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Fluorescence Yield Measurements for Ultra-High Energy Cosmic Rays Study

This study focuses on measuring the fluorescence yield for Ultra-High Energy Cosmic Rays to better understand the nature, origin, and processes of these high-energy particles. With a need for accurate energy measurements and flux understanding, the research delves into the behavior of cosmic rays through air showers, particle interactions, and fluorescence emission. Techniques like Cerenkov cone detection, surface detector calibration, and extrapolation of cross-sections are employed to study cosmic ray properties. The aim is to achieve precise and absolute calibration of detectors to accurately measure fluorescence spectra within specific wavelengths for in-depth analysis.

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Fluorescence Yield Measurements for Ultra-High Energy Cosmic Rays Study

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  1. Measurement of the Fluorescence Yield for UHECR study Gwenaëlle LEFEUVRE APC – Collège de France

  2. Cosmic Rays • Fluorescence • Yield Measurements

  3. Ultra-High Energy Cosmic Rays Energy max. ? Nature ? Origin ? Processes ?

  4. The need of an accurate energy 15 % in energy almost 40 % in flux * E3 !

  5. Air shower Cosmic ray • some 103 hadrons • some 109 electrons Fluorescence (isotropic) Cosmic ray Charged particles Nuclei Electromagnetic part : 90 % of total energy ! Cerenkov cone

  6. Detecting the UHECR • Sampling • extrapolation of cross sections • AGASA, Auger • Fluorescence • development of the shower • HiRes, Auger, EUSO Today : Auger calibration of surface detector by fluorescence

  7. What is the fluorescence ? Excitation e-sh + N2 e- + N2+* + e-sh e- + N2+ N2* e- + N2 e- + N2* Bunner, PhD thesis, 1967

  8. Fluorescence spectrum • « Dry air » (80 % N2, 20% O2), 1 bar • after correction of spectrometer response • electron gun, 1013 e-/s Intensity (rel. unit.) Wavelength (Ulrich, Airlight workshop, 2003)

  9. Yield (photons / m) De-excitation of nitrogen • Radiation • Internal • Collision • Recombination : O2 Null pressure f(P, T) Pressure (hPa) photons / e- / meter

  10. US-Standard 76 atmosphere Temperature Density Pressure

  11. Yield variation with altitude Models Measurements

  12. Yield variation with altitude 13.5 %

  13. Already, my result...

  14. Absolute yield in [300, 430] nm with the best accuracy possible Absolute fluorescence spectrum Objectives To achieve this : need an accurate and absolute calibration of the detectors

  15. the setup

  16. the setup 370 MBq

  17. the setup

  18. the setup

  19. the setup BG3 (Schott) Transmission (%) wavelength (nm)

  20. the setup

  21. the setup

  22. the setup

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