Performance of the AMANDA-II Detector R.Wischnewski for the AMANDA Collaboration; DESY-Zeuthen, Germany AMANDA-II Detector  Largest High Energy Neutrino-Detector ever built:An open Under-Ice Cerenkov Detector for high energy muons and showers.  19 vertical strings with 677 Optical Modules (OM): 8 inch PMTs with analog pulse transmission to surface.  Construction started in fall 1995, full detector commssioned in early 2000.  Different technologies applied:  strings 1-10: analog electrical pulse transmission  strings 11-19: analog fiber pulse transmission  1 test string with Digital OM technology (IceCube prototype) AMANDA-B10 The various analog OMs used in AMANDA-II: electrical and fiber readout modules, and the digitally controlled module (from left to right). For Digital OM see H.E.2.05 Results obtained with the10 string detector AMANDA-B10 (1997 data)  Isolation of 325 atmospheric vμ achieved - proof of performance (Nature,2001) - HE2.03  Limits on flux of HE diffuse vμ/ve-flux (AGN) - HE2.03  Limits on v-flux from point sources and GRB and UHE-v - HE232/236  Limit on WIMPs, on relativistic magnetic Monopoles and galactic Supernova v‘s - HE231 AMANDA-II Signal Expectation First Analysis Astrophysical sources: AGN, GRB, SN-shells, topological defects,... with spectra much harder than v‘s generated in the atmosphere Assume a diffuse AGN E-2 spectrum: 10-6 E-2 GeV sr-1 s-1 cm-2  Trigger level acceptance of vμ and v e Charged Current (CC) and Neutral Current (NC) interactions: Trigger: majority trigger (>23 OMs in 2.5 μs) and local cluster trigger external: EAS-array SPASE Data sample: 1.3 TB raw data in ca. 250 run days in 2000 MC-data comparison at trigger and higher v-cut levels  number of hit PMTs (nOM), angular-distributions, pass.-rates fit well  absolute rates & vertical hit structure under study (ice, noise) Data-analysis for AMANDA-II/2000 has started. Preliminary v -cuts developed. Triggered events / year Atmospheric AGN vμ 11000 (CC) 130 (NC) 853 (CC) ve 162 (CC) 9 (NC) 103 (CC) Atm AGN vμ Number of hit optical modules per event, nOM(dots- exper., histogram -MC). ve Neutrino energy spectrum for events, triggering AMANDA-II: CC vμ-events (thick lines) and CC ve-events (thin lines) for atmospheric neutrinos (full lines) and AGN like neutrinos (dashed-dotted lines). Zenith angle distribution for atmospherci nmu MC events in AMANDA-II (full line), compared to AMANDA-B10 detector (dashed). Preliminary cuts, normalized for vertical bin. An AMANDA-II v-candidate close to the horizon, May 2000. Conclusions  AMANDA-II is in stable operation and delivers high quality muon and neutrino data.  Neutrino-event selection is much improved over AMANDA-B10 by better geometry and better OM timing.  Neutrino event-rates will be at least 3 times larger compared to B10.  Angular acceptance is much improved for horizontal tracks, opening full lower hemisphere for HE-neutrino astronomy.  DAQ-Upgrade planned for 2001/02 for improved HE/UHE sensitivity. Reconstructed zenith angle cos(Θreco) (left) and azimuth angle Φreco (right, in degress) at trtigger level