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Air Fluorescence Light Yield Measurements

Air Fluorescence Light Yield Measurements. Summary of the IWFM05 Workshop http://lappweb.in2p3.fr/IWFM05/. Thanks to IWFM05 speakers. Purpose. Understand (better) and Calibrate the Air Fluorescence Light Yield (FLY) Estimate the quality of the “air” as a scintillator

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Air Fluorescence Light Yield Measurements

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  1. Air Fluorescence Light Yield Measurements Summary of the IWFM05 Workshop http://lappweb.in2p3.fr/IWFM05/ Thanks to IWFM05 speakers P. Nédélec - LAPP

  2. Purpose • Understand (better) and Calibrate the Air Fluorescence Light Yield (FLY) • Estimate the quality of the “air” as a scintillator • Understand experimental uncertainties • Hires – Agasa controversy P. Nédélec - LAPP

  3. Who is interested? • HiRes (and AGASA) • Auger • EUSO, TUS, KLYPVE, OWL,… • Telescope Array P. Nédélec - LAPP

  4. Interaction UHECR/atmosphere Air Fluorescence (HiRes, AUGER,TA, EUSO,TUS,…) + Čerenkov Extensive Air Shower Charged tracks on groung (AGASA, AUGER,TA,…) P. Nédélec - LAPP

  5. Shower Max 2-13 km (0o-80o) Shower & Atmosphere properties • FLY should varies with: • Pressure • Temperature • Components (H2O,…) 0.2 1 atm -50 +20 oC P. Nédélec - LAPP

  6. Ionisation Ar N2 N2 N2 N2 N2 N2 N2 N2 N+2 N2 N2 O2 N2 N2 N2 N2 O2 O2 O2 N2 N2 N2 N+2 N2 N2 N2 N2 N2 N2 N2 N2 O2 N2 O2 O2 N2 N+2 N2 N+2 N+2 N+2 N2 O-2 Electron induced Air excitation e-(high energy) γ Bremsstrahlung Ar N2 and N2+ excitation P. Nédélec - LAPP

  7. N2+ N2+ N2+ N2+ N2 N2 N2 N2 N2 N2 N2 N2 Air De-excitation Fluorescence: UV UV light emission UV Collision: Increase of temperature No UV light produced Competition between different processes: Decay Time / Collision Time P. Nédélec - LAPP

  8. Wave length (nm) Fluorescence Light Yield Spectrum Between 300 et 400 nm The Space Window Davidson et O’Neil (1964) Bunner (1967) Incertainties on FLY measurements: 30% P. Nédélec - LAPP

  9. What to measure? Reproduce & study in laboratory the light induced by an atmospheric shower Air & N2 FLY as a function of: N2 for ref. comparison • Pression(0 to 1 atm ) • Temperature (-50 → 20 oC) • Air composition (O2, Ar…) • Impurities(humidity, aerosol…) • Particule energy • Particule density • Particule nature(e-,,, m, p…) • Shower age(#X0) • Cherenkov contribution • Lifetimes P. Nédélec - LAPP

  10. History - References • A.N. Bunner, PhD thesis, Cornell, 1967: • “Cosmic Rays detection by Atmospheric . Fluorescence” • Nitrogen fluorescence spectrum between 300 and 400nm • Compilation • Error ~ 30 % on yield at each l • H. Brunet, PhD thesis, Toulouse,1973: • “Destruction des états C3Pu de N2 dans l’azote pur et mélange avec O2, H2O, CO2,CH4” • Rediscovered at Bad Liebenzell (second workshop) • Kakimoto et al. (1995): • measurement of total yield between 300 and 400 nm • three lines (337 nm, 357 nm, 391 nm) • Error > 10 % P. Nédélec - LAPP

  11. A New Field emerged Goal: understand the fluorescence yield to better than 10 % P. Nédélec - LAPP

  12. Experimental approach: • Spectroscopy: Dl ~ 1 nm • Narrow band filters: Dl ~ 10 nm • Large band filters: Dl ~ 100 nm P. Nédélec - LAPP * : published paper(s)

  13. Published Nagano Results(reference) 15 wave bands measured with a 13% systematic uncertainty using narrow Band filter (Astropart. Phys. 22 (2004) 235) P. Nédélec - LAPP

  14. Nagano(cont.) FLY ~ 3.3 – 3.9 photons/m/e- @ 1atm P. Nédélec - LAPP

  15. Experimental Setup • 90Sr Electron Source: • Endpoint Energy: 2.3 MeV • Activity: 37 MBq • Rate @ Scintillator: 10 – 20 kHz • 7 Photon Detectors: • Electrostatic + magnetic shielding  low dark rates, stable operation • Dark rates: 400 – 500 Hz over thr. • 1 MUG-6 filter • 6 narrow band filters (FWHW: 10 nm) @ 317, 360, 380, 337, 391, 427 nm • Gas: • N2, Air • Pressure range: 1 hPa – 1000 hPa • Temperature: ~ 16 °C

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  18. MF1: Air pressure dependence DL In Air for 50GeV e- at 28°C DL = FLY x εMF1 + CDL + Cst Fluorescence : FLY = Edep . C/(1+P/P’) DL (mpe) Cerenkov : CDL = α P/Patm , α =0.6mpe Background :Cst = 1.6 mpe G4 simu Vacuum measurement measurement G4 simu + calibration Fly/Edep in photon/keV G4 simu Fit with 2 free parameters C and P’ • Results: • C =0.76±0.1 photon/keV • P’ = 23.5 ±5 hpa Preliminary results FLYair (Patm) = 0.0172 ph/keV

  19. MF1 vs other experiments Air Fly in photon/meter for 50GeV e- at 28°C Nagano et al (04) (300 to 406 nm) Kakimoto et al (96) Bunner: (300 to 406) Macfly air FLY : 9% less than Nagano 8% more than Kakimoto 6% more than Bunner Preliminary results

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  21. Shower age dependence Detected light in air for primary 50GeV e- at 25°C Blue : 500 hpa Red : 100 hpa ------ :GIL model (50 GeV e- in Cu)

  22. Macfly Kakimoto dE/dX curve MF1: Energy Dependence Air Fluorescence Light Yield Preliminary results FLY (ph/m) Kinetic Energy (MeV)

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  24. Experimental set-up –July 2004 Cooling unit PM3 scintillator Cooling Box PM1, PM2 - XP2020Q PM3 – R1166 to vacuum pump Pressure sensor

  25. Raw data (a particle excitation) P0 = 600 hPa r = 0,59 ro P0=818 hPa r = 0,80 ro P0=688 hPa r = 0,68 ro P0 = 520 hPa r = 0,51 ro P0=434 hPa r = 0,43 ro Temperature dependance

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  34. Outlook • Delicate measurements – Goal 10% syst. • All the projects are “Running Experiments” • Lines + Filters measurements performed • Pressure dependence (all) • Temperature (Coimbra, AirFly) • First Shower age FLY measurements • MacFly, FLASH • Simulation G4 • Needed, mature • Absolute calibration • Cerenkov, Rayleigh,… • Difficult, needed • Theory/Models • improving Where the FLY story ends? P. Nédélec - LAPP

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