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Preliminary estimate of performances using a 2-telescope system

Preliminary estimate of performances using a 2-telescope system. CTA meeting. E. Carmona on behalf of the MAGIC collaboration. Berlin, 5 May 2006. Objective. Estimate performances of a next generation CTA, optimized for low energy g ray showers Assuming current technology, but with:

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Preliminary estimate of performances using a 2-telescope system

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  1. Preliminary estimate of performances using a 2-telescope system CTA meeting E. Carmona on behalf of the MAGIC collaboration Berlin, 5 May 2006

  2. Objective • Estimate performances of a next generation CTA, optimized for low energy g ray showers • Assuming current technology, but with: • Large light collection area (Ø 23 m) • High QE detectors (Si PMs) • Simulate a 2 telescope system. Later, scale the results by the number of pairs • Done by using MAGIC-II Monte-Carlo data and analysis tools • DATA: same reflector files used for MAGIC II studies CTA Meeting

  3. MAGIC II MAGIC-II MAGIC-I • Second Ø17 m telescope close to MAGIC I (~85 m) • MC study showed a factor ~2 improvement in sensitivity when going from 1 to 2 telescope • Distance between telescopes not critical CTA Meeting

  4. Parameters of the simulation • Simulation parameters: • Ømirror = 23 m (estimated from 17 m) • f/D = 1 (FIXED) • Improved Reflectivity: 85% - 95% • Camera FoV up to 4.7º • Camera with different number of pixels • Camera pixels: SiPM, 50% QE, 10% gain fluctuations • 3NN trigger • FADC 2 Gs/s • Distance between telescopes: 90 m (FIXED) • Events analysed only in stereo mode • Aperture (Amirror×Ref×QE) ~168 m2 – MAGIC I ~26 m2 CTA Meeting

  5. Simulation and analysis chain • g and proton showers produced with Corsika (v. 6.019) • Photons on ground reflected with Reflector (atmospheric absorption) program: Reflector files • Camera simulation: • New pixel response (SiPM) • Different number of pixels • Calibration • Hillas parameters from camera output • g / hadron separation using Random Forest MAGIC II CTA CTA Meeting

  6. MC events • From 10 GeV to 10 TeV • 2×106 gammas, 20 files • From 100 GeV to 10 TeV • ~1.4×107 protons, 1411 files • Low energy proton production, 50 GeV – 100 GeV • ~3.5×107 protons, 3450 files • Very low energy proton production, 30 GeV – 50 GeV • ~1×107 protons, 1014 files • Gammas • Protons • Estimate of other backgrounds added later: • 50% proton rate increased (accounts for other hadrons) • Rough estimate of e flux (extrapolated from g results) CTA Meeting

  7. Camera simulation • Hexagonal camera and pixels • f/D = 1 • Example: • 3571 pixels, 0.067º • 4.65º FoV • 3.30º Trigger • Different cameras have been simulated: • 3571 Pixels, 0.067º (4.65º FoV, 3.3º trigger) • 3571 Pixels, optimistic optics • 1657 pixels, 0.067º (3.3º FoV, 3.3º trigger) • 1519 Pixels, 0.10º (4.54º FoV, 3.2º trigger) • 721 Pixels, 0.10º (3.2º FoV, 3.2º trigger) CTA Meeting

  8. g images NO NOISE NO NOISE CTA Meeting

  9. g images CTA Meeting

  10. Energy threshold • High photon collection efficiency allows to go down in energy Number of events after computing Hillas parameters No g/h separation CTA Meeting

  11. g/h separation • Is done with Random Forest • Mean scaled width and length are useful parameters for separation CTA Meeting

  12. g/h separation • g/h separation improves with size 3571 pixels 50<size<150 3571 pixels 150<size<300 3571 pixles 300<size<600 3571 pixels 600<size<1000 3571 pixels 1000<size<2000 CTA Meeting

  13. Effective area for gammas 3571 pixels, 4.7º 1519 pixels, 4.7º 721 pixels, 3.3º 1657 pixels, 3.3º CTA Meeting

  14. Angular Resolution(q containing 50% g in q2 plot) 3571 pixels, 4.7º 1519 pixels, 4.7º 1657 pixels, 3.3º 721 pixels, 3.3º CTA Meeting

  15. Flux sensitivity 3571 pixels, 4.7º 1519 pixels, 4.7º 1657 pixels, 3.3º 721 pixels, 3.3º CTA Meeting

  16. Improved spread function • Optimistic optical PSF of photons • Differences only important for low E CTA Meeting

  17. Electron estimate • Electron flux estimated from g showers from 10 to 100 GeV. Assuming: • Electron flux: 1.2×10-3 E-1 (1 + (E/5 GeV)2.3)-1 cm-2 sr-1 s-1 GeV-1 • Hadronness of electronsequal to gs • Flat distribution in q2 • Effect is small, because of q2 cut CTA Meeting

  18. CT array flux limits CTA Meeting

  19. Conclusions • 2-telescope with high light collection efficiency (mirror area and QE) has been studied • Simple analysis without any improvement can lower the energy threshold of a CT to ~10 GeV (lower?) • Pixel size has a small effect at low energies • Smaller pixels allow an improvement in angular resolution and flux sensitivity • Improving psf of photons before camera (better optics) might be important to improve performance at low energies • Electron flux not a problem, efficiently reduced with q2 CTA Meeting

  20. To be done • Study energy resolution • Use time in the analysis • Use 3 or more telescopes in coincidence • Change geometry of the array CTA Meeting

  21. SiPMs • Flat 50% QE between 300 – 600 nm • Gain fluctuations of 10% introduce in camera • NSB factor for SiPM 2.4 (w.r.t. EMI coated) CTA Meeting

  22. Proton images CTA Meeting

  23. Camera Output • Full simulation of camera performed. Output is data in the RAW data format of MAGIC • Size of the raw output files and simulation time is a problem: • Gammas → 21.8 Gb, ~25 hours for 105 showers • Protons → 540 Mb, ~1 hours for 104 showers • Protons low E→ 96 Mb, ~20 minutes for 104 showers • Protons very low E → 210 Mb, ~100 minutes for 105 showers • The whole simulation-analysis process has been automatized • Only a small part of the data is finally stored CTA Meeting

  24. g/h separation CTA Meeting

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