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Solving the Mystery of the Ultra-High Energy Cosmic Rays The Pierre Auger Observatory. Southern Site: Malargue, Argentina Northern Site: Southeast Colorado, USA. Pablo Bauleo Physics Department Colorado State University Fort Collins CO 80523. http://www.auger.org.ar.
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Ultra-High Energy Cosmic Rays
The Pierre Auger Observatory
Southern Site: Malargue, Argentina Northern Site: Southeast Colorado, USA
Pierre Auger discovers
Extensive air showers
Auger varied distance and lead covering
Fast electronic counters
p + CMB p + 0 n + +
Greisen, Zatsepin-Kuzmin (GZK) Cut Off
Particles > 5 * 1019 eV
must be < ~ few*50 Mpc away
Highest energy event:
3.2 x 1020 eV
Fly’s Eye in Utah in 1991
Flux (m2 sr s eV)-1
The Auger project is focused on the highest energies.
Highest energy events are around 2*1020 eV 30 Joules
This energy is concentrated in, say, one proton. It corresponds to kinetic energy of…
…a tennis ball at 40 miles per hour
…dropping my laptop computer from shoulder height
…a person walking slowly, deep in thought.
Flux @ 1020 eV 1 CR/(km2 sr century)
No convincing acceleration process
for explaining particle energy > 1020 eV
A handful of super-GZK events have been reported.
Sources of particles > 1020 eV must be closer than about 50 Mpc because of CMB
No likely acceleration sites have been found nearby.
The highest energy cosmic rays should point back to possible sources
Point sources or uniform on the sky?
The primary cosmic ray initiates a shower.There are two basic detection techniques:
Height ~20 km.a.s.l
Up to order 1011 particles
(2) Nitrogen fluorescence
10% duty factor – dark nights
(1) Particles reach ground
Height ~ 1500 m.a.s.l
Animation of an event
measured in Argentina
Auger south is here.
Malargue is a small town on the high plains not far from a ski area in the Andes.
using 11 m2 mirrors
UV optical filter
(also: provide protection
from outside dust)
Schmidt corrector ring
Camera with 440 PMTs
(Photonis XP 3062)
•cloud monitors at each eye
• central laser facility
• regular balloon flightsAtmospheric Monitoring
steerable LIDAR facilities
located at each FD eye
Central laser facility (fiber linked to tank)
LIDAR at each FD building
Balloon probes (T,p)-profiles
40 MHz FADC,
local triggers, 10 Watts
Plastic tank with
12 tons of water
Assembly building, yard