RESULTS FROM AMANDA. Carlos de los Heros Division of High Energy Physics Uppsala University. CRIS04 Catania, Italy, May 31-June 4

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1 RESULTS FROM AMANDA Carlos de los Heros Division of High Energy Physics Uppsala University CRIS04 Catania, Italy, May 31-June 4

2 The AMANDA/ICECUBE Collaborations Bartol Research Institute UC Berkeley UC Irvine Pennsylvania State UW Madison UW River Falls LBNL Berkeley U. Simón Bolivar, Caracas VUB-IIHE, Brussel ULB-IIHE, Bruxelles Université de Mons-Hainaut Imperial College, London DESY, Zeuthen Mainz Universität Wuppertal Universität Stockholm Universitet Uppsala Universitet Kalmar Universitet South Pole Station 150 members + University of Maryland, US Clark-Atlanta University, US Southern University, US IAS, Princeton, US University of Alabama, US University of Oxford, UK University of Utrecht, NL Chiba University, Japan U. of Canterbury, Christchurch, NZ as ICECUBE members

3 NEUTRINO ASTRONOMY Cosmic >>TeV exist acceleration sites must sit somewhere SNe remnants } Active Galactic Nuclei proton Gamma Ray Bursts accelerators Exotics (decays of topological defects...)? explained by SN unexplained Guaranteed sources: atmospheric neutrinos (from π & K mesons decay) galactic plane: CR interacting with ISM, concentrated on the disk CMB (diffuse): UHE p γ + n π + (p π 0 ) Neutrinos : not absorbed, not deflected: difficult to detect Protons : deflected in magnetic fields, GZK γ-rays : propagate straight, however: reprocessed in sources absorbed in IR (100 TeV) and 3K (10 PeV)

4 THE AMANDA DETECTOR O(km) long muon tracks determination of the trajectory by Cherenkov light timing 19 strings 677 PMTs trigger rate: 80 Hz PMT noise rate: 1 khz Θµν 1.5 ( E ν / TeV) m need up/down rejection 10-6 background from atmospheric muons

5 ALL FLAVOUR DETECTION Electromagnetic and hadronic cascades ν τ : oscillation + regeneration at PeV important no EM / hadronic cascade differentiation (even if slightly different shape and lower light output for hadronic cascades) ~ 5 m

6 TWR UPGRADE Transient Waveform Recorder system installed between the 2001 and 2004 campaigns Increased OM dynamic range x ~100 Increased 1pe detection efficiency Virtually dead-time free Manageable trigger rate: ~150 Hz (majority 18) Possibility of using software trigger Physics benefits: Improved angular resolution Improved energy resolution UHE/EHE physics

7 THE SITE geographic South Pole AMANDA 2km deep

8 DETECTOR MEDIUM: ICE PROPERTIES in-situ light sources atmospheric muons ice optical parameters: λ abs ~ nm λ scatt ~ nm

9 DETECTOR CAPABILITIES muons: directional error: σ(log( E/E)): coverage: 2π showers: (e ±, τ ±, neutral current) zenith error: σ(log( E/E)): coverage: (5TeV < E < 5 PeV) 4π 5m 2 ν µ effective area (schematic): E ν 2 ν-interaction in earth, detector response primary cosmic rays: (+ SPASE2) energy resolution: cm GeV 100 TeV 100 PeV

10 AMANDA can operate in very different energy regimes Energy range analysis ~MeV SN ν production site(s) Supernovae GeV - ~TeV atm ν atmosphere Dark matter Sun/Earth TeV - PeV diffuse AGN, GRB cascades point sources PeV EeV UHE AGN, TD > EeV EHE? Agreed collaboration strategy: Analyses are done blind. cuts optimized on a % of data or on a time-scrambled data set. (except for SN searches where analysis is based on detector noise rate

11 AMANDA PHYSICS TOPICS Cosmology / Particle Physics / Astrophysics primary CR spectrum: atmospheric neutrinos (also calibration/background of Amanda) CR composition (with surface detector SPASE-2) CR origin (acceleration sites: AGN, GRBs) extra-terrestrial flux (diffuse / punctual / >TeV energies Dark matter / exotic particles: neutralinos, magnetic monopoles, extra dim. WIMP s signature: Excess from the Sun/Earth s center direction heavy and slow particles SN monitor of the Milky Way Topological defects: extra-terrestrial UHE diffuse flux low energy EM cascades (global noise increase throughout AMANDA)

12 TeV-PeV DIFFUSE FLUX 10-5 E -2 GeV -1 cm -2 s -1 sr -1 cut atm.ν Exp. data sample 97: 10 9 evts data 2000 analysis on the way hit channel multiplicity as energy indicator cuts optimized for best sensitivity Above optimal cut N ch >54: N obs = 3 evts N atm ν = 3.06 ± 25% norm± ~35% sys NO EXCESS OBSERVED assuming a E -2 flux (6 TeV < E ν < 1 PeV) : PRL 90 (2003), E 2 Φ νµ (E) < GeV cm -2 s -1 sr -1

13 TeV-PeV DIFFUSE FLUX: LIMITS Comparison to other experimental E -2 limits Limits for other flux predictions: N ch cut optimized for each case. Expected limit from a given model compared with observed limit. Some AGN models excluded at 90% CL (marked as X below) Stecker et al, Phys Rev Lett , Szabo-Protehoe 92 Stecker, Salamon. Space Sc. Rev. 75, 1996 Protehoe. ASP Conf series, 121, 1997 X X X

14 HE DIFFUSE FLUX (cascades( cascades) 2000 data sample, 197 days lifetime. 1.2x10 9 trigger level sim. BG: atm. muons (920 d) atm. neutrinos After optimized cuts : N obs = 1 evts N atm µ = N atm ν = ± 25% norm no earth propagation effects ν τ ν e ν µ

15 HE DIFFUSE FLUX (cascades( cascades): LIMITS sensitivity to all three flavors assuming a E -2 flux: E 2 Φ all ν (E) < GeV cm -2 s -1 sr -1 ( ν e :ν µ :ν τ =1:1:1) paper submitted to Phys. Rev. D for specific models: some AGN core-production models 90% CL (dashed in figure) From data sample 97, 130 days lifetime (5 TeV < E ν < 300 TeV): E 2 Φ all ν (E) < GeV cm -2 s -1 sr -1 ( ν e :ν µ :ν τ =1:1:1) E 2 Φ ν e (E) < GeV cm -2 s -1 sr -1 Phys. Rev. D67, 2003

16 UHE neutrinos Simulated UHE event µ ν Experiment CORSIKA MC E ν > ev: Earth opaque Search in the upper hemisphere and close to horizon Increased ν-xsection (but uncertainties at these energies) Long µ tracks (> 10 Km) 10-6 E -2 Neural Net parameter for neutrino vs. atm muon separation Bright events low atm µ background Energy -related variables best handle of analysis

17 UHE neutrinos: : Limits PRELIMINARY Data sample: d livetime Average all angles ν effective area vs log Eν NO EXCESS OBSERVED Horizontal events N obs = 5 evts N bck = 4.6 ± 36% evts assuming a E -2 flux (1 PeV < E ν < 3 EeV) : E 2 Φ all ν (E) < GeV cm -2 s -1 sr -1 ( ν e :ν µ :ν τ =1:1:1) paper in progress

18 POINT SOURCE SEARCHES Search for an event excess in the northern sky grid: sky subdivided into 300 bins ~7 x7 (zenith dependent) between 0 o < δ < 85 o cuts optimized in each declination band Eff. area vs µ energy (2000 data) PRELIMINARY sensitivity flat up to horizon, (in average 4 times better than 1997 analysis, Astrophys. J. 583, 2003 ) Sensitivity X 10-7 GeV -1 cm -2 s -1 2 independent analyses in 2000 zenith X1.8 improvement by combining 2 yrs of data. Work in progress

19 POINT SURCE SEARCHES: FLUX LIMITS below horizon: mostly atmospheric ν s (this means northern sky) above horizon:atm µ events 2000 data: upper limits in units of 10-7 cm -2 s -1 E ν >10 GeV, assumed E-2 spectral shape 699 neutrino events observed from below the horizon (2000 data) <10% non-neutrino background for θ>5 no clustering observed: no evidence for point sources declination averaged sensitivity (integrated above 10 GeV) : Φ ν lim cm -2 s -1 Phys. Rev. Lett. 92, ,2004

20 POINT SURCE SEARCHES: FLUX LIMITS Upper limits in units of 10-8 cm -2 s -1 for an assumed E -2 neutrino spectral shape integrated above E ν =10 GeV on some selected sources:

21 SEARCH FOR ν µ CORRELATED WITH GRBs 10 min Low background analysis due to both space and time coincidence! Year 1997 Detector B-10 N Bursts 78 (BT) N BG, Pred 0.06 PRELIMINARY N Obs Event U.L B (BT) Catalogs: BATSE, IPN3 Analysis is blind: finalized off-source (±5 min) with MC signal B-10 A-II (2 analyses) A-II A-II 96 (BT) 44 (BT) 24 (BNT) 46 (New) / / / Ψ<20 + other event quality parameters A-II B-10/A-II 114 (All) 312 (BT) BG stability required within ±1 hour from burst µ effective area m 2 (BT = BATSE Triggered BNT = BATSE Non-Triggered New = IPN & GUSBAD) Flux Limit at Earth: E 2 Φ ν 4x10-8 GeV cm -2 s -1 sr -1 For 312 bursts w/ Broken Power-Law Spectrum (E break =100 TeV, Γ=300)

22 SPASE/AMANDA: CR composition 369m AMANDA 1500m SPASE (scintillator 3000m, ~685 g cm -2 ) e surface shower core resolution: 0(m) shower direction resolution: < 1.5 o AMANDA µ >1500m (>300 surface) use SPASE core position for combined fit use expected lateral photoelectron/event distribution as estimate of N µ AMANDA (number of muons) ln(a) Iron log(e/pev) Proton SPASE-2 (number of electrons)

23 SPASE/AMANDA: CR composition (cont cont.) Combined SPASE-AMANDA detector : Probes hadronic (µ) and EM (e) energy in the primary shower σ(e) ~ 0.07 in log(e prim ) Results compatible with composition change around the knee Sources of systematic uncertainties: (~30% in ln(a), not shown in the plot) -shower generation models -muon propagation Amanda-B10 / Spase-2 CR composition: paper accepted in Astropart. Phys.

24 OUTLOOK First results from AMANDA-II published (2000 data) Amanda-II detector shows greatly improved capabilities Sensitivity at the level of current predictions of ν production in AGN. Some models 90CL combined analysis on its way papers from analysis of data in progress digitized readout since 2003: waveform resolution ice description mature: being fully implemented in MC first IceCube strings in 2004/05 antarctic season