Observation of Ultra-High Energy
Cosmic Rays (UHECRs)- status and prospects CosPA 2013, Honolulu
November 15th, 2013
M.Fukushima
ICRR, Univ. of Tokyo

UHECRs Detector• Pierre Auger Observatory (Auger) in Malargue, Argentina• Telescope Array (TA) Experiment in Utah, USA

Ground Array + Air Fluorescence Telescope
SD & FD
Simultaneousmeasurement

FD• Total absorption calorimetry > Energy scale• Imaging > Xmax > Particle Composition• Duty ~ 10%SD• Duty ~100%• High Statistics > Spectral shape• + ~Uniform sky sampling > AnisotropyAugerSD
Surface
Detector

S=10m2, h=1.2m
Water Tank
µ based sampling
S=3m2, t=1.2cm
Plastic Scint. 2-layer
EM based samplingTAFDFluorescence
Detector

1.5o pixel(256 PMTs)

1o pixel

507 Surface Particle Detectors
cover 680 km2

3 Fluores. Telescope stations
overlook the array.

Utah, USA39.3 0 N
112.9 0 W
Alt. 1400 m

Air Fluorescence : Reference model established
Reference Model proposed by B. Keilhauer & experimental groups
at UHECR2012 @CERN.
AirFLY• Spectrum at 1013 hPa and 293 K:AirFLY• Extinction, T and humidity dep. : AirFLY, N.Sakaki et al.
• Normalization (AF Yield at 337nm) : open

B. Keilhauer et al.,UHECR 2012arXiv:1210.1319

M. Ave et al.
AirFLY collaboration T. Shibata,ICRC 2013
ApP 28(2007)41

Air Fluorescence : 337nm Yield [photons/MeV]
Integrated Yield from Electron Beamrelative to AirFLY yield.
■ ELS DATA
AirFLY 4% sys error

AirFLY = 5.61 ± 0.06 (stat) ± 0.22 (sys)for 1013 hPa and 293 K Controlled laboratory
measurement

TA measured the AF yield in situ using• 40 MeV electron beam from linac injected into the air.
• FD telescope with calib. database.
• Reference AF Model (spectrum, P-T-RH dependence)• ∆E by GEANT-4 converted to photons with AirFLY yield.
Measurement in situ
at TA.

weighedaverage=0.99

ELS (data) / AirFLY (MC)= 0.96*) ± 0.01 (stat) ± 0.15 (sys)for ~860 hPa, -170 ~ 170 C*) 0.99 with -3% correction not included in MC M. Ave et al.
T. Shibata,ICRC 2013

AirFLY collaboration
ApP 42(2013)90

Energy Calibration E’SD (S38 for Auger) vs EFD using hybrid eventsTAAuger• Good correlation (~linear) withparticle density at 1000m (Auger) ,800m (TA) from corefor 1018.5 < E <1019.8 eV.
• Limited statistics for 1019.5 eV < E••• S-800 = # of particles at D=800m• S-800(E’SD , th) map is obtained byair shower simulation.

• S38 = # of VEMs at θ=380 and D=1000m• Zenith attenuation of VEMs obtained
from Constant Intensity Cut (CIC)

Auger E-scale updated (ICRC2013)using (nearly) reference model.
TA E-scale unchanged:
 Spectrum: FLASH Yield: Kakimoto et al. extended
 same as HiResV. Verzi,ICRC2013

Energy Spectrum

Energy Spectrum of Cosmic Rays
Primary cosmic rays:
・ proton, nucleus
・ isotropic arrival（~0.1%）~100 Hz/m2~1 / (100 km2 Year)∝ E -3
LHC beam

10 9 eV

ENERGY

10 20 eV

Updated at ICRC2013
with New Energy analysis
Energy Increased by
16% at 1018.0 eV and
10% at 1019 eV(mainly not by new AFY)
Dip and “Cutoff ”
confirmed.

Y. Lettessier-Selvon,
ICRC 2013

Updated at ICRC2013

Dip and “Cutoff ”
confirmed.

(2011)

H. SagawaD.Bergman
ICRC 2013

Spectrum at UHE : Auger and TA

D. Bergman
ICRC 2013

From Y. Tsunesada
ICRC 2013
Rapporteur Talk

Spectrum at UHE : Auger and TAResults of Broken Power Law Fit

guide for eyes

AugerTAγ-1

3.23±0.01

3.28±0.03

EANKLE

1018.72 eV

1018.70 eV

γ-2

2.63±0.02

2.69±0.03

E1/2

1019.63 eV

1019.74 eV• Spectral shape: Auger and TA agree
well for E < ~1019.3 eV if overall
E-scale shifted by 10%.
• E1/2: EAUGER = 0.78 x ETA(w/o 10% rescale)
D. Bergman
ICRC 2013

From Y. Tsunesada
ICRC 2013
Rapporteur TalkAstrophysical Scenario : AUGER• Models calculated with CRPropa andvalidated with SimProp.
• Spectrum alone is not enough toDiscriminate between scenarios.
• Cutoff by Acceleration limit isnot excluded?

A. Schulz,ICRC 2013

Astrophysical Scenario: TAFit with extra-galactic proton
Source Distribution• Uniform• LSS (~2MASS XSCz)
Energy Loss with
• CMB
• Infra-Red
using CRPropa 2.0 simulation
checked with analytic ∆E.
No magnetic field.
Uniform : χ2/ NDF = 16.0 / 17LSS:16.2 / 17

4-parameter fit• Injection spectrum : E -pEmax = 1021 eV• Evolution : (1+z)m• Flux normalization• Energy scale

For LSSP = 2.37 +0.08 –0.08
m = 5.2 +1.2 -1.3
Log E’/E = - 0.02 +0.04 –0.05
E. Kido
ICRC 2013

Particle Composition

Auger Xmax••••

(updated at ICRC 2013)+ statistics
AFY updated.
PSF updated.
Calibration etc.

<Xmax> larger+13 g/cm2 at 1018eV ~+6 g/cm2 at 1019.5eV
RMS(Xmax) larger< 10 g/cm2for 1018-19 eV

Updated models: EPOS-LHC andQGSJET-II-04 are used for MC rails.

E.J. Ahn, M. Unger
ICRC 2013

IF PURE

Auger LnA Study

FeNeCNO<lnA>

LiHe<Xmax>, σ(Xmax)<lnA>, σlnAUsing
DP : elongation rate
σj 2 : mass averaged shower fluctuation

HMIXEDBottom Line of Auger Xmax study:PURE
2σlnA
E.J. Ahn, M. Unger
ICRC 2013

TA XmaxHybrid Xmax (MD station)(updated @ICRC2013)••

Hybrid Xmax added+ statistics andAnalysis updatedfor Stereo Xmax

•Analysis using
QGSJET-II-03
SIBYLLQGSJET-I

NO direct comparison with Auger Xmax

QGSJET-II-03 is used for MC rails.

1018.6 eV

1019.4 eVTA Xmax
QGSJET-II-3

K-S test: proton vs Fe<Xmax> and Xmax distribution
is consistent with proton by stereo and hybrid analyses.

1018.6 eV

1019.4 eVTA Xmax
QGSJET-II-3

Difference between Auger and TA on Xmax:

Auger Xmax

• For 1018.6 < E < 1019.4 eV , where Auger’s <LnA> analysis
with QGSJET-II-04 simulation suggests a transition
from proton to <Helium>, TA’s <Xmax> and Xmax
distribution are consistent with proton using QGSJET-II-03.
• Above 1019.4 eV, TA has no stat. power to separate p/Fe.
• Auger’s last point for E > 1019.5 eV is somewhat singularsuggesting pure Li or CNO depending on models.

UHE Gammas and Neutrinos• No candidates found. Limits are updated.
• Some Top-down models are strongly constrained.
• Cosmogenic neutrinos maybe showing up soon.
• GZK gammas may be seen in next generation array.

TAAuger
G. Rubtsov, P. Pieroni,
ICRC 2013 ICRC 2013

Hadronic and Nuclear Intercation
above LHCAir Shower Simulation

p-Air Cross Section by Auger (1018 < E < 1018.5 eV)exp( -XMAX / Λη )Observed Λη matched by tuning σp-Air in model
Inelastic σp-p obtained by Glauber model.

PRL 109(2012) R. Ulrich, K.H. Kampert
062002ICRC 2011 ICRC 2011

Observed SD Signal vs Air Shower Simulation
AugerTA

S(1000m)••

S(800m)E~1019 eV

MC events
with Xmax_DATA=~ Xmax_MC selected
1.3

SD signal is ~1.3 or more larger
than Air Shower simulation at d=800-1000m,
Water Tank (∼µ) or Scintillator (~EM).

G. Farrar, H. Sagawa,
ICRC 2013 ICRC 2013

Observed µ Signal vs Air Shower Simulation
AugerAuger1.5

Number of muons is 1.3 ~ 1.5
larger than Air Shower
Simulation at ~1019 eV.
• Separating µ and EM signal by wave form and timing.
• E ~ 1019 eV and d ~ 1000m• Energy and µ rate of MC can be fitted• Using Xmac_DATA ~ Xmax_MC events.

B. Kegl,ICRC 2013

G. Farrar,
ICRC 2013

Arrival Directions• Anisotropy• Association with Astronomical Objects• Clusters of events

Correlation with AGN in VCVCatalogue within 75Mpc

Auger data until July 2011•••TA

E > 55 EeV in 2011 E-scale
28/84(tot) correlated
P = 0.006 from isotropy

Cen AAGN
3.1o circle
UHECRevents
ApP-34(2010)314

Un-correlated Event

TACorrelated EventCorrelation with VCVin the northFoV• Data until May 2013
• Same condition as Auger•••

E > 57 EeV in TA’s E-scale
17/42(tot) correlated
P = 0.014 from isotropy

Galactic Coordinate
Auto-Correlation

Probability

Opening Angle[deg]

P. Tinyakov,
ICRC2013

TAArrival Directions

Shades: expectation from2MASS XSCz

E > 10 EeVin TA’s E-scaleθ < 550

E > 57 EeV
52 events

2130 events

Compatibility with LSS expectation (shades)

0.05

E > 40 EeV
132 events

GalacticCoordinate

Smearing angle (deg)Compatibility
with Isotropy:p ~ 0.001
for 60 smearing

TAA Cluster of Events in HotspotLooser cuts:• No 1.2 km boarder cut• θ < 550• E > 57 EeV
2008 May – 2013 May:
A Total of 72 events selected.
Oversampling with r = 200 circle
Background from 72 random
isotropic events estimated by MC
Maximum significance in hot
spot is 5.1 σ by Li-Ma method
Post-trials chance probability isbeing estimated.

GPSGP

Summary• Pierre Auger Observatory• Telescope Array

1018.45

E> 57 EeV
SD/FD calib.

σp-airSD750

Hybrid1018.7

SD1500

Inclined

AUGER AGN correlation• 28/84 correlated• P = 0.006 from randoms• Cluster at Cen A?

1019.6(E1/2)

TA with same selection• 17/42 correlated• P = 0.041

Summary of Auger

PAO break pointLSS correlation (60 smearing)

SD/FD calib.

1018.7• P = 0.1 from LSS• P = 0.001 from isotropy• Cluster of ~200 radius near the SG plane
1019.74

E> 57 EeV

(E1/2)

SD fully efficient

Summary of TA

Auger and TA run for next 10 years withprospects

 Auger extension for efficient mu-tag at each SD and TA extension for x4 acceptance (+500 SDs and +1 FD)
Collaboration started on
 S+N all sky coverage, common anisotropy analysis
 understand differences in composition and E-scaleby exchanging calib, analysis, simulation, tank/scint…
Both are harboring RD projects for Radio detection (MHz, GHz, Radar,…) Testing and calibrating JEM-EUSO prototype
 High performance SD/FD/RD for future super-Ground-Array Earth and atmospheric science

JEM-EUSO on ISS (2017 - )super-Ground-ArrayTALE FDTA FD @MD

TAx4:
Near Future
Operations of TA• Construction expected
in 2014-2015.
• Anisotropy and Hotspot :~5σ confirmation by 2019.

TALE SDTA FD @LR
TA SD
TA FD @BRthe 4th FD (TAx4)

extended SD (TAx4)

Upper limit on 1st harmonic amplitude (Auger),but change of phase seen?

Common Isotropy Analysis
using Auger and TA data

AugerTA• Auger/TA acceptance matching• E > 1019 eV in TA scale• Fitting with spherical harmonics

TA+Auger
Equatorial
Coordinate

O. Deligny,ICRC 2013

Octocopter of Auger flew twice in 2012 and 2013
over TA’s night sky with calibrated UV-LED light source.

ELVES observedby Auger FD

Burst of particle showers observedby TA SD associated with lightning
5 bursts in 5 years• Example of one burst• 2 particle showers within 1ms.
• ~10-4 event from randoms.
core•
••
•

lightning

Core locations ~2km apart.
Common “origin” ~3km above Ground.
(highly curved shower front r~3km)
Lightning found within 1ms (NLDN-db)
Lightning location ~ core location
Tonachini, K.H. Kampert
ICRC 2011

T. Okuda
CosPA 2013End090122-225422
TH~380SD Event

Zenith ~ arcsine (ΔT / ΔX)

ΔTΔX

Event “Side” View

Event Top View
X,Y = counter #number = MeV energy deposit (av U+D)
~ 2.5 MeV for vertical muTA

FD EventTA

9.9%

③

3.6%

①

6.2%

②6.5%
3.0%

Total Systematic
Uncertainty

FD Energy Scale④~14%④ Event reconstruction

Auger updated energy scalein ICRC 2013

① Fluores. yield② Atmosphere
Energy Increased by 16% at 1018.0 eV
and 10% at 1019 eV③ Callibration④ （μ, ν to the ground）

V. Verzi,ICRC2013A. Lettessier-Selvon
ICRC2013

SD1500m - SD inclined - SD/FD Hybrid & SD750m Spectra
Consistent among
Different methods

A Schulz
ICRC 2013

SD - FD monocular - SD/FD Hybrid Spectra
Consistent among
Different methods.
Statistics limited
Below 1019.6 eV.

D. Bergman
ICRC 2013

T. Pierog and D. Heck
ICRC 2013

T. Pierog and D. Heck
ICRC 2013

Air Fluorescence : 337nm Yield by TA electron beam calibration
ELS: Shibata et al.

M. Ave et al.
AirFLY collaboration
ApP 42(2013)90

T. Shibata,
ICRC 2013

Air Fluorescence Yield using ELS beam
■ DATA Error of each point < 0.2%
Weighed average=1.22

TA and HiRes use• FLASH spectrum• Modified Yield of Kakimoto et al.
ELS (data) / TA (MC)= 1.18*) ± 0.01 (stat) ± 0.18 (sys)for ~860 hPa, -170 ~ 190 C*) 1.22 with -3% correction not included in MC

A. Lettessier-Selvon,
ICRC2013

EJ. Ahn, M. Unger
ICRC 2013

Expectation from LSS• Sources:
with 5 < D < 250 Mpc : 2MASS galaxy redshift catalog (XSCz)
Apparent magnitude < 12.5 andextrapolate with luminosity density function
Galactic center is extrapolated from surroundings
with D > 250 Mpc: uniform distribution• Propagation:
proton with E-2.4 at origin-dE with CMB interactions (average energy loss)• Magnetic Field:
Gaussian smearing (60 for shown plots)
No regular GMF deflection is introduced
ApJ-757(2012)26