Ultra high energy cosmic
ray and LHCf data
Nobuyuki Sakurai

2013/11/14

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Outline• Ultra high energy cosmic ray (UHECR)• Observation of UHECRs• Hadronic interaction and UHECR observation• Collider experiment dedicated UHECR study~ LHCf ~• Summary

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Ultra high energy cosmicray (UHECR)

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Ultra High Energy Cosmic Ray

Flux (m2 sr s GeV)-1102

Ultra high energy cosmic rayKnee

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E J
Beam energy per
proton of LHC

10-28
1082013/11/14

Ankle

1 particle
per 1 km2
per 100 years

Energy (eV)1020

4 2010CR source candidates of UHECRs• Top-down model• Decay or annihilation ofsuper heavy particle• Z burst• Topological defectHillas plot

• Bottom up model• Neutron star
• Active galactic nuclei• Gamma ray burst• Galactic cluster• Radio galaxy
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Greisen, Zatsepin and Kuzmin (GZK) Cutoff

Interaction mechanism between
CMB and UHE proton.
 Mean free path ~ 50 Mpc

Flux suppression above 5x1019 eV
is expected.
 AGASA  beyond HiRes, Auger  suppression

Large systematic error
 AGASA 18%, HiRes 17%, Auger 22%
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6Models of spectrum structure

D. Allard et al. (2007)

 Suppression = GZK cutoff
 “ankle”= “dip” by pair-creationp   CMBR  p  e   e  Transition of the primary
composition before “ankle”
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R. Aloisio et al. (2011)

 Suppression = Accerelationlimit
 “ankle” = Different CR source
 “ankle” is not “dip”
Key is “composition measurement”
7Observation of UHECRs

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Air shower phenomena

Longitudinaldevelopment

Xmax

Lateral distribution

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Made by A. Oshima (Chubu U.)

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Surface detector array (SD)
Detect secondary particles bycounter array on the ground.
Strong point
100% duty
Relatively cheap
Lateral distributions of particle
density and timing.
Weak point
Energy reconstruction depends
upon the hadron interaction
largely.

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10Fluorescence Detector (FD)
Detect air fluorescence light bytelescope.

Strong point
 Longitudinal development of
air shower = Primary
composition
 Energy can be measured
calorimetrically.
Weak point Duty is less than 10%
 Depends on the atmosphericconditions.

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11Telescope Array experiment(TA) Western desert of Utah, USA Detection area ~ 700 km2
 Largest detector in northernhemisphere
Middle Drum (MD)507 Surface detectors (SD)

 Opereation : 2008 Mar.～

Fluorescence detector(FD) Station (BRM&LR)
Long Ridge (LR)Black Rock Mesa (BRM)

35 km
FD

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SD

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Energy spectrum of UHECRs
5.7x10^19eV
5.0x10^18eV

No suppression: 68.1

Observed : 26
Significance= 5.7s2013/11/14

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Energy spectrum of UHECRs
p+ (2.7K)
 p+e++e-

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p+ (2.7K)
 D p+p14

Xmax : Primary composition
For same energy…
Proton ironLongitudinal development

ProtonIron

Primary particle canbe estimated bylong. development
information.

Averaged Xmax
Proton Xmax depends on primaryenergy.
 Xmax difference between proton
and iron is about 100 g/cm2.
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Iron15

Primary composition of UHECRs
TA Stereo

ICRC2013 preliminary

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Correlation with AGN• 472 AGN from 2006 Veron catalog with z<0.018• E>57EeV, zenith angle<45deg, N=42(5yr)• Separation angle < 3.1deg

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17Correlation with AGN• 17 events correlate out of 42  p=0.014

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Summary of TA latest results• Results of 5 years TA operation was presented.
• Energy spectrum• Significance of the suppression is 5.7s above
5.4x10^19eV.

• Composition• Consistent with proton above 1.6x10^18eV.

• Arrival direction• Some hints?

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Hadronic interaction &UHECR observation

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Summary of composition studies
 Around 1018 eV, composition ischanging. (Stereo Fly’s Eye,HiRes/MIA) Above 1018.5 eV,Proton Proton (TA & HiRes) Light nuclei (Auger)

Iron
1019 eV1018 eV

Telescope Array (TA)ProtonProtonProtonIron

1018 eV1019 eV

Iron
1018 eV 1019 eV

Stereo Fly’s Eye
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Iron

HiRes/MIA and HiRes(High Resolution Fly’s Eye)1018 eV1019 eV

Pierre Auger Observatory(Auger)21

Known anomalies of air shower
observables(1)• # of muons on the ground is too much.

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Known anomalies of air shower
observables(2)• E.M component of secondary particle on theground is also too mach.
AugerTAE(FD) = 1.27xE(SD)

E(FD) = E(SD)2013/11/14

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Collider experimentdedicated UHECR study(LHCf)

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Air Shower study using collder① Inelastic cross section
If large s: rapid development
If small s: deep penetrating④ secondaryinteractions
nucleon, p② Forward energy spectrum
If softer shallow development
If harder deep penetrating

If large k (p0s carry more energy)
rapid development
If small k (baryons carry more energy)
deep penetrating
Forward Physics with the LHCf experiment25

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Where to be measured at collidersMultiplicity

Energy flux

All particles

neutralMost of the particles produced into central,
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Most of the energy flows into forward

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The LHC forward experiment
LHCf Arm#1

ATLAS
140m

Two independent detectors ateither side of IP1 (Arm#1, Arm#2 )Beam pipe
Charged particles (+)

Beam
96mm

Neutralparticles

LHCf Arm#2

Charged particles (-)• All charged particles are swept by dipole magnet• Neutral particles (photons and neutrons) arrive at LHCf
2013/11/14• 0 degree is covered27

LHCf Detectors
 Imaging sampling shower calorimeters Two calorimeter towers in each of Arm1 and Arm2
 Each tower has 44 r.l. of Tungsten,16 sampling scintillator and 4
position sensitive layers
Arm#1 Detector
20mmx20mm+40mmx40mm
4 XY SciFi+MAPMT

Arm#2 Detector
25mmx25mm+32mmx32mm
4 XY
Silicon strip detectors
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Data 201010-2-1

10-2

LHCf s=7TeV p0
9.2 < y < 9.41

ò Ldt=2.53+1.90nb

3

ò Ldt=2.53+1.90nb

10-1

1/ sinel Ed3s/dp [GeV-2c3]-1

LHCf s=7TeV p0
9.0 < y < 9.213

ò Ldt=2.53+1.90nb

10-1

1/ sinel Ed3s/dp [GeV-2c3]

LHCf s=7TeV p0
8.9 < y < 9.0131/ sinel Ed3s/dp [GeV-2c3]

1110-1-110-2

DPMJET 3.04
QGSJET II-03-3-3

SIBYLL 2.1

10-3

1010

EPOS 1.99
PYTHIA 8.145
0.2

0.3

0.4

0.5

10-40

0.6

0.1

0.2

0.3

0.4

p [GeV/c]

10-1

10-2-3

ò Ldt=2.53+1.90nb

10-1-1

10-2-31010-4LHCf s=7TeV p09.6 < y < 10.013-1

0.1

0.2

0.3

0.4

0.5

0.6

0.2

0.30.410-400.50.6

p [GeV/c]
TLHCf s=7TeV p0
10.0 < y < 11.01

ò Ldt=2.53+1.90nb

10-1-1

10-2-31000.1T

1/ sinel Ed3s/dp [GeV-2c3]

ò Ldt=2.53+1.90nb

3

1/ sinel Ed3s/dp [GeV-2c3]

LHCf s=7TeV p0
9.4 < y < 9.6

10-40

0.6

p [GeV/c]

T1

0.5

30.1

1/ sinel Ed3s/dp [GeV-2c3]

10-4 0100.1

0.2

pT [GeV/c]

0.30.40.50.6

pT [GeV/c]

10-400.1

0.20.30.40.50.6

pT [GeV/c]• EPOS1.99 show the best agreement with data in the models.
• DPMJET and PYTHIA have harder spectra than data (“popcorn model”)• QGSJET has softer spectrum than data (only one quark exchange is allowed)

F I G . 7: (color online). Combined pT sp ectra of the A rm 1 and A rm 2 detectors (black dots) and the total uncertainties (shadedtriangles) com pared with the predicted sp ectra by hadronic interaction m odels.

T he values of pT obtained in Table I I and Table I I I
Physicsagreement.
with the LHCfexperiment
are Forward
in reasonable
W hena speciﬁ c value29
ofR apidity

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puT p p erpTTotal uncertainty[G eV /c] [M eV /c][M eV /c]`Large tower
7 TeV pp

Small tower
7 TeV pp

Courtesy of K. Kawade (Nagoya U, STE lab.)
Forward Physics with the LHCf experiment30

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No rapidity selection
No efficiency correction
Only statistical error

Example of model modification(1)DPMJET3+filter
photon spectrum
π0 spectrum~30g/cm2
2.5x1016 eV proton

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Example of model modification(2)• Toy model study of nucleon contribution• High rapidity & high energy pions are changed tonucleon (Blue case).
• All nucleons are changed to pions (Red case).

Long. development# of EM component

Long. development# of muonsMore realistic modification studies are going on now.
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Summary• Latest results of TA shows• Spectrum shape & Xmax study are consistent with
proton primary case.
• There is some hint of source in arrival direction
distribution.

• Hadronic interaction study is very important forinterpretations of UHECR observation.
• Uncertainty of composition study.
• Anomalies of air shower observables.

• Hadrons in very forward region affects the airshower development.
• LHCf data will improve the UHECR observation.
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