A M A N DA Antarctic Muon And Neutrino Detector Array Status and Results

Transcription

1 A M A N DA Antarctic Muon And Neutrino Detector Array Status and Results ( Peter Steffen DESY Zeuthen, Germany TAUP 2003

2 The AMANDA Collaboration ª 150 members New Zealand Japan Antarctica Europe (10+1) Venezuela (1) USA (7+3) Bartol Research Institute UC Berkeley UC Iivine Pennsylvania State UW Madison UW River Falls LBL Berkeley U. Simón Bolivar, Caracas VUB, Brussel ULB-IHEE, Bruxelles U. de Mons-Hainaut Imperial College, London DESY, Zeuthen Mainz Universität Wuppertal Universität Stockholm Universitet Uppsala Universitet Kalmar Universitet South Pole Station + associated IceCube institutes in USA, Europe, Japan, New Zealand

3 Outline - introduction - atmospheric muons - atmospheric neutrinos - search for extraterrestrial neutrinos: Æ diffuse flux in the range TeV PeV Æ diffuse flux in the range PeV EeV Æ search for point sources - search for neutrinos from WIMP annihilation - other results: search for magnetic monopoles, SN monitoring Æ cosmic ray composition - summary and outlook - GRB: Kyler Kuehn - IceCube: Shigeru Yoshida

4 Physics motivation - high energy neutrino astronomy origin and acceleration of cosmic rays - indirect search for dark matter (e.g. neutralino annihilation) - search for magnetic monopoles and other exotic objects - supernova monitoring - composition of primary cosmic rays

5 Neutrino source candidates Supernova remnant Microquasar Active Galaxy ª 1 LY ª 10 6 LY Crab nebula galactic Black hole with ª mass of sun Black hole with 10 8 x mass of sun extra-galactic

6 The Site South Pole AMANDA 2km deep Amundsen-Scott Station

7 AMANDA-II and SPASE inner 10 strings: Amanda-B10 South Pole Air Shower Experiment 19 strings 677 PMTs OM:optical module : deployment and first data taking AMANDA II

8 Detection of neutrinos n m (n e ) Cosmic rays n m (n e ) atmospheric muons TeV: use upward going muons PeV: use horizontal events EeV: use events from above

9 Detection of n m - Cherenkov light emision along the track - track position from time signals of PMTs ª 15 m

10 Detector capabilities muons: directional error: log E resolution: coverage: 2p 2-5m 2 n m effective area (schematic): n-interaction in earth, cuts cascades : (e ±, t ±, neutral current) zenith error: log E resolution: coverage: 4p 3 cm 2 µ E n GeV 100 TeV 100 PeV

11 Two events: muon and cascade 200 TeV n e candidate

12 Atmospheric muons in AMANDA-II Atmospheric muons and neutrinos: AMANDA s test beams data 30% higher than MC (QGSJET) Â normalize to most vertical bin PRELIMINARY Systematic errors: 10% ice parameters: scattering ( 400nm) absorption 400nm) 20% optical module sensitivity 10% refreezing of ice in hole threshold ~ 40 GeV (zenith averaged)

13 Atmospheric n's in AMANDA-II neural network energy reconstruction regularized unfolding spectrum up to 100 TeV compatible with Frejus data PRELIMINARY 1 TeV In future, spectrum will be used to study excess due to cosmic n s

14 Search for extraterrestrial neutrinos - background: - fake-reconstructed atmospheric muons, - neutrinos from atmospheric air showers (steeply falling energy spectrum, diffuse in direction) - signal: - excess of diffuse flux at high energy, - accumulation at point sources - search for muon neutrinos with high energy: upward and downward (with extreme high energy) - search for cascades with high energy - search for point sources

15 Search for diffuse excess of extraterrestrial high energy neutrinos

16 Search for a TeV-PeV excess in the diffuse flux (upward going muons) AGN with 10-5 E -2 GeV -1 cm -2 s -1 sr -1 atm.n 1997 B10-data, PRL 90 (2003), hit photomultipliers ( channels ) as energy indicator cut Exp. - cuts for best sensitivity obtained from MC - NO significant excess E 2 F(E) < GeV cm -2 s -1 sr -1

17 Search for a PeV-EeV excess in the diffuse flux (downward muons and muons close to horizon) EHE events very bright; many PMTs detect multiple photons vertical Experiment CORSIKA R m 10 km 10-6 E -2 Neural Net Parameter NN2 for neutrino vs.atm muon separation bright horizontal MC track E 2 F(E) < GeV cm -2 s -1 sr -1

18 Synthesis 1: Limit on diffuse flux for muon neutrinos Limits for generic E -2 spectra and specific model shapes: GeV: E 2 F(E) < GeV cm -2 s -1 sr GeV: E 2 F(E) < GeV cm -2 s -1 sr -1 prel. Expected sensitivity 2000 data: ~ GeV cm -2 s -1 sr -1

19 Diffuse limit from cascades Electromagnetic and hadronic cascades PRELIMINARY ~ 5 m n e :n m :n t =1:1:1 for E 2 F(E) =10-6 GeV cm -2 s -1 sr -1 expect 9.3 n e, 3.8 n m, 6.2 n t events 2 candidate events total observed E 2 F all n (E) < GeV cm -2 s -1 sr -1

20 Synthesis 2: flux limits for all flavours assuming n e :n m :n t =1:1:1 multiplicative factor 3 applied for single n m channel e-production on Glashow resonance (6.3 PeV): - n e + e ÆW Æn + e - 90% CL limit GeV -1 cm -2 s -1 sr -1 e - cascades: n e + n m + n t 2000 n m analysis will yield all-flavour limit comparable to cascade limit

21 Search for extraterrestrial point sources

22 Point source search in AMANDA II Search for excess events in sky bins for up-going tracks neutrino events observed from below the horizon - 5% non-neutrino background for q > 5 - cuts optimized in each declination band PRELIMINARY below horizon: mostly atmospheric n s 1. Grid Search (sky subdivided into 300 bins ~7 x7 ) 2. Search around defined sources 3. Cluster Search above horizon:mostly fake events no clustering observed - no evidence for point sources

23 Selected point source flux limits sensitivity ª flat up to horizon, in average 4 times better than B10! PRELIMINARY declination averaged sensitivity: F n lim ª cm -2 s 90%CL Sources declinatio SS433 n 5.0 o M o Crab 22.0 o Mkn o Mkn o Cyg. X o Cas. A 58.8 o upper 90% CL in units of 10-8 cm -2 s -1 published Ap. J, 582 (2003)

24 m cm -2 s southern sky 4 years Super-Kamiokande northern sky 170 days AMANDA-B10 8 years MACRO sensitivity for AMANDA SS declination (degrees) Mk-501 n/g ~ 1

25 Is there a signal at higher energies? no indication of clustering also at higher energies! (us incre e N asi (PM ng T) ener as gy en de erg po y m sitio ea n su re )

26 Search for WIMPs

27 c n 1. Neutrinos from the Center of Earth c + c Æ b + b soft spectrum Æ Æ W + + W - hard spectrum

28 Looking to the center of the earth No statistically significant excess of vertical muons on top of the expected atmospheric neutrino background Number of events NO WIMP SIGNAL DETECTED cosine (zenith)

29 Upper limits on the muon flux coming from neutralino annihilations in the center of the Earth Improvement of upper limits from 99-data analysis compared to 97-data analysis is due to the larger 1999 effective live time the development of cuts adapted to each WIMP mass individually Baikal-98/99 AMANDA-97 AMANDA-99

30 c 2. Neutrinos from the Sun c n Amanda At South Pole the Sun sinks maximally 23 below horizon. Therefore only Amanda-II with its considerably improved reconstruction for horizontal tracks (compared to Amanda-B10) can be used for solar WIMP search.

31 sensitivitiy on the muon flux coming from neutralino annihilations in the center of the Sun AMANDA-II results: based on 193 days of live time Exclusion sensitivity from analyzing the off-source bins Will un-blind data soon and look to the Sun. ANTARES and ICECUBE: MC-calculated sensitivities

32 - Cosmic ray composition

33 cosmic ray composition studies SPASE-2 (electron component) - AMANDA B10 (muon component) - unique combination! Iron AMANDA (number of muons) log(e/pev) Proton AMANDA II Spase (number of electrons) robust evidence for composition change around knee...

34 Composition change around knee ev ev blue band: detector and model uncertainties red band: uncertainty due to low energy normalization A=30 confirms trend seen by other experiments... A= data publication in preparation

35 Summary - AMANDA complete since 2000: 19 strings, 677 OMs - results presented from 97/98 (B10) and 2000 (A-II) - atmospheric muons: vertical muon intensity - atmospheric n: energy spectrum (1 100 TeV) - search for extraterrestrial n: limits on excess of diffuse flux at high E n limits on excess of diffuse flux at extreme high E n (muons from horizon and above) limits for point sources no effect seen up to now: limits at level of most optimistic model expectations - search for n resulting from WIMP annihilations: center of earth: limit center of sun: sensitivity (competitive to results from direct search)

36 Outlook - complete analysis of 2000 data: excess of diffuse flux of HE neutrinos WIMPs from earth and sun - improve search for magnetic monopoles: extend search to non-relativistic monopoles - combined analysis of : factor 4 in statistics - FADC readout: registration of single photoelectron: improved reconstruction and analysis for high energy events