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Sebastian Kuch, Rezo Shanidze

Sebastian Kuch, Rezo Shanidze. Summary of the Detector Simulation Studies in Erlangen. KM3NeT Collaboration Meeting Pylos, Greece, 16 - 18 April 2007. Introduction. The Summary of the Erlangen detector simulations: Sebastian Kuch, Ph.D-thesis, FAU-PI1-DISS-07-001

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Sebastian Kuch, Rezo Shanidze

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  1. Sebastian Kuch, Rezo Shanidze Summary of the Detector Simulation Studies in Erlangen KM3NeT Collaboration Meeting Pylos, Greece, 16 - 18 April 2007

  2. Introduction • The Summary of the Erlangen detector simulations: • Sebastian Kuch, Ph.D-thesis, FAU-PI1-DISS-07-001 • Design Studies for the KM3NeT Neutrino Telescope • (to be released soon) • Detector performance was simulated for different: • - photo-detector system(s) • - geometry configuration of the detector • Modified ANTARES software, ‘sea model’ and • reconstruction algorithms were used in simulations. KM3NeT, Pylos, Greece

  3. ANTARES software KM3NeT, Pylos, Greece

  4. KM3NeTDetector Models The KM3NeT parameters fixed during simulation: - instrumented volume ~1 km3 ( 1% precision) - overall photocathode area ( ~ 5% ) 1 km3 Main detector element: storey (cluster of PMTs) To avoid overlap of parameters: - same geometry g for different storey types - same storey g for different geometry configurations Detector performance parameter used for the comparison of the different detector models: Effective area nm/m event samples: 10 GeV <En < 10 PeV (En-1.4), 4p –isotropic 2·109nm MC events (standard sample) KM3NeT, Pylos, Greece

  5. Neutrino Effective Area Neutrino Effective Area: (Muon neutrino charged current(CC) interaction effective area) Aneff (E,Q)= Veff(E,Q)·(rNA)·s(E)·PEarth(E,Q) Veff(E,Q) – effective volume: Nx(E,Q)/NG (E,Q)x VG Nx - events selected (with x criteria) NG - events generated in Volume VG r, NA - density and Avogadro number s(E) - neutrino cross-section PEaeth(E,Q) - Probability of n transmission through the Earth: Event rates for a neutrino flux Fn(E,Q): N = ∫ Aneff(E,Q) Fn(E,Q) dE dW KM3NeT, Pylos, Greece

  6. Generation Volume Event generation volume (VG): defined by the m-range at max. nenergy (Em=En=107GeV) VG – not homogenous: a) sea water r1=1.0404 g/cm3 b) non transparent part with r2=2.65 g/cm3 sediments (~1km) and oceanic crust a r1 Path length of muons (m), tauons(t) em and had. showers in water b r2 KM3NeT, Pylos, Greece

  7. Earth Density Profile Probability n transmission throug the Earth: P(En ,cosQn )= exp(-s(En )·d(cosQn )· NA ) a c b log(d) [ g m-2] cos(Qn) Log(En) a)Earth density profile in units of the Earth radius b) Column density as a function of neutrino direction. c) Transmission probability vs. neutrino energy and direction cos Qn KM3NeT, Pylos, Greece

  8. Selection Criteria m • Reconstructed m track : 5 parameters: • - Space point: x, y, z • - Direction: Q, f • Different criteria (x), for the selection of events: Nx • Minimal - corresponds to minimal requirement for m • reconstruction: at least 6 signal hits on • at least 2 storeys. • Moderate - at least 6 storeys hit(includes Minimal ) • Selected - corresponds to event which is selected • (reconstructed) by the modified ANTARES • m-reconstruction algorithm, with angular • error DQm<5o. Q,f (x,y,z) KM3NeT, Pylos, Greece

  9. Simulated Photodetection Systems 3 PMT types simulated: 1) 10” , Hamamatsu R7081 (used in ANTARES, IceCube) 2) 20” , Hamamatsu R3600 (used in SuperKamiokande) 3) 3” , Photonis XP53X2 Multi-PMT configuration 1 10” PMT (1) in a glass sphere 3 2 2 Multi PMT(3”) story configuration Hamamatsu 20” PMT (RS 3600)

  10. Paramters of the PMT List of the PMT parameters used in the simulations: Quantum efficiency QE(l), Angular acceptance, Transit time spread(TTS). QE(l) and angular acceptance of 10” PM (Hamamatsu R7081) KM3NeT, Pylos, Greece

  11. Detector Model for Different Storeys KM3NeT geometry for the different storey/PMT configuration: Example ofstring configurations with large Hamamatsu PMTs. Cuboid geometry [m] [m] 1 2 3 4 5 [m] 1) single OM, 2) double OM, 3) ANTARES 4) twin ANTARES 5) 20” single OM Geometry used for the comparison: 484 strings (22 x 22), Lstring = 567 m, distance between Lines: 63 m

  12. Detectors with 10” PMTs 10” detector with diff, storeys: effective are and their ratio for the minimal and moderate criterion Minimal Minimal Moderate Moderate KM3NeT, Pylos, Greece

  13. Detectors with 10” PMTs 10” detector with diff, storeys: effective are as a function of cosQn and their ratio for the minimal and moderate criterion Minimal Minimal Moderate Moderate KM3NeT, Pylos, Greece

  14. Detectors with 10” PMTs 10” detector with diff. storeys: effective area vs En and cosQn Selected Selected Selected Selected KM3NeT, Pylos, Greece

  15. Detectors with 10” PMTs • Effective area for first two steps (minimal, moderate) are very similar • for all detectors. For moderate level storeys with single PMT are preferable. • Effective area at trigger and reconstruction/selection level depends on • the background conditions and strongly favors the multi-PMT storey • configurations. • The effective area angular dependence is strongly peaked at large • zenith angles (due to the matter density distribution). • Angular resolution for multi-PMT storeys are slightly better than single and • double OM storey detectors. KM3NeT, Pylos, Greece

  16. Detector with Multi-PMT Storey Multi-PMT ( P.Kooijman, NIM A567(2007), 508 ) pro: high QE, short TTS, good 2-photon separation, stability contra: lack of experience, cost QE and angular acceptance (‘flat disc”) for 3” PMT (XP53X2) used in the Multi-PMT storey detector simulations KM3NeT, Pylos, Greece

  17. Configurations with Multi-PMT Storey Different Multi-PMT storey layouts: 1) ‘cylindrical’ : 12 PMT/cylinder ( ~ 10’’ photocathode area) ANTARES type story: 3 Multi-PMT cyl: 36 PMT 2) Spherical storey (17” sphere): - 42 PMTs ( 4p –max possible) (8 storey/L, 82 m spacing) - 36 PMTs ( 4p ) - 21 PMT ( 2p) (20 storey/L, 31.5 m spacing) KM3NeT, Pylos, Greece

  18. Detector with Multi-PMT Storey Selected selected Selected Selected KM3NeT, Pylos, Greece

  19. Detector with 20” PMT Storey large effective photocathode area / low QE, large TTS, low purity of selected hits 2 configurations: a) single PMT/Storey b) ANTARES storey (with ~ 4x ph. cathode area) Moderate Moderate Selected Selected KM3NeT, Pylos, Greece

  20. Photodetection Systems: Summary • Photocathode area ( x QE) is most important factor defining the Neutrino • Detector effective area. • Single PMT/storey detectors have poor background (40K) rejection • capabilities and have worst performance with used m-reconstruction • algorithms. • Multi-PMT storey with (3” PMT) provides promising alternative to • ANTRES like configurations ( with 10” PMTs). • For the same photocathode area Multi-PMT detectors have additional • advantages, such as larger number of storeys (for 21 PMT configuration) • and better PMT parameters. • Simulations of the different photo-detector layouts indicate that a multi- • PMT storey detector might be the preferable choice. KM3NeT, Pylos, Greece

  21. KM3NeT Detector Geometries 5 different types of geometries are considered: 1-3) Cuboid, ring, clustered geometries (13 configurations) 4) IceCube comparable (ICC), ( 4 configurations) Ring geometry Cluster geometry Cuboid geometry Same storey is used for these configurations: ANTARES type Multi-PMT (3 x 12 X 3”PMT) storey (cyl)

  22. KM3NeT Cuboid Geometries KM3NeT, Pylos, Greece

  23. KM3NeT Cuboid Geometries Selected Selected Selected Selected KM3NeT, Pylos, Greece

  24. KM3NeT Ring Geometries ( see also talk of P.Vernin, WP2_2006@Marseille) Ring 1 Ring 2 Ring 3 Ring 4 KM3NeT, Pylos, Greece

  25. Ring Geometries Moderate Moderate Selected Selected KM3NeT, Pylos, Greece

  26. Ring Geometries Moderate Moderate Selected Selected KM3NeT, Pylos, Greece

  27. KM3NeT Clustered Geometries Main motivation: increase of efficiency at low neutrino energies. Cluster 1 Cluster 2 Cluster 3 KM3NeT, Pylos, Greece

  28. Clustered Geometries Selected Selected Selected Selected KM3NeT, Pylos, Greece

  29. Comparison with IceCube IceCube: Astropart.Phys.20(2004),507 IceCube KM3NeT density r 0.9 (ice) 1.04 (sea water) Absorption length (m) 50- 150 60 Background rate < 1 kHz 40 kHz Use of IceCube configuration was suggested at WP2 meeting (Marseille, Oct. /2006) Inter-storey/Line separation 17 / 125 m Number of lines /storey line 80 /60 Orientation of OMs Downwards Height of first storey 100 m Site Characteristics: Depth of sea bed 2450 m IOP: absorption length: 60 m, no scattering, refraction index 1.35(450 nm) PMT : 10” Hamamtsu ( with photocathode area= 500 cm2, “flat disk” acceptance) KM3NeT, Pylos, Greece

  30. IceCube Comparable Geometry Detectors with different geometries but same IceCube type lines (IceCube comparable ICC) and storey : ICCcube, ICCring, ICCcluster, with Lstring=1000 m IceCube ICCcluster ICCcube ICCring KM3NeT, Pylos, Greece

  31. IceCube Comparable Geometry Selected Moderate Moderate Selected KM3NeT, Pylos, Greece

  32. Detectors Geometries: Summary • Different detector configurations for 1km3 instrumented volume • (cube, ring, clustered, IceCube comparable). • Within considered detector configurations there is no single one • which is preferable at all considered energies (10 < En < 107 GeV) • For low energies (En < ~103 GeV) clustered and ring geometries • have larger effective area. • For high energy (En > 103 GeV) effective area for cube and ring type • configurations are very similar, effective area for the clustered • configurations are significantly worse. • Detector with cuboid configuration (Cube 2) was selected as an • example detector for the further studies. KM3NeT, Pylos, Greece

  33. Example of KM3NeT detector + + 21 3” PMTs per storey 36 storeys per string 225 strings (15 x 15) KM3NeT, Pylos, Greece

  34. KM3NeT Effective Area The neutrino Effective area (Aeff(En)) of the “Example detector” at different selection steps. The true Aeff(En) will be between minimal and selected (reconstructed) criteria. KM3NeT, Pylos, Greece

  35. Summary and Outlook • Different models for the KM3NeT detector were simulated, • corresponding to several photo-detection systems and geometrical • configurations. • For considered KM3NeT models neutrino effective area were • calculatedand compared for the selection of ‘KM3NeT candidate • configurations’. • For the Mediterranean Neutrino Telescope the ANTARES-type or • Multi-PMT storey detector has a significant advantage in background • reduction, event triggering and reconstruction. • Photocathode area of the detector is the most important parameter • in the effective area calculations. • Optimization of m-reconstruction and selection criteria is necessary • step in the selection of the final configuration. KM3NeT, Pylos, Greece

  36. KM3NeT Effective Area The neutrino Effective area (Aeff(En)) of the “Example detector” at different selection steps for the up-going neutrinos. The true Aeff(En) will be between minimal and selected (reconstructed) criteria. KM3NeT, Pylos, Greece

  37. 2p / 4p Effective Areas a Ratio of neutrino effective area (Aeff(En)) of the “Example detector” for up-going neutrinos (2p) to effective area for all neutrino directions (4p). Line corresponds to the 4p case, dashed line to 2p/4p effective area ratios for a) minimal, b) moderate and c) selected (reconstructed) levels. For Low Energies due to the fact that detector is looking down 2p areas are better. At high energies, were absorption In the earth is dominant effect, 4p areas are superior. b c KM3NeT, Pylos, Greece

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