Post on 06-Jan-2016
description
Pierre Auger Observatory
Outline• Cosmic Rays• Pierre Auger Observatory
▫ Description/Status▫ Enhancements▫ Future
• Auger Results• Auger @ LIP
▫ Detector Simulation▫ Measurements ▫ Phenomenology
• Conclusions
M. Pato, P. Assis, P. Brogueira, P. Abreu , P. Gonçalves, B. Tomé, J.
Romão, R. Conceição, M. Pimenta, S.
Andringa, E. Santos, M. C. Espírito Santo, J. Dias de Deus, J. G. Milhano
Ultra-High Energy Cosmic Rays• Cosmic rays with E > 1020
eV arrive on Earth at the rate of 1 particle per km2 per century
• Their composition and their sources are unknown
• Create a shower of particles when they enter the atmosphere▫ Hadronic▫ Electromagnetic
• Can be detected▫ Ground Arrays▫ Fluorescence Detector
Moonless nights
Pierre Auger Observatory• The Auger Observatory is a
"hybrid detector," employing two independent methods to detect and study high-energy cosmic rays:
• Surface detector (SD)▫ 3000 km2 in the Pampa Argentina▫ 1600 pure water tanks▫ 1.5 km spacing
• Flourescence Detector (FD)▫ 4 “eyes”▫ 6 telescopes in each viewing 30º x
30º▫ 4 weather stations (with LIDARs)▫ 2 Laser Facilities
FD
SD20 May 2007 E ~ 1019 eV
Event ReconstructionSurface Detector Fluorescence Detector
• Tank hit time gives shower direction
• Energy is obtained using Nch( distance to the
shower core )
• Evolution in camera gives the shower geometry
• Energy is calculated by integrating a universal longitudinal profile
Hybrid Technique
• Better reconstruction geometry▫ Higher Xmax resolution▫ Better energy
reconstruction
• Calibration of SD with FD▫ Reduce systematics▫ Good correlation between
SD and FD
SD
FD
Auger EnhancementsAMIGA HEAT
• Auger Muons and Infill for the Ground Array
• Study muon component of showers▫ Good variable to check
hadronic models
• – Hexagon (7 x 60 m2)• 2 – Infill array 433m• 3 – Existing tank array 1500m• 4 – Infill array 750m
• High Elevation Auger Telescopes• 3 “standard” Auger telescopes
tilted to cover 30 - 60° elevation
Extend studies to lower energies ~ 1017 eV
FutureAuger North Auger South Extension
▫ Construction 2009-2012 ?
▫ Total area: 20 000 km2
▫ About 7 x Auger South extension 4032 surface detectors
3 FD eyes
• Expansion possibilities for Auger South If a non-compact configuration is acceptable▫ 60 000 km2 ??
• Many possible Upgrades▫ Radio Antenna Array▫ …
1 Linsley = 1 L = 1 km2 sr yr
• Energy Spectrum• Anisotropies• Xmax
Energy Spectrum
• GZK cut-off▫ Interaction
with CMB photons degrades energy
• Ankle▫ Transition from galactic to extra-
galactic sources?
AnisotropiesSearch for Sources ( E > 57 EeV ) positions of (318 visible+164invisible) AGNs at z < 0.018 (D< 75 MPc)
19 out of 27 events are within 3.1º of an AGN !!( The probability of having an isotropic distributions is 10-5 )
Evidence for Proton Primary?
The angular aperture suggests that the particle is a proton!
EnergyE > 57 EeV
Angular aperture
α = 3.1
Distancez < 0.018 → D < 75 MPc
Low EHigh Z
High ELow Z
Xmax – Primary Composition
• Iron showers develop faster than proton
• Slope depends strongly on the interaction models
• Auger data indicates heavier
composition at high energy!!!!!
Particle Physics?!...Particle Physics?!...
• Good understand of the detector• Geant 4 Simulation of the FD• Simulation studies for AMIGA
• New variables from data• 3D Analysis• Čerenkov
•Phenomenological Models
Particle Physics @ Cosmic Rays
FD Simulation with Geant 4
Going into detail...
Geant 4 Simulation
• Good overall agreement with official simulation
• Small differences with some more realistic settings▫ Good tool to find systematics!!
Mirror curvature from database!!
New possibilities…
Simulation studies for AMIGA
•Muon selection effieciencies of 80 to 90%•About 10% of multihits
3D Reconstruction Method• Currently for FD the shower is
being treated as a 1D object but it’s an 3D object
• It is possible to get information about the “width” of the shower taking the arrival time of photons at the detector into account▫ It uses time as a 3rd dimension
Adding Time
3D Reconstruction Method
• This method obtains a good agreement with the simulation
• Longitudinal Profile
• Lateral Profile
• Low statistics
Simulation
Longitudinal Profile
Lateral Profile
Ratio Expected / Observed
3D Reconstruction Method
• 6 Months of data
• Longitudinal Profile shows a good agreement
• Lateral Profile shows a clear disagreement
•Data seems wider
• Detector?• Physics??
Experimental Data
Ratio Expected / Observed
Longitudinal Profile
Lateral Profile
3D Simulation• Currently:
▫ Čerenkov and fluorescence photons are produced from longitudinal profiles (1D)
▫ All photons are propagated to the lens and then spread transversally
• A 3D Reconstruction needs a 3D Simulation!
Auger Simulation and Reconstruction Software
(Offline) with some modifications
3D SimulationAlready a first shower…
Čerenkov
• Shower produce intense colimated beam
• Events with a large fraction of Čerenkov light are interesting because they allow us to:▫ See further away ▫ Improve horizontal ν
search▫ Study Čerenkov
properties A(α) – Lateral
Distribution Function of Čerenkov
FD
Showeraxis
Extensive Air Shower (EAS) Physics • Phenomenological
Approach• Extrapolate from
accelerator energies to several orders of magnitude above
Exploring High Energy Hadronic Models…
Models
New models and possible high energy effects…
String Percolation
• As energy increases the number of sea strings increases
• Strings overlap and fuse creating more energetic strings with higher length in rapidity▫ Create faster particles▫ Change the type of the
leading particle• In EAS:
▫ Change number of muons▫ Change the Xmax
But how important are valence quarks??
Net-Baryon ( Simple Model )• Net-Baryon is • Two step-scenario Model
▫ String Formation Valence quarks Energy obtained from
PDFs Parameter Q2 (√s)
▫ String Fragmentation String decays into a
meson and a baryon Kinematic Constraints
Net-Baryon Results• Usual Models have problems
explaining the data• Effective Q2 obtained from fit
to data• Evolution with energy is a
consequence of QCD evolution of the PDFs and the kinematic constraints in the string fragmentation
• Simple model can reproduce Net-Baryon main features
• Our model shows that the role of the Net-Baryon is not negligible
Conclusions
•Auger opens new windows in:▫Astrophysics▫Particle Physics
•The LIP group has an active and enthusiastic participation!!
A little bonus…