IDAPP 2D Meeting, Ferrara, May 3 2007. Claudio Di Giulio University of Roma Tor Vergata, INFN of Roma Tor Vergata. The origin and nature of cosmic rays above 10 19 eV is not understood…. 38° South, Argentina, Mendoza, Malargue 1.4 km altitude. The physics case.
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IDAPP 2D Meeting, Ferrara, May 3 2007
Claudio Di Giulio
University of Roma Tor Vergata,
INFN of Roma Tor Vergata
The origin and nature of cosmic rays above 1019 eV is not understood…
38° South, Argentina, Mendoza, Malargue 1.4 km altitude
The physics case
Auger aims to measure the properties of the highest energy cosmic rays with unprecedented precision.
Status Southern Observatory Malargue, Argentina
1600 detector stations
1.5 Km spacing
6 Telescopes per“Eye”
24 Telescopes total
Last L.A. pmt!!
~ 1300 SD tanks, AllFD data taking.
300-400 nm light from de-excitation of atmospheric nitrogen (fluorescence light) ≈ 4 γ’s / m /electron
1019 eV 1010 e
Cross-calibration, improved resolution, control of systematic errors
The Auger hybrid detector concept
Lateral Distribution Function
Plastic tank with 12 tons of water
3 – nine inch
Shower energy ~ S1000
The Fluorescence Detector
UV filter window
Spherical surface camera
440 PMT with light collectors
Large 300x300 field of view
1.5º pixel fov
3.4 m spherical mirror
Np.e.= ∑ Nγ(λ) A’ ε(λ) T (λ)
Fluorescence Geometry Detector Atmosphere
FD Systematic uncertainties
Tot. ΔE/E ~25%
Alternative Profile Rec. Method: the “spot method”
Claudio Di Giulio – Rome Tor Vergata University
Spot coming from
Inclusion of the
(D.Gora et al.,
➾ Prediction of the expected ADC traces from the hypotized long. profile
➾ Cherenkov contribution from the hypotized profile: NO iteration
➾ Description of the signal on the camera borders and
accounts for camera inhomogeneities (Mercedes)
SD Energy calibration with hybrid events
Simultaneous observation by Fluorescence and Surface Detectors: only ≈10% of events but extraordinary impact on the quality of our physics results!
ESD = A (S38)b
b ~ 1
The power of hybrid…..We DO NOT depend on shower simulation!
Calibration uncertainty improves with hybrid statistics.
FD “Test Beam”
Central Laser Facility
CROSS CHECK OF DRUM CALIB.
CLF (355 nm) 30 Km difficult
Roving (337 nm) 3 Km safer
Drum (375 nm)
May 2005 (Roving+CLF)
August 2006 (Roving)
at the level 10%
Analysis complicated by variable and poor atmospheric conditions
ICRC 2005 p.335-338
 Eventi Stereo dell’Osservatorio Auger, Physics Degree Thesis Università degli Studi di Roma Tor Vergata. ROM2 F/2005/17
 ICRC 2005 (108): The central laser facility at the Pierre Auger Observatory.
GAP-Note 2006-026: A New Methods for the Longitudinal Profile Reconstruction of the Auger Fluorescence Detector Events.
GAP-Note 2006-026: Cross-check of the Fluorescence Detector optical calibration with laser shots.
Astroparticle Physics: In press Accepted Manuscript Measurement of the pressure dependence of air fluorescence emission induced by electrons.