VHEPU Mar-2005 P. N édélec - LAPP Air Fluorescence Light Yield Measurements Summary of the IWFM05 Workshop Thanks to IWFM05 speakers

VHEPU Mar-2005 P. N édélec - LAPP 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

VHEPU Mar-2005 P. N édélec - LAPP Who is interested? HiRes (and AGASA) Auger EUSO, TUS, KLYPVE, OWL,… Telescope Array

VHEPU Mar-2005 P. N édélec - LAPP Extensive Air Shower Interaction UHECR/atmosphere Charged tracks on groung (AGASA, AUGER,TA,…) Air Fluorescence (HiRes, AUGER,TA, EUSO,TUS,…) + Č erenkov

VHEPU Mar-2005 P. N édélec - LAPP Shower & Atmosphere properties Shower Max 2-13 km (0 o -80 o ) FLY should varies with: Pressure Temperature Components (H 2 O,…) o C atm

VHEPU Mar-2005 P. N édélec - LAPP Bremsstrahlung N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 O2O2 N2N2 N2N2 N2N2 N2N2 O2O2 O2O2 O2O2 N2N2 Ar N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 O2O2 O2O2 e - (high energy) N2N2 N2N2 O2O2 Ar N2N2 N+2N+2 N2N2 Electron induced Air excitation N+2N+2 N+2N+2 Ionisation N+2N+2 γ N+2N+2 N+2N+2 O-2O-2 N 2 and N 2 + excitation

VHEPU Mar-2005 P. N édélec - LAPP N2N2 N2N2 N2N2 N2N2 N2N2 N2N2 Air De-excitation N2+N2+ Fluorescence: UV UV light emission Collision: Increase of temperature No UV light produced Competition between different processes: Decay Time / Collision Time N2+N2+ N2+N2+ N2N2 N2+N2+ N2N2

VHEPU Mar-2005 P. N édélec - LAPP Wave length (nm) Fluorescence Light Yield Spectrum Between 300 et 400 nm The Space Window Incertainties on FLY measurements: 30% Davidson et O’Neil (1964) Bunner (1967)

VHEPU Mar-2005 P. N édélec - LAPP What to measure? Air & N 2 FLY as a function of: Reproduce & study in laboratory the light induced by an atmospheric shower Pression (0 to 1 atm ) Temperature (-50 → 20 o C) Air composition (O 2, Ar…) Impurities (humidity, aerosol…) Particule energy Particule density Particule nature ( e -,, , , p…) Shower age (#X 0 ) Cherenkov contribution Lifetimes N 2 for ref. comparison

VHEPU Mar-2005 P. N édélec - LAPP 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 H. Brunet, PhD thesis, Toulouse,1973: –“Destruction des états C 3  u de N 2 dans l’azote pur et mélange avec O 2, H 2 O, CO 2,CH 4” –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 %

VHEPU Mar-2005 P. N édélec - LAPP A New Field emerged Goal: understand the fluorescence yield to better than 10 %

VHEPU Mar-2005 P. N édélec - LAPP NameParticle sourceNumber of particles Particle energy Nagano * 90 Sr β0.85 MeV Airlight 90 Sr β2.3 MeV MACFLY 90 Sr β, e -, e +,π,  (CERN) 10,000 per spill 2.3 MeV GeV Coimbra 241 Am (  ), 90 Sr β 2.8 MeV AIRFLYe -, e + (DA  NE) MeV FLASHe - (SLAC) <1 MeV – 28.5 GeV Madride - gun keV TU Muniche - gun12 keV Brazil, Paris.. * : published paper(s) Experimental approach: Spectroscopy:  ~ 1 nm Narrow band filters:  ~ 10 nm Large band filters:  ~ 100 nm

VHEPU Mar-2005 P. N édélec - LAPP Published Nagano Results (reference) 15 wave bands measured with a 13% systematic uncertainty using narrow Band filter (Astropart. Phys. 22 (2004) 235)

VHEPU Mar-2005 P. N édélec - LAPP Nagano(cont.) FLY ~ 3.3 – 3.9 photons/m/e 1atm

Tilo Tilo WaldenmaierInternational Workshop on Fluorescence MeasurementsHabère-Poche, 4th February 2005 The AirLight Experiment Experimental Setup 90 Sr Electron Source: 90 Sr Electron Source: –Endpoint Energy:2.3 MeV –Activity:37 MBq Scintillator:10 – 20 kHz 7 Photon Detectors:7 Photon Detectors: –Electrostatic + magnetic shielding  low dark rates, stable operation  low dark rates, stable operation –Dark rates: 400 – 500 Hz over thr. –1 MUG-6 filter –6 narrow band filters (FWHW: , 360, 380, 337, 391, , 360, 380, 337, 391, 427 nm Gas:Gas: –N 2, Air –Pressure range:1 hPa – 1000 hPa –Temperature: ~ 16 °C

VHEPU Mar-2005 P. N édélec - LAPP

VHEPU Mar-2005 P. N édélec - LAPP

IWFM 05 MF1: Air pressure dependence DL In Air for 50GeV e - at 28°C Fluorescence : FLY = E dep. C/(1+P/P’) Cerenkov : CDL = α P/P atm, α =0.6 mpe Background : Cst = 1.6 mpe Results: C =0.76±0.1 photon/keV P’ = 23.5 ±5 hpa DL (mpe) DL = FLY x ε MF1 + CDL + Cst Fit with 2 free parameters C and P’ measurement G4 simuVacuum measurement G4 simu + calibration G4 simu Fly/E dep in photon/keV FLY air (P atm ) = ph/keV Preliminary results

IWFM 05 MF1 vs other experiments Kakimoto et al (96) Bunner: (300 to 406) Nagano et al (04) (300 to 406 nm) Air Fly in photon/meter for 50GeV e - at 28°C Macfly air FLY : 9% less than Nagano 8% more than Kakimoto 6% more than Bunner Preliminary results

VHEPU Mar-2005 P. N édélec - LAPP

IWFM 05 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)

IWFM 05 MF1: Energy Dependence Energy air FLY at 950 hpa ≃ 1.5 MeV 3.2 ph/m 20 GeV5.6 ph/m 50 GeV5.7 ph/m Air Fluorescence Light Yield FLY (ph/m) Kinetic Energy (MeV) Macfly Kakimoto dE/dX curve Preliminary results

VHEPU Mar-2005 P. N édélec - LAPP

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

Raw data (  particle excitation) P 0 =818 hPa  = 0,80   P 0 =688 hPa  = 0,68   P 0 =434 hPa  = 0,43   P 0 = 520 hPa  = 0,51  o P 0 = 600 hPa  = 0,59  o

VHEPU Mar-2005 P. N édélec - LAPP

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VHEPU Mar-2005 P. N édélec - LAPP 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?

VHEPU Mar-2005 P. N édélec - LAPP