High Energy Cosmic Rays and the Pierre Auger Observatory
Transcript of High Energy Cosmic Rays and the Pierre Auger Observatory
High Energy Cosmic Rays and
the Pierre Auger Observatory
Sofia AndringaLIPLisboa
CFTC, 21st February 2007
High Energy Cosmic Rays and
the Pierre Auger Observatory1. Cosmic Rays, Particle Physics and Astrophysics2. Atmosphere as a Detector3. Experiments: HiRes and AGASA and
The Pierre Auger Observatory4. Auger's First Results and Prospects5. Auger at LIP
High Energy Cosmic Rays Flux(m2.sr. s.GeV)1
Energy(eV)
1 particle per km2.century
1 particle per m2.s
1 particle per m2.year
1 particle per km2.year
High Energy Cosmic Rays Flux(m2.sr. s.GeV)1
E(eV)
1 particle per km2.century: “toe?” GZK limit
1 particle per m2.s
1 particle per m2.year:
“knee”limit for SNR
1 particle per km2.year:“ankle”
Galactic / Extragalactic
Flux*E2.5
Flux*E3Flux*E3
Flux
Cosmic Rays and Particle Physics
different techniques:only 20 events above
1020 eV
The largest accelerator!
Cosmic Rays and Astrophysics
Production: sources, spectra, composition, acceleration mechanismsPropagation: magnetic fields, interactions with medium, solar wind
... magnetosphere, atmosphere...
Cosmic Rays and Astrophysics
Emax
=ZBL
available energies at sources,energy losses during way...and deflections...
new astronomy channel for very high energies: can look for sources!
GreisenZatsepinKuzmin (GZK) cutoff
p
(2.7K)
= p
CMB
~ 6 Mpc for E~1020eVno known sources so close!
Cutoff or pileup:depending on source types and source distributions,primary compositions,magnetic fields....
Cosmic Rays and Astrophysics
E>1014 eV>Extensive Air Shower in Atmosphere
high energy nuclear interaction in > km to multiply particles > 1 hadron: 100 muons: 10000 e/e+/huge number of particles over some km2
High Energy Cosmic Rays
Nemax E
Xmax
lnE
Energy and particle types? light or heavy ions?horizontal , double bang , LQ, BH, ?
high energy interactions: extrapolated QCD...+ other (new) interactions? [info from LHC?] different fragmentation models?check by comparing EM to Hadronic...
low energy interactions: from accelerator meas.+ details of atmosphere, lots of simulation...check by comparing different particle types and spatial distributions
look at general trends (sources, energy spectra, composition) but also details of “normal” data to isolate unexpected
High Energy Cosmic Rays
High Energy Cosmic Raysas Extensive Air Showers
To see very few, very energetic particles we need big detectors: Atmosphere
Particles at ground Cerenkov Radiation Radio emission Fluorescence light ...
Different techniques relying on different properties and
interactions
Extensive Air Showers Surface Detectors:thousands of particles reach the ground,spreading over several km2...
core and arrival times give the axis line.
Energy from density of particles at a given distance from the core. Composition statistically by densitiesof different particles...
AGASA
parameterizedby simulation
Extensive Air Showers in Cerenkov Particles with v > c' (in medium) emit Cerenkov light in a 1o2o cone in air (reaching 20o due to p
T).
Cerenkov Radiation from EAS can be 0.01% of all night sky lightseen only in clear moonless nights > 10% duty cycle
directionality: allows to point at sourcesto check high energy gamma emissionfrom known sources and find structure
SNR seen by Magic+VLA radio+Gas clouds
Extensive Air Showers in Radio
Annihilatione+
eγ
Compton
e
e1. The shower has a negative net charge (~10% excess)
2. The geomagnetic field separates e+ from e
two charged currents and also dipole emission
better even for horizontal showers: neutrinos
e
e+ coherent emission at wavelengths > typical dimensionsvery good directionality but high backgrounds?
Extensive Air Showers Fluorescence Detectors:Atmosphere as electromagnetic calorimeter
electrons excite N2 molecules which emit
isotropic UV light.
As much as Cerenkov light but isotropic!nondirectionality allows for cosmic rays to be detected in a large volumein clear moonless nights: 10% dutycycle
Shower axis line reconstructed fromtelescope granularity, stereo observations and time dependence.
Energy found from the EM part of theshower. Composition given statistically by analysis of the shower longitudinal profiles.
Nemax E
Xmax
lnE
HiRes Fly's Eye
The Pierre Auger Observatory “Observatory” for Particle Physics also: available E ~ 1100 LHCsRelatively high luminosity: 1/century/km2 ~30/year/Auger
Hybrid detector:
use the best of each technique
confirm energy reconstruction
understand interactions
The Pierre Auger Observatory: SD
1600 pure water tanks1.5 km spacing 10 m2 eachinstallation will end in 2007
3000 km2
in the Pampa Argentina
The Pierre Auger Observatory: SD Water Cerenkov detector: 70% muons + 30% electrons
reconstruction from E and T
Autonomous systems:
solar panels and batteries,Radio communications,GPS timing,40 MHz FADC
The Pierre Auger Observatory: FD 4 “eyes” (3 working already)6 telescopes in each viewing 30ox30o
with 440 pixel cameras... and 4 weather stations!
The Pierre Auger Observatory: FD emitted Fluorescence light depending on p,T,(new measurements is 2006!)and attenuated due to clouds and also Rayleigh and Mie scattering
+ not perfect optics: a dot is a spot...
I=I01+cos2
2R22
n21n2+2
d2( ( ( )))4 2 6
> signal loss and distortions,mainly for low altitude(higher density and dust)
Pierre Auger Observatory: Extensions
Galactic
Center
Auger North (2009?): 10.000 km2
larger spacing1 or 2 big eyeshigh energyextragalactic sources
0o 30o
30o 60o
1.5 km0.75 km
Auger South (20078): + galactic sourceslow energy extension smaller spacing SD higher angle FD other techniques(Radio, etc)
Pierre Auger ObservatoryThe standard FD reconstruction1. plane that contains pixel directions(SDP: showerdetector plane)
2. fit central time vs. projection in SDP(shower axis and core)
> better if SD times can be used!
3. fit energy along this line assumingGaisserHillas distribution(works well for regular p/Fe showerswith maximum inside detection volume)
FluorescenceDetection:EM shower
Surface Detection:Hadronic shower(and muons)
SD vs FD
The Pierre Auger Observatory
Old Energy Spectras
Different spectras from different techniques?Calorimetery in Atmosphere vs. Simulation results: systematics?
HiRes (FD) AGASA (SD)
Air Showers SimulationsSurface Detection depends on Simulations:
* unkown highenergy interactions?* low pT accelerator measurements extrapolated to energies many orders of magnitude higher* hard, soft, diffractive collisions...* many models...
many particles...follow onlysubshowers
Atmosphere MonitoringFluorescence detection depends on the description of the atmosphere and its changes inpressure, temperature +the presence of clouds(monitored constantly), but also dust, etc...
winter / summer @ Malargue
New Energy SpectraAlthough only 10% of the events are hybrid we can calibrate theenergy from Fluorescence and rely on simulation for missing energy only.
Use SD reconstructionS1000 (density 1000 m from core)
S38 (what it would be at 38o)
Energy Calibrated by FD
Spectrum with high statistics and (almost) no simulation of air showers
New Energy Spectra (Aug. 2005)Still no events above 1020 eV...
(only 1st Auger spectra:~6 months of full Auger~full AGASA exposure)<25% systematics fromcalibration aerosols and cloudsfluorescence yieldmissing energy correction
new results for ICRC 2007:with 45x AGASA/HiResand (much) lower systematics
Search for sources? Known or Suspect SourcesCorrelations with catalogs? > need low number and
good directionality
Unknown or Surprise SourcesAutocorrelations in data? > need high statistics and
good directionality
Cosmic Ray arrival directions seem very isotropic.Possibly not so at high energy?Directionality depends on energy!
Search for sources? AGASA
4.5
E > 4 1019 eV5 pairs and 1 triplet within 3o
* expected onesor
* surprises
Old results forAGASA high energyevents.
Not seen by Auger: *need more statistics...
Primary Composition
Composition measurements always based on MC...Can confirm models?
proton
iron
AGASA
muons from hadronic interactions
Primary Composition
Change of sources? Change of methods?
Large differencesin simulation models:
other ways to measure?* mostly dispersions
Pierre Auger Observatoryactivities at LIP
* detailed simulation of the telescopes
* detailed simulation of the Rayleigh and Mie Scattering
* hadronic physics and new physics models
* FD reconstruction measurement of the Cerenkov contributions
3D reconstruction and fluorescence lateral profiles
Scattering SimulationSimulate atmosphere,Rayleigh Scattering and Mie Scattering
allows to study Auger Lasers!
> for atmosphere monitoring,scattering correction studies,alignment tests, spot and camera tests
Hadronic Models
Towards a full modelsimulation:
test effects on:inelasticity, pT,> and oncomposition analysis!
J.Dias de Deus et al
Percolation?
Many different models, mostly empirical:understand details of interactions and effects on observables
CerenkovCerenkov radiation is seen when the shower approaches the eye!Much more intense than Fluorescence, at specific angles (up to 20o due to pT)
It is a background – regarding the FD calorimetry but can give information on pT distribution within shower!
3D reconstruction
Assuming planar wave propagationto find a unique 3D volume[position along axis line+transversal coordinate]
T emission+ T prop.
Try recover one more dimensionwith more information from time
FD reconstructs shower as a 2D line
3D view of a closeby Cosmic Ray each point/volume has different precision in space.
Energy isdistributed in volumes
Can be used for fittingand to searchfor structures.
3D reconstruction
3D view of a cloud The points more compatible with a line are shown. Large energy loss in the cloud...
3D reconstruction
Z
XY
New variables: average radius, symmetry,...analysis starting in data (and simulations)
R (in km)
shape var.
3D analysis
Direct access to transverse profile of shower:good to test pT, electromagnetic shower developmentand help in determination of Xmax (composition)direct integration of the energy in true geometry!
3D analysis and New Physics?
τ
BH
Horizontal showers are a signature for neutrinos...
... double bang showers can be a signature for taus > also nonhadronic physics in Auger:
Searches for Black Holes,Excited Leptons, Leptoquarks, ...
S.Bottai
quasi horizontal
Earthskimming
Up –going (with regeneration)
SummaryUltra High Energy Cosmic Rays:
many mysteries to be solved new scales in Astrophysics and Particle Physics
The Pierre Auger Observatory:profit from Hybrid measurements already some results, many more this year, maybe some surprises...South almost completed, to be extended, North will come soon
LIP:entered Auger in March 2006~10 people, lots of work, many ideasmore ideas and help welcome!