 GeV) Atmosp. neutrinos (Bartol-96, SK-oscillation)

  44. High energy cascade selection: • Upward light from below : • tmin = min(ti - tj ), j > i (for all strings in event) • tmin> -10 ns • (2)High energy: • N hit > 15 ch. Nb. of hit channels Selecting HE Cascades tmin: data (Nhit>40 ch.) tmin:Data + MC (tmin>-10 ns)

  45. Event selection criteria • - experiment • - atm. muons background High energy cascades R.Wischnewski ECRS2004

  46. Backup slides R.Wischnewski ECRS2004

  47. see: NIM A498 (2003) 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 (Baikal)  Agreement ! R.Wischnewski ECRS2004

  48. Shore Station with OMs (April 1993) R.Wischnewski ECRS2004

  49. The end. R.Wischnewski ECRS2004

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