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Physics Laboratory

S. E. Tzamarias. Physics Laboratory. School of Science and Technology. Hellenic Open University. HOU Contribution to WP4 (Information & Technology). KM3Net Kick-off Meeting, Erlangen-Nuremberg , 11-13 April 2006.

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Physics Laboratory

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  1. S. E. Tzamarias Physics Laboratory School of Science and Technology Hellenic Open University HOU Contribution to WP4 (Information & Technology) KM3Net Kick-off Meeting, Erlangen-Nuremberg, 11-13 April2006 The project is co-funded by the European Social Fund & National Resources EPEAEK-II (PYTHAGORAS)

  2. Example: Earth Absorption Probability of a νμ to cross Earth Example: νe interacting inside a grid-like detector Nadir Angle Events Generator • Atmospheric Muon Generation Extensive Air Showers • Neutrino Interactions (use of Pythia) • Neutrino (all flavors) Induced Events • Atmospheric Neutrinos • Cosmic Neutrinos (Several Models) • Production of Secondaries, • transportation, energy loss

  3. Monte Carlo Development : Simulation Technique Cherenkov photon emission Define 2 points inside the detector, p1 & p2 For all PMTs Which point is closer ? p1 p2 Add PMT to group2 Add PMT to group1 find the center of mass m1 of group1 find the center of mass m2 of group2 no is m1=p1 and m2=p2 yes converge A new, very efficient, general purpose, Cherenkov simulation algorithm Stage 1:Define PMT clusters according to the detector geometry Stage 2: Use the Clusters for the Cherenkov photon production The simulation strategy is applicable and efficient for any detector architecture without any extra optimization

  4. Monte Carlo Development : Simulation of the Detector Response (GEANT4) General purpose: Simulation of (any) PMT Response Simulation of electronic functions mV Angular Distribution of Cherenkov Photons EM Shower Parameterization Parameterization of EM Shower • Number of Cherenkov Photons • Emitted (~shower energy) • Angular profile of emitted photons • Longitudal profile of shower

  5. Simulation Example K40 Noise Hits Signal Hits 1 TeV Vertically incident muon (Hit amplitudes > 2p.e.s)

  6. Current Studies • PMT orientation and photon directionality • nested vs uniform architecture for ~1TeV muons • fast triggers and filtering algorithms • detector calibration using EAS Computer Power • Computer Farm with 15 computers (15 double xeons ) • We are currently installing 64 more computers (64 double opterons) 350 Gflops

  7. Fast Triggering Algorithms Estimation of Information Rate 1km3 Grid (18522 15inch PMTs) Information Rate = PMT Number * K40 Noise Rate * (Bytes/Hit) = 18522 * 50kHz * 32 ≈ 30GB/sec Cannot be saved directly to any media

  8. Charge & Multiplicity Characteristics Charge/hit distribution signal noise Number of pes No Cut 1TeV Vertical Muons Multiplicity (noise) Number of active PMTs in 6 μs window Multiplicity (signal) Number of active PMTs in 6 μs window

  9. Charge & Multiplicity Characteristics Selection based on hits with at least 2 photoelectrons Information Rate = PMT Number * K40 Noise Rate * (Bytes/Hit) = 18522 * 3kHz * 32 ≈ 1.8GB/sec Multiplicity (noise) Multiplicity (signal) By Using clustering like DUMAND the background rate is reduced by 75% (450 MByte/sec) and the signal hit has a higher than 60% probability to survive

  10. Fast Triggering Algorithms Estimation of Information Rate 1km3 Grid (18522 triplets of PMTs) 3 PMTs per hemisphere in coincidence Each triplet’s total photocathode = 15inch PMT photocathode 10nsec time window, 2 out of 3 coincidence Triplet coincidence rate=17Hz (17kHz background per PMT) Information Rate = PMT Number * K40 Noise Rate * (Bytes/Hit) = 3* 18522 * 17 Hz * 32 ≈ 30MB/sec

  11. Fast Triggering Algorithms Background 1TeV Vertical Muons Signal Number of active triples Distributions normalized to 1 Use of the number of activate triplets as fast selection trigger

  12. Fast Triggering Algorithms Event Rate (kHz) Cut to the number of active triplets Efficiency Cut to the number of active triplets Estimation of Event Rate and Efficiency 180 kByte/event 10TeV 1TeV

  13. Fast Triggering Algorithms Use also the Dumand clustering: 1TeV Vertical Muons Background Signal Number of active triples

  14. Fast Triggering Algorithms 180 kByte/event Event Rate (kHz) Cut to the number of active triplets 1TeV Efficiency Cut to the number of active triplets Estimation of Event Rate and Efficiency

  15. Fast Triggering Algorithms Raw Hits Absolute time Time Stretching Trigger Level trigger Accepted Interval Triggering Method

  16. Alternative Options for photodetection Large photocathode area with arrays of small PMTs packed into pressure housings 36 PMs in 3 subcylinder 35 3” photomultipliers in a cylinder Determination of photon direction, e.g. via multi-anodic PMs plus a matrix of Winston cones.

  17. t1 t2 t3 Ethernet H.O.U., Univ. Athens, Univ. Patras, INP DEMOKRITOS, NTUA A. Leisos

  18. A Station GPS Scintillator Scintillator ~20 m Scintillator Scintillator TCP/IP PC A. Leisos

  19. Eurocosmics

  20. Detector calibration using EAS The General Idea… • Angular offset • Efficiency • Resolution • Position

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