absolute measurement of air fluorescence yield for ultra-high energy cosmic rays paolo privitera...
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![Page 1: Absolute Measurement of Air Fluorescence Yield for Ultra-High Energy Cosmic Rays Paolo Privitera Carlos Hojvat Fermilab, June 27 2008 FD SD](https://reader035.vdocuments.mx/reader035/viewer/2022062322/56649eef5503460f94bff3ba/html5/thumbnails/1.jpg)
Absolute Measurement of Air Fluorescence Yield for Ultra-
High Energy Cosmic Rays
Paolo Privitera
Carlos Hojvat
Fermilab, June 27 2008
FD
SD
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Auger results
Flux suppression
Anisotropy < 75 Mpc
Astrophysical interpretation GZK horizon
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Auger Energy Calibration
Lateral density distribution
Fluorescence Detector
Surface Detector
The largest systematic uncertainty is the air fluorescence yield (15%)
The Auger energy scale is based on the FD calorimetric energy.
10 km
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The Auger hybrid detector concept
300-400 nm light from de-excitation of atmospheric nitrogen (fluorescence light)
≈ 4 γ’s / m /electron
1019 eV 1010 e
Light attenuation in the atmosphere; showers develop in 15 km
• Fluorescence spectrum
• Dependence on pressure, temperature and humidity
• Absolute yield 20
FD
SD
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AIRFLY measurements
391.4 nm337.1 nm
353.7 nmrelative band intensities
Temperature and humidity dependence
Pressure dependence
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Chemistry Division Van de Graaf (0.6-3 MeV)
Advanced Photon Source (6-30 KeV)
HEP Division Advanced Wakefield Accelerator
(3 MeV-15 MeV)
AIRFLY beams
Beam Test Facility at DANE INFN FRASCATI (50-750 MeV)
ARGONNEANL
Collaboration: Cezch Republic, Germany, Italy, US
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Chamber
Gas system
Vacuum pump
Lead shielding support
BTF (Frascati)
Argonne Chemistry VdG
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Absolute Fluorescence Yield at the Fermilab Meson Test Beam
Goal: ≤ 5% uncertainty with the fluorescence/Cherenkov ratio method
Photon Detector
Particle beam
Fluorescence photons
Cherenkov photons
Photon Detector
Particle beam
45° mirror
(a) (b)
337 nm filter
Q.E uncertainty >10% Normalize to known yield: Q.E cancels
Tested at Frascati and Argonne
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Absolute Fluorescence Yield at the Fermilab Meson Test Beam
Fluorescence/Cherenkov ratio method + independent laser calibration
• Low intensity: Integrating sphere, Ultra Bialkali PMTs (43% QE)
Particle beam
Photon Detector
Integrating sphere
Diffuser to be placed for Cherenkov run
Cherenkovdump
Acceptance counter
Veto counter
• High energy (reduce multiple scattering, air as Cherenkov Radiatior)
• Well defined beam: single particle trigger and geometry
• Wide range of particles type and intensity
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Collaborative Initiative Grant
• Crucial measurement for Auger (South and North); will have a strong impact in the Auger scientific results and in the UHECR field
• Use of Fermilab facility: Meson Test Beam• University of Chicago and Fermilab have a long history of collaboration in Auger; Auger design Workshop
held at Fermilab in 1995• Collaboration well matched for the success of the initiative• P. Privitera (Chicago), C. Hojvat (Fermilab), H. Spinka (Argonne), AIRFLY collaborators • Some hardware from AIRFLY• Funds: 1 postdoc (100% FTE), hardware for new chamber • 2 years proposal
Tank n. 1600
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Air fluorescence spectrum
• Argonne 3 MeV electron VdG, DC beam, 10 μA• Spectrograph instead of monochromator:Insensitive to changes of beam intensity or position
VdG Beam
Sphericalmirror
Optical fiber
L.O.T. Oriel MS257 = 0.1 nm
Andor CCD DV 420
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Chamber
Gas system
Vacuum pump
Lead shielding support
BTF (Frascati)
HPD