26th Rencontres de Blois: Particle Physics and Cosmology
PRESENT AND FUTURE DIRECTIONS
IN THE OBSERVATION OF ULTRA-HIGH
ENERGY COSMIC RAYS WITH THE
PIERRE AUGER OBSERVATORY
Antonio Bueno on behalf of the Pierre Auger Collaboration
(University of Granada)
1
MOST ENERGETIC PARTICLES
EVER OBSERVED
!
!
!
!
Acceleration mechanisms
Production sources
!
!
Mass composition
Ultra-High Energy
Cosmic Rays:
Unanswered
questions
2
!
!
Fundamental interactions
DETECTOR REQUISITES FOR AIR
SHOWER MEASUREMENTS ABOVE 1 EeV
•
2
Particle flux is extremely small (1 particle per km per century for
20
energies around 10 eV)
•
•
Large areas required!
Hybrid detector required for excellent measurement capabilities •
Combination of ground array (particle detectors, 100%
duty cycle) & optical devices (atmospheric fluorescence,
13% duty cycle)
•
Data-driven calibration of the ground array
3
PIERRE AUGER OBSERVATORY
4 sites, 24+3 telescopes
Malargüe 350 S latitude
≈ 1400 m height ≈ 875 g/cm2
3000 km2
Infill/AMIGA
1660 water Cherenkov detectors
In operation since 2004,
completed in 2008
Triangular grid, side = 1.5 km
4
18 countries
94 institutions
> 500 collaborators
HYBRID DETECTION
E= 72 EeV, θ=54o
81568 events
Loma Amarilla
11940 events
Coihueco
11172 events
25676 events
Los Leones
χ 2/Ndf = 2.7 / 4
CO
LA
LM
dE/dX [PeV/(g/cm2)]
Los Morados
140
Fluorescence detector
profiles
120
100
80
Surface detector
energy estimator
60
40
LL
20
SD
Ecal
0
60
65
70
75
80
85
90
E [EeV]
500
dE
= ∫ dX
dX
1000
5 slant depth [g/cm2]
SCIENTIFIC ACHIEVEMENTS
40 publications, 3260 citations, 81 citations/article
UHECR Flux
Suppression
Spectrum
& CR
Phenomenology
Hints of
anisotropy for
E>55 EeV
Strongest
bounds on
large scale
anisotropies
Arrival Directions
Restrictive
limits 𝛾 on
and ν fluxes
Heavier
composition
above the
ankle
Composition
Interdisciplinary
Science
Solar &
Atmospheric
Physics
6
p-air cross
section
measurement at
√s = 57 TeV
Fundamental Interactions
Muon deficit in
models of
hadronic
interactions
ALL-PARTICLE SPECTRUM
E [eV]
1018
1019
1020
10358
6317
3656
2201
1295
3242
2627
2015
1410
52202
29684
21413
13014
8624
5807
3984
2700
1701
1116
676
427
188
90
E1/2
3
Ea
N19 - SD inclined
101
100
1
1037
S35 , S38 , N19
𝛾2
102
7
𝛾1
S35 / 15 VEM - SD 750 m
S38 / 5 VEM - SD 1500 m
45
1038
103
10
1
10
2
h
E3 J ( E) eV2 km
2 sr 1 yr 1
i
Auger 2013 preliminary
Data-driven calibration
1036
17.5
18.0
18.5
19.0
log10 ( E/eV)
19.5
~130 000 events
7
20.0
20.5
1018
1019
EFD [eV]
1020
Flux suppression established!
MASS COMPOSITION
Auger 2013 preliminary
σ(Xmax) [g/cm2]
〈Xmax〉 [g/cm2]
Xmax
on
prot
850
800
750
600
18
10
19
10
Auger 2013 preliminary
70
proton
60
50
30
EPOS-LHC
QGSJetII-04
Sibyll2.1
650
80
40
iron
700
Fit with empirical Gaisser-Hillas formula
20
0
20
10
E [eV]
iron
10
8
18
10
19
10
20
10
E [eV]
INTERPRETATION IN TERMS OF
<LN A>
A
uger HighLights
33 RD I NTERNATIONAL C OSMIC R AY C ONFERENCE , R IO DE JANEIRO 2013
Auger 2013 preliminary
4
3.5
EPOS-LHC
Auger 2013 preliminary
4
⇥lnA
3.5
SIBYLL 2.1
⇥lnA
⇥lnA
4
3.5
3
3
3
2.5
2.5
2.5
2
2
2
1.5
1.5
1.5
1
1
1
0.5
0.5
0.5
0
17.8 18 18.2 18.4 18.6 18.8 19 19.2 19.4 19.6 19.8
0
17.8 18 18.2 18.4 18.6 18.8 19 19.2 19.4 19.6 19.8
log (E/eV)
3
SIBYLL 2.1
Auger 2013 preliminary
4
3
EPOS-LHC
Auger 2013 preliminary
Proton
0
19.6 19.8
19.8
17.8 18 18.2 18.4 18.6 18.8 19 19.2 19.4 19.6
log (E/eV)
10
2
lnA
4
Auger 2013 preliminary
10
10
2
lnA
2
lnA
log (E/eV)
Iron
QGSJet II-04
4
3
QGSJet II-04
Auger 2013 preliminary
2
2
2
1
1
1
0
0
0
-1
-1
-1
-2
17.8 18 18.2 18.4 18.6 18.8 19 19.2 19.4 19.6 19.8
-2
17.8 18 18.2 18.4 18.6 18.8 19 19.2 19.4 19.6 19.8
-2
17.8 18 18.2 18.4 18.6 18.8 19 19.2 19.419.6
19.6 19.8
19.8
log (E/eV)
10
9
log (E/eV)
10
Pure
beam
log (E/eV)
(E/eV)
10
HADRONIC INTERACTIONS
Inclined showers (i.e. 𝜃>62o)
Signal dominated by muons
Muon counting from FADC for events
with 𝜃∈[0o, 60o] at E= 1019 eV
2.4
Rµ/(E/1019 eV)
2.2
2
E - 14%
2.0
1.8
1.6
Fe EPO
E + 14%
S LHC
Fe QG
SJetII-
1.4
p EPOS
LHC
p QGSJ
etII-04
1.2
1.8
1.0
1.6
Rµ
1.4
04
18.5
19
19.5
log (E/eV)
10
1.2
1
0.8
Systematic Uncert.
QII-04 p
QII-04 Mixed
EPOS-LHC p
EPOS-LHC Mixed
0.6
0.4
0.7
0.8
0.9
1
RE
1.1
1.2
Muon discrepancy
between data and models
of hadronic interactions
1.3
Scale factor to properly describe
Auger data at E= 1019 eV
10
ADVANCING THE UNDERSTANDING OF UHECR
GZK cut off
or sources out of steam?
Is
th
f
Study ra er
cti e
at on a p
fundamental
th (~ ro
interactions en e h 1 ton
er igh 0% at the scale of gie es )
t
s
~100 TeV
?
Importance
Search for of enhanced
new physics: composition
Proton LIV, sensitivity
astronomy?
extra dimensions, …
Anisotropy Are there ultra-high energy
studies photons and based on neutrinos? event-by-event
mass estimation
PLANNED DETECTOR UPGRADE TO OPEN A NEW
FLOURISHING ERA OF UHECR MEASUREMENTS
IMPORTANCE OF ENHANCED MUON
DETECTION
•
•
log10 (Nμmax)
Composition mostly based
on optical observation of
Xmax 15% duty cycle
Surface detector offers 100%
duty cycle ➠Better mass
discrimination capabilities by
Improving separation of
electromagnetic and muonic
shower components!
1019 eV
𝜽=38o
log10 (Nμmax)
•
𝜽=38o
5x1019 eV
12
Xmax (g cm-2)
DETECTOR UPGRADE PLANS
•
Take data until 2023
•
It will triple our
present statistics
•
MARTA
LSD
Improved electronics •
•
Layered Water
RPC (under the WCD)
Cherenkov Detector
Enlarged dynamic
range & faster
sampling
Scintillators
ASCII
On top of
the WCD
Enhanced muon
detection
capabilities
few meters away
from WCD
13
TOSCA
~1.5 m
AMIGA-GRANDE
Buried
scintillator
SUMMARY
•
The Pierre Auger Observatory has provided
copious data of unprecedented quality and size.
•
Intensive campaign to improve detector capabilities:
seeking definitive answers to open key questions.
•
Setting ground for a next-generation UHECR
experiment (ten times bigger in size?).
14
BACK-UP
Communica)on*
antenna*
GPS*antenna*
FADC trace
(40 MHz sampling)
Electronics*enclosure*
40*MHz*FADC,*local*triggers,*10*Wat*
BaBery*
Solar*panels*
Plas)c*tank*with*
12*ton*of*water*
3*PMTs*(9”)*for*Cherenkov*
light*detec)on*
4
Fluorescence
Detector
Diaphragm
Spherical mirror
PMT camera
Camera: 440 PMTs
Shutter
UV Filter (300-400 nm)
Each telescope views 30×30o
A shower event
17
Spherical mirrorR = 3.4 m
SD
SYSTEMATIC UNCERTAINTY OF ENERGY SCALE
RED: NEW
!
!
BLACK: OLD
number of correlating events
CORRELATION WITH AGNS
OF VCV CATALOG
35
50 EeV
55 EeV
60 EeV
70 EeV
80 EeV
30
2σ
3σ
25
)
n
o
i
t
rela
20
15
10
o
r
t
o
Is
5
0
1σ
0
20
40
60
an
h
c
1%
2
(
py
80
r
o
c
ce
100
120
number of events
LARGE SCALE ANISOTROPY
Equatorial dipole amplitude
10
0
Auger 750 m (East-West)
Auger 1500 m (East-West)
Auger 1500 m (Rayleigh)
99% CL upper limits (isotropy)
10-1
10-2
180
10-3
0.01
90
0.1
1
Energy [EeV]
0
10
100
Equatorial dipole amplitude
Phase [deg]
10
0
270
180
0.01
Auger 750 m (East-West)
Auger 1500 m (East-West)
Auger 1500 m (Rayleigh)
0.1
1
Energy [EeV]
10
e
nd
ra
-1
AGASA
G
10
10
Gal
E
AD
-2
C
S
KA
-3
10
100
-4
10
Auger
EAS-TOP
C-G Xgal
A
S
ICE-CUBE
14
10
15
10
16
10
17
10
Energy [eV]
18
10
19
10
log E
!
Xmax
19.2 – 19.4
42.9 ± 5.1 g cm-2
19.2 – 19.3
40.4 ± 6.3 g cm-2
19.3 – 19.4
46.9 ± 7.0 g cm-2
!
!
!
!
Corresponding Pull:-
!
(42.9 – 28.9)/√(4.52 + 5.12) = 2.1
sigma
!
Drawing 71 events (2010) from 194
events (2013) give RMS < 28.9 g
cm-2 at 3.1%
!
Also there is a trials factor
Auger 2013 preliminary
Additional constraints to hadronic interaction models!
CROSS SECTION MEASUREMENT
Contaminations assumed for systematics: < 25% He < 0.5% γ
Integral Flux E>E0 [km-2 sr -1 y-1]
PHOTONS & NEUTRINOS
SHDM
SHDM’
TD
Z-burst
GZK
upper limits 95% C.L.
1
Y
Y
Photons
A
-1
10
A
Hyb 2011
TA 2011
10-2
Neutrinos
Auger SD
Single flavour (90% CL)
-3
10
1019
1020
Energy[eV]
E2 dN/dE [ GeV cm-2 s-1 sr-1 ]
1018
10-4
-5
10
ν limits
Auger (6 yr)
RICE (4.8 yr)
ANITA-II (28.5 days)
10-6
Cosmogenic ν models
p, Fermi-LAT bound [15]
Fe, FRII & SFR evol. [16]
p & mixed [2]
Astrophysical sources
AGN ν [1]
Waxman-Bahcall [14]
PRELIMINARY
10-7
10-8
10-9
10-10
1017
1018
Eν [eV]
1019
1020
1021

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