Post on 17-Jan-2016
ICHEP `06, Moscow The Auger project – status and results
G. Matthiae
University and Sezione INFN of Roma “Tor Vergata”
Study of the highest energy cosmic rays • 17 Countries: Argentina, Bolivia, Australia, Brazil,
Rep.Ceca, France, Germany, Italy, Mexico, Netherlands, Poland, Portugal, Slovenia, Spain, UK, USA, Vietnam.
• About 300 physicists
1 particle/km2/century
p + γ 2.7 K → N+ π
Above Ethr ≈ 7*1019 eV, protons loose rapidly energy via pion photoproduction. Interaction length ≈ 6 Mpc Energy loss ≈ 20 % / interaction
Greisen-Zatsepin-Kuzmin
• AGASA sees a continuation of the spectrum beyond the GZK suppression
• Dashed curve represents the spectrum expected for extragalactic sources distributed unifomly in the Universe.
• Extremely poor statistics - only 11 events above 1020 eV
Auger hybrid detector Fluorescence Detector (FD)
• Longitudinal development of the shower
• Calorimetric measurement of the energy
Calibration of the energy scale
• Direction of the shower
12% duty cycle !
Surface Detector (SD)
• Front of shower at ground
• Direction of the shower
• “High” statistics
Southern Observatory (Argentina)
• Very low population density (< 0.1 / km2)
• Very good atmospheric conditions (clouds, aerosol…)
35o S latitude 69o W longitude
≈ 1400 m height ≈ 875 g/cm2
Very flat region“Pampa Amarilla”Malargüe (Argentina)
Future plan for Northern Observatory inColorado (USA)
50 km
Total area ~3000 km2
1600Surface detectors (“water tanks”)
1.5 km spacing
24 fluorescence telescopes 6 in each of 4 buildings
The Auger Observatory
About ¾ installed and operational
Completion in 2007
A surface detector (“water tank”) installed in the Pampa
Water Tank in the Pampa
Solar PanelElectronics enclosure40 MHz FADC, local triggers, 10 Watts
Communication antenna
GPS antenna
Batterybox
Plastic tank with 12 tons of water
three 9”PMTs
• -response ~ track• e/-response ~ energy
-signal of order em-signal
Inclined: em UP
SD calibration & monitoring
single muons
Noise
Base-Temperaturevs Time
Signal-Height vs Time
Signal-Height vs Base-Temp
Single tank response
Huge Statistics!Systematic error ~5%
± 3%
~100 p.e.
VEM
Vertical Equivalent Muon (VEM)
Doublets
Dia Noche
11m
Time resolution
Low energy events (~ 1015 eV) used to compare the time measurement of each tank
: physical dispersion due~13 ns) Time precision of individual tanks ~ 12 ns
Young & Old Shower‘‘young’ showeryoung’ shower
‘‘old’ showerold’ shower
density falls by factor ~150
… by factor ~4
(m)
~11020eV~1020eV
Lateral Distribution Function
~ 14 km
~ 8 km
One event of high energy:~1020 eV, ~60°34 tanks
~60°~60°
LDFS=A [r/rs (1+r/rs)] -β
rs = 700 mA, β from fit (β= 2-2.5)
S(1000) energy estimator
propagation time of 40 µs
Angular resolution from the surface detector depends on the number of tanks
Improved for hybrid events:
~ 0.6 degrees
The FD telescope (Schmidt optics)Field of view 30x30 degrees
Spherical mirror
PMT camera
Diaphragm
UV Filter
Shutter
The Schmidt optics
C
Spherical aberrationComa aberration
Diaphragm Coma
suppressed
C
C
C
spot
F
Spherical focal surface
Six Telescopes viewing 30°x30° each
Fluorescence Telescope
Spherical mirror (R=3.4 m)
Diaphragm and camera
Diaphragm, corrector ring and camera
Field of view: 300x300
Camera: 440 photomultipliersAperture of the pixels: 1.50
Atmospheric Fluorescence
Nitrogen emission spectrum 300 – 400 nm
Photon yield as a function of heightError about 15%
FD Absolute Calibration
Drum: uniform camera illumination
pulsed light sources, several wavelengths and intensity
light diffusing
Tyvek walls
light flux measured
by absolutely
calibrated PMT About 5 photons/ADC count
FD “TEST BEAM”Central Laser Facility
355 nmSteerable laser
optical fiber
SD tank
Laser Mirror DAQ
Backscattering
(Raman)
Elastic bcks. molecular/Rayleigh &
aerosol/Mie
LIDARAtmospheric absorption
LIDAR Station
Steerable system: “Shoot on shower” technique
Event FD on-line bin=100 ns
Background event
Longitudinal profile of showers from the FD telescopes
Fit with empirical formula of Gaisser-Hillas
Calorimetric measurement of the energy.
Another event well contained
Correction for energy loss (neutrinos, muons)
8 – 12 % at 1019 eV
New upper limit on photon fraction E0>10 EeV
• Xmax from showers longitudinal profile observed by the fluorescence detector
• ΔXmax ≈ 25 g cm-2
• 29 events
events
Distribution of the differences Δγ in standard deviations
between primary photon prediction and data
Δγ = 2 – 3.8
New Photon Limit (29 events)
HP: Haverah ParkA1,A2: AGASA
Constraint on top-down/non acceleration models
End 2009: about 2% limit at 10 EeV, 15% at 35 EeV
16% upper limit
Comparison to AGASA
Energy interval (1.0 – 2.5 EeV), angular scale 20°
2116 / 2159.5 ratio = 0.98 ± 0.02 ±0.01
(22% excess would give 2634 and a 10- excess)
Comparison to SUGAR
Energy interval (0.8 – 3.2 EeV), angular scale 5°
286 / 289.7 ratio = 0.98 ± 0.06 ± 0.01(85% excess would give 536 and a 14.5- excess)
Study of excess from the Galactic Center
Zenith angle dependence of the energy estimator S(1000)
Energy calibration – hybrid eventsEnergy obtained by the calorimetric measurement of the fluorescence detector sets the absolute energy scaleSimulation not needed.
log10 S(1000)
log10 E (EeV)
FD energy
Absolute calibration of the energy estimator S(1000) Corrected to 38 degrees
Statistics is now about ½ year of full Observatory (~7000 km2 sr yr) Efficiency =100% above 3 EeV
Systematic error onthe energy ±~ 25%
Auger