Thoughts about a L1 trigger

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The GZK limit and the search for particle point
sources at the Pierre Auger Observatory
Charles Timmermans
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The Auger Observatory
1400 m height 875 g/cm2
Total area 3000 km2

• Low population density
• Good atmospheric conditions
  (clouds, aerosol)

1600 water tanks 1.5 km spacing 24
fluorescence telescopes, 6 in each of 4 buildings
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Current Status (15/12/2007)
4 Fluorescence detectors running 1570 tanks
deployed 1530 with water 1471 with
electronics 1600 tanks expected in February
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Water Tank in the Pampa
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Fluorescence Telescope
Spherical mirror (R3.4 m)
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Example Event A hybrid event 1021302Zenith
angle 30º, Energy 8 EeV
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Example Event A hybrid event 1021302Zenith
angle 30º, Energy 8 EeV
Fitted Electromagnetic Shower
from Fly's Eye 1985
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Energy Calibration
S38(1000) surface density at 1 km from the
shower core for showers coming in at 38 degrees.
387 events
EFD A x S B eV B 1.13 0.02
FD energy (22 syst.)
Fluorescence yield from Nagano et al.
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Consistency of our data
Comparison of three statistically independent
spectra
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The Measured Spectrum
Slope -2.62 0.03
Exp Obs gt1019.6
132 /- 9 51 gt 1020 30 /- 2.5
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Calibration unc. 18
FD syst. unc. 22
5165 km2 sr yr 0.8 full Auger year
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The GZK-effect
P. Gorham, SSI 2007
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Magnetic Field Directionality
Extra-galactic fields are not expected to be a
dominating factor at energies beyond 50 EeV
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Magnetic Field Directionality
Simulated angle due to galactic B-field between
original direction and arrival direction for 60
EeV protons
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Anisotropy Search
Using data taken before 27 may 2006, a
prescription was formulated with respect to
opening-angle, AGN-redshift and threshold. Only
after rejecting isotropy at the 99 level a
positive claim was made!
ALL Data
ALL Data
ALL Data
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Highest Energy Events
AGN Catalog Veron-Cetty Veron
318 AGNs in field of view observatory
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Angular Separation to AGN
Isotropic Distribution
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Conclusions

• The Pierre Auger Observatory is producing physics
  results
• The measured energy spectrum is consistent with
  the observation of the GZK-cutoff
• The highest energy events are NOT isotropically
  distributed
• There is a clear correlation with nearby AGNs

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The Pierre Auger Collaboration
Aim To measure properties of UHECR with
unprecedented statistics and precision
necessary even if no disagreement