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SIM : Fluorescence Yield From Lab to EAS in atmosphere

SIM : Fluorescence Yield From Lab to EAS in atmosphere. Photon yield to be used in SIM-WG ? Which set of data ? Which set of parameters? some aspects. Fluorescence in N 2. Excited bands: B 2 S u (N2+) : direct Under particle impact C 3 P u (N2) : 2-step Electron exchange

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SIM : Fluorescence Yield From Lab to EAS in atmosphere

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  1. SIM : Fluorescence YieldFrom Lab to EAS in atmosphere • Photon yield to be used in SIM-WG ? • Which set of data ? • Which set of parameters? • some aspects Didier Lebrun Huntsville, May 2003

  2. Fluorescencein N2 Excited bands: B2Su (N2+) : direct Under particle impact C3Pu (N2) : 2-step Electron exchange Under very low impact energy (secondary electrons) Didier Lebrun Huntsville, May 2003

  3. Fluorescence parameters & their influence on yield • Fluorescence efficiencies in N2 in (N2 & Air) • Transition band • Impact energy • Mixed gas and quenching (O2, Water…) • Collision quenching , Internal quenching? • Other scintillation centers in Air ? • EAS parameters • Energy-loss distribution of e-m component & Age effect • Detection optical bandwidth Photon Yield / electron /meter in Air Didier Lebrun Huntsville, May 2003

  4. Yield Didier Lebrun Huntsville, May 2003

  5. Water Vapor Quenching ofN2 (2P) fluorescence As for O2 quenching is due to high electron attachment cross-section no quenching for 1N (391nm) Standard humidity profile Didier Lebrun Huntsville, May 2003

  6. Fluorescence Data • Data used so far • Bunner thesis (compilation) • Davidson & O’Neil (N2,Air, Monochromator,) • Kakimoto (Energy dependence) . Ueno (1.4 MeV) • Nagano (0.85 MeV,Coll.P) NEW : FY Increases • Other Data • LAX (22 keV X, BG1) • Data from Laser Physics (N2) , Atmospheric Physics (aurora), Plasma physics (discharge), Particle physics detectors ( electron drift in gas) Didier Lebrun Huntsville, May 2003

  7. Starting with2P transition at very low pressure Relative transition strength at s max: Exp : Fons et al Phys.ReV A 53(1996)2289 Th : Franck-Condon transition coefficients smax(0,0)=1.07 10-17 cm2 At P = 0.5 mTorr Normalization : only smax(0,0) (337.1) @ electron impact energy (15 eV) Didier Lebrun Huntsville, May 2003

  8. Collision quenching • Pressure (T) dependence measurements. • Wide band filter (LaX) • Narrow band filter (Nagano) • Monochromator (future) • Need good wavelength resolution (~1-2nm) but for head of bands only. LaXdata Calculation with ‘old’ set of parameter Didier Lebrun Huntsville, May 2003

  9. Parameters from EAS • Electron impact energy • Distribution of energy loss frome.m component in EAS • Preliminary study with Corsika tells us that the mean energy loss per particle corresponds to an electron impact energy of 32 MeV. • To be confirmed (depends on ‘thinning’); but it is< critical energy • shower age dependence Didier Lebrun Huntsville, May 2003

  10. Didier Lebrun Huntsville, May 2003

  11. Fluorescence mechanisms&and their influence on extrapolation • One step and two-step processes • 1N and 2P behave very differently • Secondary electron distribution • 2P upper level excitation only under electron impact ? • Excitations from cascading ? • Excitation transfer ? • Argon • Special conditions in EAS ? • screening • 2P1P cascade • Informations from EAS ‘red’ fluorescence ? Didier Lebrun Huntsville, May 2003

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