Upload
adler
View
48
Download
2
Tags:
Embed Size (px)
DESCRIPTION
Fermilab, June 27 2008. Absolute Measurement of Air Fluorescence Yield for Ultra-High Energy Cosmic Rays. Paolo Privitera. Carlos Hojvat. FD. SD. Auger results. Flux suppression. Anisotropy < 75 Mpc. Astrophysical interpretation GZK horizon. - PowerPoint PPT Presentation
Citation preview
Absolute Measurement of Air Fluorescence Yield for Ultra-
High Energy Cosmic RaysPaolo Privitera
Carlos Hojvat
Fermilab, June 27 2008
FD
SD
Auger results
Flux suppression
Anisotropy < 75 Mpc
Astrophysical interpretation GZK horizon
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
The Auger hybrid detector concept300-400 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
AIRFLY measurements
391.4 nm 337.1 nm
353.7 nmrelative band intensities
Temperature and humidity dependence
Pressure dependence
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
Chamber
Gas system
Vacuum pump
Lead shielding support
BTF (Frascati)
Argonne Chemistry VdG
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
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
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
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 nmAndor CCD DV 420
Chamber
Gas system
Vacuum pump
Lead shielding support
BTF (Frascati)
HPD