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The AMANDA-II Telescope - Status and First Results -

The AMANDA-II Telescope - Status and First Results -. Ralf Wischnewski / DESY-Zeuthen for the AMANDA Collaboration. TAUP2001, September 2001, LNGS/Italy. ralf.wischnewski @ desy.de. HE  ’ Telescopes …. HE  -Telescopes are still ”novel” instruments

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The AMANDA-II Telescope - Status and First Results -

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  1. The AMANDA-II Telescope- Status and First Results - Ralf Wischnewski / DESY-Zeuthen for the AMANDA Collaboration TAUP2001, September 2001, LNGS/Italy ralf.wischnewski@desy.de

  2. HE ’ Telescopes … • HE -Telescopes are still ”novel” instruments • proving sensitivity to their primary channels • nm  N   X • eN  e X  from Astrophysical Sources ( Point / Diffuse ) •  calibration possible only with atmospheric ‘s

  3. Outline • 1. AMANDA-II Detector • 2. Calibration of the AMANDA-B10 detector with • Atmospheric ‘s  Physics results from B10/1997, see A.Hallgren • 3. Performance & Sensitivity of AMANDA-II

  4. AMANDA-II Construction 1996 4 strings, coax transmission OMs total 86 OMs  AMANDA-B4 1997 +6 strings, twisted pair transmission OMs total 302OMs at 10 strings AMANDA-B10 1998 +3 strings, fiber transmission OMs total 424 OMs  AMANDA-B13 2000 +6 strings, fiber and digital transmission OMs total 677 OMs at 19 strings AMANDA-II 2003-2008~80 strings with 60 OMs each, total 5000 OMs  ICECUBE

  5. AMANDA-II (February 2000) • 677 PMTs • 19 Strings • d = 200 m • h  500 m •  Vgeo1.6 107m3 • Trigger: • Majority • >23 OM in <2.5 s • String Trigger

  6. Atmospheric Muon Background -Signature:Upgoing muon  from CR Background: Misreconstructed atmospheric muons Noise/Signal = /(atm) =105…6  from atm. Zenith of ‘s triggering AMANDA

  7. Maximum Likelihood Reconstruction Variation of track parameters until the spectrum of arrival times has highest Likelihood. Scattering results in a distance dependent time-delay relative to the Cherenkov cone.

  8. Atmospheric -Analysis • Two (largely) independent analyses were done for the • 1997 data set of Amanda-B10 with respect to • - methodical aspects (Cut definitions, minim.functional) • - data cleaning (electronic noise ...) • Used same signal & atmospheric muon Background MC (BG-MC) and track model (ice optics and single muon)

  9. Analysis A: Overview • Conventional Likelihood description (no zenith weight) • Multi-photon Likelihood and hit-probabilities • Background rejected by specific cuts: • e.g. cascade fit for muon bremsstrahlung. • Reject instrumental BG by hit-topology • Cuts developed with emphasis on BG-MonteCarlo • Deterministic method to define a small set of final Cutparameters and their values (  CutEval)

  10. Neutrino Analysis Chain (A) Nevents bg sig S/N Pre-processing :1•109 0.95 0.95 1 : 2•105 Hit cleaning, Calibration ... Level 1:5•107 5•10-2 0.37 1 : 3•104 Fast track approximation (line fit) Simple up/down cut Level 2:4• 105 4•10-4 0.15 1 : 5•102 Time-likelihood reconstruction. Simple cuts (zenith,L,Ndir) Level 3:1• 104 1•10-5 0.07 1 : 30 First cut optimization. Full likelihood reconstruction. Level 4: 223 2•10-8 0.04 10 : 1 Final Neutrino Cuts (CutEval)

  11. Analysis A: Neutrino Cuts & Sample Size Define „Sample Quality“: Q = -log (NBG /NTL) Sample Quality, Q Find (minimum) set of Cut-Variables, which optimize the signal to background efficiency Data BG-MC Sig-MC

  12. Neutrino Events – Statistics 130.1 days live time

  13. Systematic Uncertainties - 5 % Time Geometry Amplitude OM sensitivity -5 % Calibration < 5 % -20 % Bulk Ice Vertical structures Hole Ice ± 10 % Optical properties ± 10 % -50 % -prop./light yield -flux -oscillations ± 20 % Physics ± 30 % -20 %

  14.  - Luminosity versus day in 1997 Neutrino candidates Nb. of trigger (Mill.) Number of Neutrino events and total number of triggers in 1997 (analysis A). Total live time was 130.1 days.

  15. Zenith angle distribution Events /130d /0.1 Cos(zenith) Analysis A

  16. Energy distribution E  ~ .07–3.4 TeV (MC) 10 GeV 100 GeV 1000 GeV

  17. Celestial distribution Combined sample 325 events 130.1 days live-time Noclustering Pointing:3ª - 4ª

  18. Oscillations:Zenith dependence Events /130d /0.05 Ratio Osci/No oscci (MC) Cos(zenith) Cos(zenith)

  19. Oscillations: Neutrino Energy (MC)

  20. Summary: B-10 atmosph. ’s • The AMANDA-B data from 1997 (130.1 days live time) have been analysed for neutrinoinducedevents • 2 independent analyses find a total of 325neutrinoevents with less than 10% background contamination • Results are consistentwith the MC expectation for background (atmospheric muons) and signal (atmospheric neutrinos) within (still relatively large) systematic uncertainties • Improvement expected from • - better local ice-properties & OM sensitivity calibration • - improved MC light tracing & HE muon light yield • AMANDA has reached „design luminosity“ !

  21. Amanda-II • Larger effective area by 9 more strings (>double OMs) • New technologies • - improved timing • - MultiHit resolution (muon bundles & HE events) • - reduced electronic noise • - Upgrade: full waveform sampling (FADCs) in 2002 • Triggering • - HE events by majority trigger • - E<100 GeV by string trigger • - EAS-Array (SPASE) as efficient veto for UHE events • Improved angular sensitivity range; resolution ~ 2 degrees

  22. Amanda-II • Amanda-II analysis for 2000 started in spring 2001 (1.2 TB Data back from Spole) • Neutrino Analysis profits substantially from Amanda-B10 • analysis. • Tuning to new geometry and hardware is under way. • Minimum bias and low neutrino-cut level data look ok vs. MC. • MC-results given below for „final AM-II neutrino cuts“ (Aeff, ,...) are still preliminary.

  23. Amanda-II: Detector response Number of hit Optical Modules All Strings (1-19) Inner Strings (1-10) Outer Strings (11-19) Data - dots MC - line

  24. Amanda-II: Detector response Minimum bias Zenith & Azimuth acceptance

  25. Event Rates: nm andne Trigger Level Atmospheric nm - 11000 (CC) - 130 (NC) ne - 160 (CC) - 9 (NC) AGN (E-2 10-6 GeVcm- 2s- 1sr-1 ) nm - 853 (CC) ne - 103 (CC) ATM nm AGN ne

  26. Atmospheric nmMC: Energy response Trigger Level Aeff(E) much improved compared to AMANDA-B10 After BG rejection

  27. Atmosph. nmMC: Angular Sensitivity Trigger Level ~200 atm n per angular bin & livetime-year After BG rejection Nearly uniform angular sensitivity to horizon up horizon

  28. AMANDA-II:a horizontal nm event ( preliminary Am-II neutrino- cuts )

  29. Am-II: Effective Area vs zenith Aeff depends sensitively on the physics objective! Point source sensitivity is uniform to near horizon

  30. Amanda-II - Effective Volume • Veff (nm) is • 0.3-0.5 km3 • Rm> 10 km (for Point Source Cuts)

  31. Convolved energy resolution New techniques Diffuse Flux nm AGN Core Anticipated sensitivity

  32. Upper Bounds on Diffuse Flux Baikal NT-200 Anticipated sensitivity AMANDA-II

  33. Point Sources Atmospheric Fn + energy resolution

  34. Point Sources Focus on Mk501 as example

  35. UHE events • Earth shadowing of n‘s becomes relevant for En > 1 PeV • Horizontal and „downgoing“ events dominate • New search strategies under development • - Total energy cuts & Energy flow • vs. track reconstruction • - EAS-Veto by surface Array SPASE

  36. Downgoing n -induced MuonFlux

  37. Angular distribution Most events are horizontal. EeV sources cut off very quickly below horizon. Direction provides additional BG reject. Up Down

  38. Summary • AMANDA-B10 • Final Analysis (1997) yields 325 HE neutrino events The first high statistics n-event sample for an UWater/Uice Telescope Proof of principle of operation in Antarctic scattering ice. • AMANDA-II • >105 m2 Trigger Area - the Largest Muon and Neutrino • Telescope ever built. • Improved performance compared to B10-Telescope • Horizontal Angular acceptance • Event rates of 4-5 atm. n‘s per livetime day, • 800-1000 n‘s for year-2000.

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