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Pierre Auger Observatory
for UHE Cosmic Rays
Gianni Navarra (INFN-University of Torino)
for the Pierre Auger Collaboration
• Science Case: the need for Auger
• Principles and Advantages of a
Hybrid Detector
• Present Status of the Observatory
• First preliminary Data
• Perspectives
XXXXth Rencontres de Moriond
ElectroWeak Interactions and Unified Theories
La Thuile 5-12th March 2005
Pierre Auger Collaboration
16 Countries
50 Institutions
~350 Scientists
Italy
Czech Republic
France
Germany
Greece
Poland
Slovenia
Spain
United Kingdom
Spokesperson: Alan Watson
Argentina
Australia
Brazil
Bolivia*
Mexico
USA
Vietnam*
*Associate
Countries
UHE Cosmic Rays
Surface particle detectors
Eo >1020 eV: 1 part / (km2 century sr)  102 – 103 km2 collecting areas
UHE Cosmic Rays
atmospheric
fluorescence detectors
Atmospheric fluorescence detectors
Eo >1020 eV: 1 part / (km2 century sr)  102 – 103 km2 collecting areas
HiRes vs AGASA
~ 30 %
Syst. Error
Surface particle detectors
HiReS
Atmospheric fluorescence detectors
D. Bergmann
AGASA
GZK?
Cosmic ray sources are close by (<100 Mpc)
pair production energy loss
B intergalactic
B = 1 nG
3 Gpc
pion production energy loss
pion production rate
1021 eV
2mN m  m
Eth 
 4 1019 eV
4
2
Dq ~ degree
 Sources !!!
-
Relic Particles in Galactic Halo ?
Sakar & Toldrà, Nucl.Phys.B621:495-520,2002
Toldrà, astro-ph/0201151
2
8
16
+ Composition (p,…Fe,g,n)
+ Astronomy (point sources)
Mrelic = 1022 eV; SUSY evolution, n-body decay
Required to solve EHECR-Puzzle:
• Better understanding of Syst. Errors
• Better Resolution in Energy and Direction
Hybrid Approach:
Independent EAS-observation techniques
Shower-by-Shower in one Experiment
• Much more Statistics
 Much larger Experiment
UHE Cosmic Rays with Auger
Atmospheric fluorescence detectors
Atmospheric fluorescence detectors
Surface particle detectors
Atmospheric fluorescence detectors
Eo >1020 eV: 1 part / (km2 century sr)  102 – 103 km2 collecting areas
Southern Site
Pampa Amarilla; Province of Mendoza
3000 km2, 875 g/cm2, 1400 m
Surface Array:
Lat.: 35.5° south
LOMA AMARILLA
1600 Water Tanks
1.5 km spacing
3000 km2
Fluorescence Detectors:
4 Sites
6 Telescopes per site (180° x 30°)
24 Telescopes total
70 km
View of Los Leones
Fluorescence Site
Six Telescopes viewing 30°x30° each
Schmidt Telescope
using 11 m2 mirrors
UV optical filter
(also: provide protection
from outside dust)
Schmidt corrector ring
opt. Filter
(MUG-6)
Camera with 440 PMTs
(Photonis XP 3062)
Los Leones
(fully operational)
Morados
handed to Collaboration 1.9.04
Coihueco
(fully operational)
Lomo Amarilla
(in preparation)
Aligned Water Tanks
as seen from Los Leones
Water Tank in the Pampa
Communication
antenna
GPS
antenna
Electronics enclosure
40 MHz FADC, local
triggers, 10 Watts
Battery
box
Solar Panel
three 9”
PMTs
Plastic tank
with 12 tons
of water
Installation Chain
installation of electronics
receiving tanks
Tank Preparation and Assembly
Transportation into field
Water deployment
Southern Site as of Febr. 2005
Coihueco
650 Water Tanks (out of 1600)
> 10 x AGASA
+ 12 Telescopes
AGASA
Los Leones
Calibration
SD Calibration by Single Muon Triggers
Agreement with
GEANT4 Simulation
up to 10  VEM
(Vertical Equivalent
Muons).
Sum
PMT 1
PMT 2
PMT 3
VEM
Peak
Local
EM Shower
VEM ~ 100 PE /PMT
Huge Statistics!
Systematic error
~5%
Base-Temperature
vs Time
tank response& monitoring
SDSingle
calibration
single muons
Noise
Signal-Height vs Time
Signal-Height vs Base-Temp
± 3%
Huge Statistics!
Systematic error ~5%
Absolute: End to End Calibration
FD Calibration
N Photons at diaphragm
 FADC counts
A Drum device installed at the aperture uniformly illuminates the camera
with light from a calibrated source (1/month)
Mirror
Camera
Calibrated
light source
Diffusely reflective drum
Relative: UV LED + optical fibers (1/night)
Alternative techniques for cross checks
• Scattered light from laser beam
• Calibr. light source flown on balloon
Drum from outside
telescope building
All agreed within 10%
for the EA
Atmospheric Monitoring
• LIDAR at each eye
• cloud monitors at each eye
• central laser facility
• regular balloon flights
steerable LIDAR
facilities
located at each FD eye
Central laser facility
(fibre linked to tank)
LIDAR at each FD
building
light attenuation length
Aerosol concentration
Balloon probes  (T,p)-profiles
Performance
demonstrated
by
First Preliminary Data
Vertical (q~35o) & Inclined (q~72o)
14 tanks
35 tanks
14 km
~ 7 km
Energy ~ (6-7) 10 19 eV
~ 13 km
Young & Old Shower
‘old’ shower
‘young’ shower
Vertical vs Horizontal Showers
n
Only a neutrino can induce a young horizontal shower~ 0.2
! µs
‘young’ showers
• Wide time distribution
• Strong curvature
• Steep lateral distribution
‘old’ showers
• Narrow time distribution
• Weak curvature
• Flat lateral distribution
A Big One: ~1020 eV, q ~60°
34 tanks
~60°
~ 8 km
(m)
~ 14 km
Lateral Distribution Function
2020
~10
eV
~110
eV
propagation time of 40 µs
EAS as seen by FD-cameras
Two-Mirror
event
EAS as seen
by FD-cameras
Only pixels with ≥ 40 pe/100 ns are shown
(10 MHz FADC  ≤ 4 g/cm2; 12 bit resol., 15 bit dynamic range)
Pixel-size = 1.5° ; light spot: 0.65° (90%)
1019 eV events trigger up to ~ 30 km
Energy Reconstruction
Integral of
Longitudinal Shower Profile
 Energy
~ 4.8 Photons / m / electron
(~ 0.5 % of dE/dx)
preliminary
A Stereo Hybrid; q ~70°
…zoom
~70°
Coihueco
Fluores. Telescope
~37 km
Lateral Distribution Function
~8·1019eV
~24km
Los Leones
Fluores. Telescope
global view
A stereo hybrid; q ~70°
~37 km
~24km
A stereo hybrid; q ~70°
Shower Profile
~7·1019eV
(SD: ~8·1019eV)
The Power of Hybrid
Observations
 SD times
x
y
y
Verified by using central laser facility
Mono 26.15 ± 0.55 km
Hybrid 25.96 ± 0.02 km
Mono
vs Hybrid: uncertainties of
Shower core & angle of incidence
mono
hybrid
 FD times
Some numbers:
data taking from Jan. 2004
SD: number of tanks in operation 650
fully efficient above ~ 3.1018 eV
number of events ~ 120,000
reconstructed ( > 3fold, >1018 eV) ~ 16,500
at present ~ 600 events/day
FD: number of sites in operation 2
SD+FD: number of hybrids 1750
~ 350 “golden”
Preliminary
Sky Plot
no energy cut applied
Auger-S >85o
Auger-S >60o
Distribution of Nearby Matter
7-21 Mpc
Auger-S >60o
Auger-N >60o
Jim Cronin, astro-ph/0402487
AUGER NORTH
Two Candidate Sites
15,000km2
Utah
Colorado
10,000km2
“Standard”
3,100 km2
Auger North
(3,100 km2)
TA
(800km2)
CONCLUSIONS
Auger construction in rapid progress in south
Physics data taking since January 2004
Stable operation, excellent performance
Hybrid approach is a great advantage!
Neutrino sensitivity
First physics results by summer 2005
Energy spectrum
Sky map
Auger North proposal in progress
Pampa Amarilla