Results from the Pierre Auger Results from the Pierre Auger
Observatory Observatory
Universit
Università à del Salento e INFN Lecce (Italy) del Salento e INFN Lecce (Italy)
Lorenzo Perrone for the Pierre Auger Collaboration
Lorenzo Perrone for the Pierre Auger Collaboration
Outline Outline
• Physics goals and operation range Physics goals and operation range
• Detector description Detector description
Performance and observables
Performance and observables
• Results Results
• Enhancements and incoming Enhancements and incoming achievements
achievements
The Pierre Auger Observatory: range of operation The Pierre Auger Observatory: range of operation
Auger
ENHC
Study of the transition between galactic and extra- galactic cosmic rays
- Ankle region
- 2nd Knee region (with lower energies extensions )
Energy spectrum Arrival directions Composition
Search for photon and neutrinos as primary cosmic rays
Hadronic physics
End of the spectrum (GZK
region)
Ankle
GZK
Particle Data Group
The physics case The physics case
2nd Knee
EGalExtraGal ~ 1017.5 eV Dip Model
Extragal. protons (Berezinsky et al.)
EGalExtraGal ~ 3 1018 eV Mixed comp. of
extragal. component (Allard et al.)
EGalExtraGal ~ 1019 eV Extragal. protons (ankle model)
“ “ the ankle”: models and hyphoteses the ankle”: models and hyphoteses
M.Unger, arXiv:0812.2763 [astroph]
6
Greisen Zatsepin Kuz'min effect (1966):
Interaction with the cosmic microwave background (CMB)
nuclei: photodisintegration and
pair production on CMB (RB IR)
photons:
protons:
End to the cosmic ray spectrum?
End to the cosmic ray spectrum?
“horizon” (p and nuclei) ~ 100 Mpc ( ~1020 eV )
Surface detector
an array of 1600 Cherenkov stations on a 1.5 km
hexagonal grid (~ 3000 km2)
Fluorescence detector
4 buildings overlooking the array
The Pierre Auger Observatory The Pierre Auger Observatory
~ 60 km
Low energy extensions
AMIGA: dense array plus muon detectors
HEAT: three further high elevation FD telescopes
The Hybrid Concept The Hybrid Concept
accurate energy and direction measurement
mass composition studies in a complementary way
Surface Detector Array
lateral distribution, 100% duty cycle
Air Fluorescence Detectors
Longitudinal profile, calorimetric energy measurement, ~15% duty cycle
““In order to make further progress, particularly in the field of cosmic In order to make further progress, particularly in the field of cosmic rays, it will be necessary to apply all our resources and apparatus rays, it will be necessary to apply all our resources and apparatus simultaneously and side-by-side.”
simultaneously and side-by-side.” V.H.Hess, Nobel Lecture, December 1936V.H.Hess, Nobel Lecture, December 1936
A station of the Surface Detector A station of the Surface Detector
•
Plastic Tank• Ultrareflective tyvek liner
• 12 m3 purified water
• 3 PMTs (9 inches)
• Independent power supply (solar panels) s
• GPS antenna
• Communication antenna
D
6 telescopes, each with 30° x 30° FOV
30°
30°
The fluorescence detector (FD)
The fluorescence detector (FD)
Spherical mirror cameraPMT
Diaphragm
UV Filter Shutter
Camera: 440 PMTs
Aperture of the pixels: 1.5°
The fluorescence detector (FD)
The fluorescence detector (FD)
Observables and Detector Observables and Detector
Performance Performance
• Reconstruction of arrival directions with Reconstruction of arrival directions with FD/SD/Hybrid
FD/SD/Hybrid
• Reconstruction of longitudinal profile Reconstruction of longitudinal profile
• Energy determination Energy determination
FD-Hybrid geometry reconstruction FD-Hybrid geometry reconstruction
SDPSDP
ShowerDetector Plane (SDP) using the directions of the triggered pixels
Shower axis from the timesequence of triggered FD pixels plus the information from
Time Fit Time Fit
FD-Hybrid geometry reconstruction FD-Hybrid geometry reconstruction
SDPSDP
ShowerDetector Plane (SDP) using the directions of the triggered pixels
Shower axis from the timesequence of triggered FD pixels plus the information from the “hottest” SD station
Time Fit Time Fit
monocular hybrid
N
γ( ) λ
R
iA T( ) λ
E
depPhotons at diaphragm
E
depN
γ( ) λ
Photons inFD FOV ADC counts
Fluorescence yield (from laboratory measurements)
Detector calibration Geometry
A
AtmosphereT( ) λ
FD: energy determination FD: energy determination
Longitudinal Profile Longitudinal Profile
Energy “Calorimetric measurement”
dXdX Eem =∫ dE
XmaxXmax
Energy estimator: S(1000)
particle density at 1000 m from shower axis Direction:
fit to arrival times sequence of particles in shower front
SD reconstruction SD reconstruction
Systematic uncertainties on energy determination
30% from hadronic interaction models at high energy
1020% from hadronic interaction model at low energy
~50 km
E E ~ 10~ 101919 eV eV 4 FD eyes 4 FD eyes 15 stations 15 stations
Event topologies
Event topologies
• Energy spectrum
• Mass composition
• Astrophysics
• Search for photons and neutrinos
• Hadronic interactions
Results
Results
+ Full efficiency at 1018 eV (ankle region) + Calorimetric measurement
+ Energy Resolution of 8%
Limited duty cycle (~13%)
Time and Energy dependent Exposure MC based, influenced by the atmosphere, DAQ and detector configurations
Clear indication of the ankle
Hybrid Spectrum Hybrid Spectrum
Data: Nov. 2005 – Sept. 2010
Systematic uncertainty on exposure 10% (6%) E ~ 1018 eV (>1019 eV)
Energy calibration Energy calibration
Using hybrid events, the SD energy estimator is calibrated without relying on Monte Carlo 7.5 1019 eV
E
FD=AS
38BB~1
Method Systematic Uncertainties
15% a 1020 eV 7% a 1019 eV
Jan 2004 – Sept 2010 E > 3 EeV zenith < 60°
S38 > S1000 that a shower would have produced had it arrived with a zenith angle of 38°
R.Pesce @ ICRC 2011 839 hybrid events
F.Salamida @ ICRC 2011
SD Energy spectrum SD Energy spectrum
Flux suppression > 20
Flux suppression > 20 σσ
E> 3 EeV and zenith < 60°
20905 km2 sr yr (Jan 04 Dec 10)
geometrical, counting active
hexagons. Not relying on simulations, full efficiency
independent of primary mass
3% systematic uncertainty
64000 (5000) events E > 3 1018 eV (> 1019 eV)
Energy resolution ~ 15%
forward folding method to correct for the bintobin migration
SD Exposure
Total systematic uncertainty on flux ~ 6%
22% on the energy scale
Inclined events and E > 4 EeV Inclined events and E > 4 EeV
Energy estimator:
N19 > lateral muon density
H.Dembinski @ ICRC 2011
Jan 04 – Dec 10
Full agreement with
flux from vertical showers
62° < Zenith< 80°
Energy Calibration with FD energy
The Auger Energy spectrum
The Auger Energy spectrum
• Energy spectrum
• Mass composition
• Astrophysics
• Search for photons and neutrinos
• Hadronic interactions
Results
Results
Observation of longitudinal profile Observation of longitudinal profile
Auger
<
max> = (ln E <ln A>)+
<Xmax> and its RMS
sensitive to mass composition
Mass Composition: mean X
Mass Composition: mean X
maxmaxand its RMS and its RMS
G. Pinto @ ICRC 2011
→ interpretation depends on hadronic interaction models
→ increase of the mean mass with the energy
6744 hybrid events (Dec 2004 – Sept 2010) E > 1018 eV
80% more events w.r.t PRL 104 (2010) 091101 consistent results Syst uncertainty <
Syst uncertainty < 13 g/cm2 13 g/cm2 Xmax resolution ~ 20 g cmXmax resolution ~ 20 g cm22
Mass Composition: X
Mass Composition: X
max maxDa completare
Courtesy of Michal Unger
none of the model satisfactory explains data yet (shape, absolute value)
→ constraints by studying X
maxdistribution (known syst. unc.)
Data compared to models
Data compared to models
Energy spectrum
Mass composition
Astrophysics
Search for photons and neutrinos
Hadronic Interactions
Results
Results
30
Astropart. Phys. 34 (2010) 314
The 69 events with Energy > 55 EeV detected by the Pierre Auger Observatory
Blue circles of radius 3.1° centered at the positions of the 318 AGNs < 75 Mpc in the VCV catalog. The exposureweighted fraction of the sky covered by the blue circles is 21%
(fraction of correlating events under the hypothesis of isotropy)
Anisotropy at the highest energy Anisotropy at the highest energy
Limitations of the catalogue: incomplete and inhomogeneous
Centaurus A Centaurus A
Jan 2004 Dec 2009
31
Degree of correlation Degree of correlation
Astropart. Phys. 34 (2010) 314
Degree of correlation p_data = k/N vs total number of timeordered events:
the 68%, 95% and 99.7% confidence level intervals around the most likely value are shaded.
The isotropic value is p_iso = 0.21. The current estimate of the signal is 0.38 (+0.07, 0.06).
k/N = 0.38
32
5detection requires more data (165 for P=6*10
7)
→ tests on other catalogues: 2MRS (IR) & SwiftBAT (Xrays)
A posteriori searches A posteriori searches
Astropart. Phys. 34 (2010) 314
2MRS SwiftBAT
33
Centaurus A Centaurus A
CEN A: optical image, radio contours (VLA), VHE best fit position and 95% C.L. (HESS).
From http://arxiv.org/pdf/0903.1582v1
Cumulative number of events with energy E>=55 EeV as a function of angular distance from the direction of Cen A.
The bands correspond to the 68%, 95%, and 99.7% dispersion expected for an isotropic flux. 13 events fall in this area (18°) vs. 3.2 expected from isotropic flux.
Astropart. Phys. 34 (2010) 314
Anisotropy and chemical composition Anisotropy and chemical composition
Z=26 Z=13 Z=6
If the excess at Ethres > 55 EeV is due to nuclei (Z), the proton counterpart should be observed at energy above Ethres/Z
The Pierre Auger Collaboration, JCAP06 (2011) 022
Lemoine & Waxman JCAP 11 (2009) 009
No excess observed from CEN A at lower energies
Upper limit to the proton fraction at the source
(within the model assumption)
Spectral index at source
f.a.q. since November 2007 f.a.q. since November 2007
What do data say up to now?
f.g.a
f.g.a: Data show a correlation with the local distribution of matter within a few hundred of Mpc and are inconsistent with the expectation from an isotropic distribution
Open Issue:
Anisotropy consistent with a proton based composition Xmax measurement suggest mixed composition
Anisotropy not confirmed by HiRes (northern Hemisphere)
Astroparticle Phys. 30 (2008) 175
• Energy spectrum
• Mass composition
• Astrophysics
• Search for photons and neutrinos
• Hadronic Interactions
Results
Results
Search for photon primaries Search for photon primaries
Photon showers develop deeper in the atmosphere
Deeper Deeper
showers larger showers larger curvature
curvature
Slower signal, Slower signal, longer risetime longer risetime
FD: search for events with deep Xmax FD: search for events with deep Xmax
SD: search based on signal time structure SD: search based on signal time structure
(hybrid) photon/hadron separation (hybrid) photon/hadron separation
Hybrid Exposure for photons
deep shower
large Xmax (from FD)
structure of the LDF
different time structure and smaller signal (from SD)
ignal amplitude
Realistic and time dependent
actual DAQ and atmospheric conditions taken into account (same approach used for the hybrid spectrum)
Proton background less than 1%
simulations
favour astrophysical origin of UHECR
reduce systematics in measurements of energy spectrum, pair cross section, mass composition
m
Upper limits to the integral photon fraction assuming the Auger Spectrum
0.4%, 0.5%, 1.0%, 2.6% and 8.9% for E> 1, 2, 3, 5 and 10 EeV
Number of candidates
GZK region within reach
Upper limit to the integral photon flux Upper limit to the integral photon flux
topdown models
severely constrained
flux and fraction upper limits down to the EeV region
M. Settimo @ ICRC 2011
See M. Monasor at this
Search for neutrinos Search for neutrinos
ear th at m os phe
re
Almost verticalmuons + electromagnetic
Very inclined, thin flat front high energy muons
3µs
0.3µs
Important for neutrino detection: observable only if almost horizontal
Neutrino signature: an inclined shower with large electromagnetic
component
Neutrino-like event selection Neutrino-like event selection
DataData
Simulated Simulated
neutrino signal neutrino signal
Length/width >5 Length/width >5
0.29< speed < 0.31 m/ns 0.29< speed < 0.31 m/ns
Earthskimming Earthskimming
Upper limit on the diffuse neutrino flux
Upper limit on the diffuse neutrino flux
Upper limit on integral neutrino flux from CEN A
Upper limit on integral neutrino flux from CEN A
Energy spectrum
Mass composition
Astrophysics
Search for photons and neutrinos
Hadronic Interactions
Results
Results
Measurement of the p-air cross-section Measurement of the p-air cross-section
Tail of the distribution of <Xmax> sensitive to crosssection
Ellsworth et al. Phys. Rev. D26 (1982) 336
Baltrusaitis et al. Phys. Rev. Lett. 52 (1984) 1380
18< log10(E/eV)< 18.5
Use simulations to correlate
f
MC with crosssections
Dedicated analysis to select a protonenriched data sample
dominated by protons
fMC adjusted to reproduce the measured f
20%
Why 20%?
15% helium contamination produces a bias at the level of the statistical uncertainties Fly's Eye
Energy well above the LHC measurements
ICRC11 Auger Systematic Uncertainties
hadronic models
energy scale
simulations
Total: 15 mb, +20 mb
Additional Uncertainties due to diverse contaminations:
photon fraction 0.5% +10 mb
helium fraction 10% 12 mb
helium fraction 25% 30 mb
Enhancements and future plans Enhancements and future plans
The Pierre Auger Observatory as an ideal site to test alternative measurement techniques
Extension towards the lower energies
• improve detector performance at the transition to extragalactic component between ~10
17and 10
18eV (HEAT and AMIGA)
• cross calibration with other experiments
• Radio detection (AERA)
• Microwave detection (several projects)
Taking data since Sept. 2009 3 telescopes nearby Coihueco 30° up to 60° elevation
FD Auger enhancement: HEAT FD Auger enhancement: HEAT
E~1.7 1017 eV
Higher elevation
lower energies (~ 1017 eV) unbiased observation of longitudinal profile
Energy reconstruction
crosscalibration of HEAT (working in downward mode) and Coihueco
agreement with simulations
First data used for alignment and calibration
Plenty of new highquality data are being collected
SD Auger enhancement: AMIGA SD Auger enhancement: AMIGA
53 station with spacing 750 m deployed
4 buried scintillator modules installed
INFILL array (Cherenkov stations) and Muon detectors (scintillators)
Exposure: (26.4 ± 1.3) km2 sr yr
E
thres~ 1 GeV
S(450)
Imminent result:
the energy spectrum down to 3 1017 eV S(450) > particle density at 450 m
S35 corrected for the zenith angle dependence
22% (13%) uncertainty at 3 (10 )VEM
About 200.000 fiducial events collected Full Efficiency above 3 1017 eV zenith < 55°
Angular resolution 1.3° (1°) for at least four (six) stations
Infill array performance
Infill array performance
AERA: Radio detection AERA: Radio detection
Ethres ~ 1017 eV
First physical radiohybrid events (Radio+SD) First RadioFDSD super hybrid event
(April 2010, being analyzed )
Polar plot, SD and radio reconstruction
• Deployed in 2010
(21 Radio stations, 150m)
▴ stage 2 (250 m) + stage 3 (350 m)
3 km to Coihueco ~ 20 km2
VHF band 10100 MHz
Microwave detection
Microwave detection
Conclusions
Conclusions
Back-up slides
Back-up slides
Conclusions Conclusions
The Pierre Auger Observatory (south site) takes data smoothly since 2004 First results extremely encouraging
Energy spectrum
Energy spectrum
Flux suppression at E>4 1019 eV observed (conf. by HiRes) hints on imminent updated results for hybrid spectrum
Composition
Composition
Arrival directions
Arrival directions
Search for neutrino and photons Search for neutrino and photons
new limits to photon fraction in EeV range
New results with higher statistics are imminent (ICRC09)
Enhancements (HEAT, AMIGA) will allow covering lower energies The northern site will provide full sky coverage and larger acceptance
Comparison with other incoming projects (TA) will help clarifying open issues
Auger north Auger north
Site: Colorado, Lamar
Atmospheric profiles Atmospheric profiles
Malargue monthly models
Local measurements with:
•radio soundes
•ground based
weather stations
Infrared cloud monitoring Infrared cloud monitoring
Los Leones
Coihueco
Full sky cloud scan Finely pixelated
infrared camera
1 per eye
Aereosol monitoring Aereosol monitoring
• Aerosols: clouds, dust, smoke and other pollutants
Backscatter Lidars
Backscattered light
r
• 1 steerable laser per eye
• hourly scan of aerosols and “shoot the shower”
Cloud image
VAOD = Vertical Aerosol Optical Depth
~30 km
T ~ e
VAODExpected laser profile without aerosol
Central Laser Facility
Central Laser Facility
Si e’ cercata una correlazione degli eventi di alta energia rivelati da Auger con AGN raccolte nel catalogo VeronCetty and Veron.
La ricerca si e’ fatta variando tre parametri: Energia, apertura angolare e redshift (distanza) e confrontandosi con l’ipotesi di distribuzione isotropa
Sorgenti di raggi cosmici
Sorgenti di raggi cosmici
Utilizzando i dati raccolti dal 01/01/2004 al 27/5/2006 (dati disponibili al momento dell’analisi) si sono identificate le condizioni che
rendevano minima la probabilità che gli eventi rivelati provenissero da una distribuzione isotropa.
Con E>57 EeV Distanza angolare 3.1° e Dmax=75 Mpc, si identificavano 15 eventi di altissima energia di cui 12 correlati con AGN “vicini”
contro un numero atteso, in caso di distribuzione isotropa, di 3.2.
(p~10-3)
Parte una “running prescription”. Si definiscono le condizioni per escludere al 99% l’ipotesi del flusso isotropo con eventi raccolti dopo il 27/5/2006 e
ricostruiti nelle stesse condizioni
4 6 8 10 12 …
4 5 6 7 8
25/5/2007 condizione soddisfatta!
4 6 8 10 12 …
4 5 6 7 8
Sorgenti di raggi cosmici
Sorgenti di raggi cosmici
Hybrid Exposure
Hybrid Exposure at the tightest selection level
Hybrid Spectrum
Only statistical uncertainties given
Good agreement found within the systematic uncertainties
Hybrid vs SD Spectrum
1.5 km
1.5 km 1.5 km
1.5 km
Last tank (13/6/2008) Last tank (13/6/2008)
The surface detector (SD)
The surface detector (SD)
Direction:
fit to arrival times sequence of particles in shower front
Energy:
Reconstruction of lateral profile and use of Monte Carlo
simulations to derive the energy
SD reconstruction
SD reconstruction
Energy estimator:
particle density at 1000 m from core S(1000) S(1000) is proportional to
the energy of primary particle and weakly dependent on primary type
Systematic uncertainties
30% from hadronic interaction models at high energy
1020% from hadronic interaction model at low energy
Reconstruction of lateral Reconstruction of lateral
profile profile
Core Distance [m]
Observation of longitudinal profile Observation of longitudinal profile
Only events with Xmax in FOV independently of primary type are accepted (no bias)
Auger
Syst uncertainty <
Syst uncertainty < 15 g/cm2 15 g/cm2 Xmax resolution ~
Xmax resolution ~ 20 g/cm2 20 g/cm2 XmaxXmax
FD-SD-Hybrid FD-SD-Hybrid
SDonly FDonly Hybrid
Dutycycle ~100% (high stat) ~1015% ~1015%
Anguar Res. 12 deg ~3 deg ~ 0.5 deg (>1 EeV) Energy relies on MC missing energy missing energy
and composition geometry bias
Acceptance independent of MC dependent on E, MC dependent on energy and and composition E, MC e comp.
composition
Energy Range ~>1018.5 eV ~>1017,5 eV ~>1018 eV
Astrophysical implications Astrophysical implications
LogELogEankleankle = 18.65 ± 0.04 = 18.65 ± 0.04 LogEc = 19.74
LogEc = 19.74 ± 0.06± 0.06 Wc = 0.16 ± 0.04 Wc = 0.16 ± 0.04
γ 1=3.30±0.
06
γ 2=2.56±0.
06
Caviglia
E=1019eV
Xmax as indicator of mass Xmax as indicator of mass
composition composition
Proton
Proton IronIron
Atmospheric depth of shower maximum correlated with primary type (Example: proton showers develop deeper than iron , Xmax,pr >
Xmax,Fe)
http://wwwik.fzk.de/corsika
Proton Iron
Xmax,Fe ~ 700 g/cm2 Xmax,p ~ 800 g/cm2
A stereo hybrid event A stereo hybrid event
Evento: 1364365
lg(E/eV)~19.3
(θ , φ ) = (63.7°,148.3°)
lg(E/eV)~19.2
(θ , φ ) = (63.7°,148.4°)
17 stazioni lg(E/eV)~19.1 (θ , φ ) = (63.3°,148.9°)
SD array
larger hybrid events sample
reconstruction quality cuts fiducial volume cuts
cloud coverage correction
powerful statistical method
Xmax as discrimination variable and cut at median of
MC photon distribution
MC photon
DATA E>10 EeV
First limit
First limit on photon fraction in EeV on photon fraction in EeV range
range
detector efficiency study
detailed detector simulation
(CORSIKA, FLUKA, QGSJET01) (
different inducing primaries
(iron proton photon) )
relative acceptance correction conservative approach
First limit
First limit on photon fraction in EeV on photon fraction in EeV range
range
Composition studies with air showers Composition studies with air showers
hadrons
~ 58 gcm2 /decade
d<
max>
dLog(E)
sensitive to primary mass key observable for composition → studies
<
max> = (ln E <ln A>)+
elongation rate:
shower
maximum:
Observation of longitudinal profile Observation of longitudinal profile
Only events with Xmax in FOV independently of primary type are accepted (no bias)
Auger
Syst uncertainty <
Syst uncertainty < 15 g/cm2 15 g/cm2 Xmax resolution ~
Xmax resolution ~ 20 g/cm2 20 g/cm2 XmaxXmax
4105 hybrid events 4105 hybrid events Xmax resolution Xmax resolution ~ 20 g/cm~20 g/cm22 Systematic uncertainty < 15 g/cm Systematic uncertainty < 15 g/cm22
Mass Composition from X
Mass Composition from X max max measurements
measurements
Angular resolution Angular resolution
Hybrid angular resolution from simulation E~ 1018 eV AR ~ 0.8º (θ<60°)
E>1019 eV AR ~ 0.5º (θ<60°)
SD SD
SD angular resolution from data
3fold E<4 1018 eV AR < 2.2º (θ<60°)
4/5fold 3 1018 <E<1019 eV AR < 1.5º (θ<60°) More fold E>1019 eV AR < 1º (θ<60°)
Hybrid
Hybrid
The sky observed by Auger The sky observed by Auger
Galactic center observed from Auger south Galactic center observed from Auger south
Search for anisotropies in the region of GC 1 EeV < E < 3 EeV
South Argentina North – Colorado (proposal)
CG (Sagittarius A*) (α , δ ) = (266.3°,
29.0°) AGASA search radius
(20°)
obs/exp = 2116/2159.5 SUGAR search
radius (5°) obs/exp = 286/289.7
Galactic Plane Galactic Center (1.5°)
obs/exp = 53.8/45.8
No excess found (1 EeV < E < 3 Eev) No excess found (1 EeV < E < 3 Eev)
The Pierre Auger Coll., Astroparticle Phys. 27 (2007) 244
Search for an excess from
Search for an excess from
GC GC
µ
PeakVEM
SD FD
light diffusing Tyvek walls light flux measured
by absolutely calibrated PMT
Drum: uniform camera illumination
SD e FD Calibration
SD e FD Calibration
One cloud monitor per eye 355 nm steerable lasers
Fd test beam
CLF
Balloons launches
One Lidar station per eye
Atmospheric Monitoring
Atmospheric Monitoring
Surface detector
an array of 1680 Cherenkov stations on a 1.5 km
hexagonal grid
Fluorescence detector
4 buildings overlooking the array each with 6 30°×30°
FOV
The hybrid detector: layout The hybrid detector: layout
~ 60 km 1660 deployed stations
1638 with water 1605 in daq
All FD telescopes operative
A station of the Surface Detector A station of the Surface Detector
• Plastic Tank
• Ultrareflective tyvek liner
• 12 m
3purified water
• 3 PMTs (9 inches)
• Independent power supply (solar panels) s
• GPS antenna
• Communication antenna
DAQ : 40 MHz FADC sampling (10 bit resolution) D
The fluorescence detector
The fluorescence detector
(FD) (FD)
F. Schuessler 44th Rencontres de Moriond, Feb 2009
Conclusions Conclusions
The Pierre Auger Observatory (south site) takes data smoothly First results are extremely encouraging
Energy spectrum (hints on imminent updated results for hspectrum)
Composition
Arrival directions
Search for neutrino
Search for photons (new limits to photon fraction in EeV range) New results with higher statistics are imminent (ICRC09)
Enhancements (HEAT, AMIGA) will allow covering lower energies
The northern site of the Observatory will provide full sky coverage and large statistics at the highest energies
Data in the next few years and comparison with results of other incoming
projects will help clarifying open issues
Results from the Pierre Auger Results from the Pierre Auger
Observatory Observatory
Universit
Universit à à del Salento e INFN Lecce del Salento e INFN Lecce
Lorenzo Perrone for the Pierre Auger Collaboration
Lorenzo Perrone for the Pierre Auger Collaboration
E>10
19.5eV, very low flux
1 particle/(km2 sr century)
Auger
The Pierre Auger Observatory:
The Pierre Auger Observatory:
range of operation range of operation
Need for large detectors
(Auger 3000 km
2)
Particle Data Group
High-Energy cosmic
rays (10
17-10
21) eV
100
Greisen Zatsepin Kuz'min effect:
interaction with the cosmic microwave background (CMB)
nearby sources or new physics?
GZK “horizon”
for protons at 10
20eV
→ ~100 Mpc
similar horizon for Fe
End to the cosmic ray spectrum?
End to the cosmic ray spectrum?
Flux Suppression (GZK cutoff) Flux Suppression (GZK cutoff)
Protons at E >10
Protons at E >102020 eV within 100 Mpc eV within 100 Mpc
Propagation of CR: implications Propagation of CR: implications
E
thr~ 5x10
19eV
− +
+ +
→
+ p e e
p γ
CMBπ
0γ → ∆ → +
+
+p
p
CMBNorthern hemisphere
Northern hemisphere Colorado,USA Colorado,USA
The Pierre Auger Observatory The Pierre Auger Observatory
Southern hemisphere (3000 Southern hemisphere (3000
kmkm22))
Malargüe (Mendoza)Malargüe (Mendoza) Argentina
Argentina Lamar
large and flat region
low density of population (low background due to artificial light)
clean and dry atmospheric
conditions (small cloud coverage)
~~ 50 km
17 Countries 63 Institutions
~ 350 members
(Proposal) (Proposal)
Laser Data
Laser position – Hybrid and FD only (m)
FD vs Hybrid reconstruction
FD vs Hybrid reconstruction
N
γ( ) λ
R
iA T( ) λ
E
depPhotons at diaphragm
E
depN
γ( ) λ
Photons inFD FOV ADC counts
Fluorescence yield (from laboratory measurements)
Detector calibration Geometry
A R
i2Atmosphere
T( ) λ
FD: energy determination FD: energy determination
Longitudinal Profile
Longitudinal Profile Energy “Calorimetric measurement”
dXdX Eem =
∫
dEXmaxXmax
Energy estimator:
particle density at 1000 m from core S(1000)
Systematic uncertainties on energy determination
30% from hadronic interaction models at high energy Direction:
fit to arrival times sequence of particles in shower front
SD reconstruction
SD reconstruction
Energy scale: systematic Energy scale: systematic
uncertainty uncertainty
Nagano + Airfly Nagano + Airfly
FD Calibration FD Calibration Optical Spot, Optical Spot,
Cher. lat. distrib Cher. lat. distrib
107
AGN radiolobes:
(Rachen&Biermann,1993) AGN Jets:
(Norman et al.,1995)
Cygnus A
(z=0.056, d 210 Mpc ≈
5 GHz image, ø 20 kpc) ≈
3C 219 (FR II)
Cosmic Rays: astrophysical sources
Cosmic Rays: astrophysical sources
Upper limit on photon Upper limit on photon
fraction fraction
E>10 19 eV:
SD: Astrop. Phys. 29 (2008), 243 Based on SD signal rise time and shower curvature
FD: Astrop. Phys 27 (2007), 155 Based on Xmax
SD
SD
SD
for reference to models & exp. data see
→ M. Risse, P. Homola, Mod. Phys. Lett. A 22 (2007) 749
topdown models
severely constrained!
favor astrophysical origin of UHECR
reduce systematics in measurements of energy spectrum, pair cross section, mass composition
E (EeV) Ful (95% c.l.) (
2 3.8
3 2.4
5 3.5
10 11.7
systematics:
Xmax, Energy cloud rejection relative efficiency simulations
First limits
First limits on photon fraction in EeV on photon fraction in EeV range
range
V. Scherini 44th Rencontres de Moriond, Feb 2009 arxiv.org/pdf/0903.1127v1
Upper limit on differential neutrino flux
Upper limit on differential neutrino flux
Phys. Rev. Lett.,100 (2008)
↓
Enhancements and future plans Enhancements and future plans
The Pierre Auger Observatory as an ideal site to test alternative measurement techniques
Extension towards the lower energies
• improve detector performance at the transition to extragalactic component between ~10
17and 10
18eV (HEAT and AMIGA)
• cross calibration with other experiments
• Radio detection (AERA)
• Microwave detection (several projects)
FD Auger enhancements FD Auger enhancements
HEAT
3 telescopes nearby Coihueco
30° up to 60° elevation
Std FD HEAT
Simulation E~3 1017 eV
SD Auger enhancements SD Auger enhancements
AMIGA
infill array
muon detectors (scintillators)
5.9 km
2(24 detectors)
Infill Array 433m 23 km
2(42 detectors)
Infill Array 750m
Anisotropy at the highest energy Anisotropy at the highest energy
events with E>57 EeV, angular radius ψ = 3.1°,
× 472 AGN within Dmax=75Mpc (318 in the Auger FOV)
Data Set
01/01/2004 – 31/08/2007
27 high energy events
Centaurus A Centaurus A
obs/exp = 20/5.6
Science, vol 318, issue 5852, 09/11/07
Isotropic chance probability <
1%
20/27 events correlate 20/27 events correlate with nearby AGN
with nearby AGN E>57 EeV
Angular radius of 3.1°
Dmax=75 Mpc
Taking as reference the catalog by VéronCetty and Véron (2006)
Phys. Rev. Lett.,100 (2008)
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