Recent results from the LHCf experiment Gaku Mitsuka (Nagoya - - PowerPoint PPT Presentation

SLIDE 1

Recent results from the LHCf experiment

Gaku Mitsuka (Nagoya University)

• n behalf of the LHCf Collaboration

ISMD2012 16-21 September 2012, Jan Kochanowski University, Kielce

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SLIDE 2

Outline

• Introduction and Physics motivation
• Analysis results
• Photon analyses at √s=900GeV and 7TeV
• π0 analysis at √s=7TeV
• Conclusions and Future prospects

Keywords:

• (Ultra high energy) Cosmic rays
• LHC
• Forward particle productions

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O.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, H.Menjo, P .Papini, S.Ricciarini, G.Castellini, A. Viciani INFN, Univ. di Firenze A.Tricomi INFN, Univ. di Catania K.Fukatsu, Y.Itow, K.Kawade, T.Mase, K.Masuda, Y.Matsubara, G.Mitsuka, K.Noda,T.Sako, K.Suzuki, K.Taki Solar-Terrestrial Environment Laboratory, Nagoya University K.Yoshida Shibaura Institute of Technology K.Kasahara, M.Nakai, Y.Shimizu, S.Torii Waseda University T.Tamura Kanagawa University Y.Muraki(Spokes person) Konan University M.Haguenauer Ecole Polytechnique W.C.Turner LBNL, Berkeley J.Velasco, A.Faus IFIC, Centro Mixto CSIC-UVEG A-L.Perrot CERN

Totally ~30 collaborators

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Energy spectra of high energy cosmic rays

Energy (eV)

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sr GeV sec)

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Flux (m

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• 13

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• 4

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• 1

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4

10

• sec)

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(1 particle/m Knee

• year)

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(1 particle/m Ankle

• year)

2

(1 particle/km

• century)

2

(1 particle/km

LEAP - satellite Proton - satellite Yakustk - ground array Haverah Park - ground array Akeno - ground array AGASA - ground array Fly's Eye - air fluorescence HiRes1 mono - air fluorescence HiRes2 mono - air fluorescence HiRes Stereo - air fluorescence Auger - hybrid

0.9TeV 7TeV 14TeV

Direct Indirect

Energy [eV/particle]

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]

1.4

eV

−1

sr

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yr

−2

J(E) [km

2.4

Scaled flux E

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Tibet&QGSJET KASCADE&QGSJET 0.80 × AGASA, E HiRes I/II 1.15 × Auger SD&FD, E

4.5 PeV) × =Z

c

galactic (E proton helium CNO 24 ≤ Z ≤ 10 25 ≥ Z

Extragalactic source Standard (i.e. widely believed) model

Energy, Composition, & direction →Source of cosmic ray →Structure of the universe (goal)

(M. Unger ECRS 2008)

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• It is not possible to directly* measure

cosmic rays above 1014eV, but possible indirectly using the cascade shower of daughter particles, i.e. Extensive Air- Shower(EAS).

• Composition and energy of cosmic rays

afgect the generation of EAS.

• Then understanding of high-energy

cosmic ray owes to the indirect technique: comparison between the MC simulation of EAS and observation.

• Largest systematic uncertainty of indirect

measurement is caused by the finite understanding of the hadronic interaction of cosmic ray in atmosphere.

Altitude [km] Radius [km]

* direct measurement of cosmic ray <1014eV is done by balloon, satellite, and ISS.

γ p Fe

Indirect measurement of cosmic rays

Xmax

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Hadronic interactions for CR physics

CERN-LHCC-2006-004, 2008 JINST 3 S08006.

What should be measured by LHCf ??

• 1. Energy spectra of γ, π0 and n

→ Shower shape and µ at ground.

• 2. pT spectra

→ Shower lateral distribution at ground.

• 3. ECMS (in)dependence of the spectra

→ Predictive power in UHE region.

• 4. Nuclear efgects

→ Cosmic ray interaction is NOT p-p.

Many models exist for CR physics

• QGSJET (S. Ostapchenko)
• EPOS (K. Werner and T. Pierog)
• etc...

which address on (semi-hard) soft-QCD.

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Arm2

140m

• p-p collision at √s=14TeV corresponds to

Elab=1017eV (~ extra-galactic source).

• Detectors are located at the best position to

measure the large energy flow that strongly contributes the air-shower development.

• √s=900GeV and 7TeV in 2009-2010

pA collisions in 2013. Arm1

The LHCf detectors

Arm2

Silicon strip detector 1ch~160µm η

• 15
• 10
• 5

5 10 15

[TeV] η dE/d

0.5 1 1.5 2 ATLAS/CMS CASTOR LHCf/ZDC RPs

p-p@14TeV

10(W)cm x 10cm(H) x 30cm(D) Sampling calorimeter, 44X0, 1.6λ

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Photon event analyses

π0, η, etc. Large tower Small tower γ IP π0, η, etc. Large tower Small tower γ IP (η>~10) (8.8<η<9.5)

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Photon analysis at √s=900GeV

Combined data (Arm1 and Arm2) vs MC simulations

• None of interaction models perfectly reproduce the LHCf data.
• EPOS and SIBYLL(x~2) show a reasonable agreement with the LHCf data.
• DPMJET, QGSJET and PYTHIA are in good agreement Eγ<200GeV, but

harder above 200GeV → ECMS dependent or independent ?

PLB 715 (2012) 293-303.

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Photon analysis at √s=7TeV

/GeV

ine

Events/N

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Ldt=0.68+0.53nb

∫

Data 2010, Data 2010, Stat. + Syst. error DPMJET 3.04 QGSJET II-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145

=7TeV s LHCf Gamma-ray like

°

= 360 φ Δ > 10.94, η

/GeV

ine

Events/N

• 10

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• 8

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Ldt=0.68+0.53nb

∫

Data 2010, Data 2010, Stat. + Syst. error DPMJET 3.04 QGSJET II-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145

=7TeV s LHCf Gamma-ray like

°

= 20 φ Δ < 8.99, η 8.81 <

Energy[GeV] 500 1000 1500 2000 2500 3000 3500 MC/Data 0.5 1 1.5 2 2.5 Energy[GeV] 500 1000 1500 2000 2500 3000 3500 MC/Data 0.5 1 1.5 2 2.5

Combined data (Arm1 and Arm2) vs MC simulations

PLB 703 (2011) 128–134.

• Again, none of interaction models perfectly reproduce the LHCf data.
• EPOS has the smallest η-dependence relative to the LHCf data.
• QGSJET and SIBYLL show the somewhat large dependent on η.
• Tendencies at 900GeV are mostly same as 7TeV except for QGSJET and SIBYLL.

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π0 event analysis

π0 Large tower Small tower γ IP γ (8.9<y<11.0)

[MeV]

γ γ

Reconstructed m 80 100 120 140 160 180 Events / (1 MeV) 100 200 300 400 500

• 1

Ldt=2.53nb

∫

=7TeV, s LHCf-Arm1 9.0 < y < 9.2

[GeV]

T

P 0.1 0.2 0.3 0.4 0.5 0.6 Events / (0.02) 1 10

2

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3

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True spectra Measured spectra Unfolded spectra(by UE-EPOS) Unfolded spectra(by UE-PYTHIA)

=7TeV s LHCf-Arm1 9.0 < y < 11.0 LHCf-Arm1 √s=7TeV 9.0<y<11.0

True EPOS Unfolded(by π0+EPOS) Unfolded(by π0+PYTHIA) Measured EPOS

Rapidity 9 9.5 10 10.5 11 [GeV/c]

T

p 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

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E=1TeV E=2TeV E=3TeV

LHCf-Arm1

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• LHCf data are mostly bracketed among hadronic interaction models.
• DPMJET, SIBYLL(x2) and PYTHIA are apparently harder, while QGSJET2 is softer.

π0 analysis at √s=7TeV

MC simulations vs Combined spectra (Arm1 and Arm2 data)

Submitted to PRD (arXiv:1205.4578).

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

]

• 2

[GeV

3

/dp σ

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Ed

inel

σ 1/

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10 1

Data 2010 DPMJET 3.04 QGSJET II-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145

• 1

Ldt=2.53+1.90nb

∫

π =7TeV s LHCf 8.9 < y < 9.0

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

]

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[GeV

3

/dp σ

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Ed

inel

σ 1/

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Ldt=2.53+1.90nb

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π =7TeV s LHCf 9.0 < y < 9.2

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

]

• 2

[GeV

3

/dp σ

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Ed

inel

σ 1/

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Ldt=2.53+1.90nb

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π =7TeV s LHCf 9.2 < y < 9.4

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

]

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[GeV

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/dp σ

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inel

σ 1/

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π =7TeV s LHCf 9.4 < y < 9.6

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

]

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[GeV

3

/dp σ

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Ed

inel

σ 1/

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Ldt=2.53+1.90nb

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π =7TeV s LHCf 9.6 < y < 10.0

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

]

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[GeV

3

/dp σ

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Ed

inel

σ 1/

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π =7TeV s LHCf 10.0 < y < 11.0

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π0 analysis at √s=7TeV

MC simulations / Combined spectra (Arm1 and Arm2 data)

• EPOS agrees well with the data among all models here.
• QGSJET allows only one quark exchange in collision → leading is always baryon.

Submitted to PRD (arXiv:1205.4578).

DPMJET 3.04 QGSJET II-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145

π =7TeV s LHCf 8.9 < y < 9.0

• 1

Ldt=2.53+1.90nb

∫

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

MC/Data

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

π =7TeV s LHCf 9.0 < y < 9.2

• 1

Ldt=2.53+1.90nb

∫

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

MC/Data

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

π =7TeV s LHCf 9.2 < y < 9.4

• 1

Ldt=2.53+1.90nb

∫

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

MC/Data

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

π =7TeV s LHCf 9.4 < y < 9.6

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Ldt=2.53+1.90nb

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[GeV]

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p

0.1 0.2 0.3 0.4 0.5 0.6

MC/Data

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

π =7TeV s LHCf 9.6 < y < 10.0

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Ldt=2.53+1.90nb

∫

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

MC/Data

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

π =7TeV s LHCf 10.0 < y < 11.0

• 1

Ldt=2.53+1.90nb

∫

[GeV]

T

p

0.1 0.2 0.3 0.4 0.5 0.6

MC/Data

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

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LHCf (this analysis) UA7

S) p QGSJET II-03 (Sp QGSJET II-03 (LHC) S) p SIBYLL 2.1 (Sp SIBYLL 2.1 (LHC) S) p EPOS 1.99 (Sp EPOS 1.99 (LHC)

y Δ

• 2
• 1.5
• 1
• 0.5

0.5 1 1.5 > [MeV]

T

<p 50 100 150 200 250 300 350 400

Data 2010 Exponential Gaussian

[GeV/c]

T

p 0.1 0.2 0.3 0.4 0.5 0.6

3

/dp σ

3

Ed

inel

σ 1/

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π =7TeV s LHCf 9.4 < y < 9.6

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Ldt=2.53+1.91nb

∫

π0 analysis at √s=7TeV

• Systematic uncertainty of LHCf data is <10%.
• Compared with the UA7 data (√s=630GeV)

and MC simulations (QGSJET, SIBYLL, EPOS).

• Smallest dependence on ECMS is found in

EPOS and it is consistent with LHCf and UA7.

• Large ECMS dependence is found in SIBYLL

→ this indicates the prediction at UHE region may difger from at the LHC energy region.

PLB 242 531 (1990)

Δy = ybeam - y Submitted to PRD (arXiv:1205.4578).

Average pT vs Δy

• 1. Thermodynamics (Hagedron model)

hpTi = r πmπ0T 2 K2(mπ0/T) K3/2(mπ0/T)

1 σinel E d3σ dp3 = A · exp(− q pT2 + m2

π0/T)

• 2. Gauss distribution

1 σinel E d3σ dp3 = A · exp(−p2

T/σ2 Gauss)

πσ2

Gauss

hpTi = pπ 2 σGauss

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Conclusions and Future prospects

• LHCf has measured the energy and transverse

momentum spectrum of the forward emitted particles at the 900GeV and 7TeV proton-proton collisions.

• Consistent π0 spectra are obtained between the

Arm1 and Arm2 detector. Combined spectra agree with the prediction by EPOS for the pT spectra and <pT>.

• Many analyses are ongoing:
• Neutron analysis → energy flow of EAS and µ at

ground

• Extends to other meson/baryon (e.g. η, K0, Λ)

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Backup

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E [eV]

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10

19

10

]

2

[g/cm 〉

max

X 〈

650 700 750 800 850

proton iron

QGSJETII Sibyll2.1 EPOSv1.99

Energy spectra of high energy cosmic rays

Energy (eV)

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sr GeV sec)

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Flux (m

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• 1

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10

• sec)

2

(1 particle/m Knee

• year)

2

(1 particle/m Ankle

• year)

2

(1 particle/km

• century)

2

(1 particle/km

LEAP - satellite Proton - satellite Yakustk - ground array Haverah Park - ground array Akeno - ground array AGASA - ground array Fly's Eye - air fluorescence HiRes1 mono - air fluorescence HiRes2 mono - air fluorescence HiRes Stereo - air fluorescence Auger - hybrid

0.9TeV 7TeV 14TeV

Direct Indirect

(E/eV)

10

log

18 18.5 19 19.5 20 20.5

))

• 1

sr

• 1

s

• 2

( E J /(m

10

log

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E[eV]

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10 × 2

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10 × 2

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10 × 2

Auger (ICRC 2011) Telescope Array AGASA Yakutsk HiRes I HiRes II

Flattening “Ankle” Steepening (Cutoff)

GZK cutofg ?

Energy, Composition, & direction →Source of cosmic ray →Structure of the universe (goal)

Model uncertainty Auger UHECR2012

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Hadronic interactions for CR physics

CERN-LHCC-2006-004, 2008 JINST 3 S08006.

0.01 0.1 1 0.01 0.1 1

dσ dX XF

ad-hoc A ad-hoc B

dσ 1

F inela

XF

1e+06 1e+07 1e+08 200 300 400 500 600 700 800 900 1000

Number of Electrons

Vertical Depth (g/cm ) Vertical shower

ad-hoc A ad-hoc B

2

Model uncertainty on Xmax

Xmax(A) Xmax(B)

What should be measured by LHCf ??

• 1. Energy spectra of γ, π0 and n

→ Shower shape and µ at ground.

• 2. pT spectra

→ Shower lateral distribution at ground.

• 3. ECMS (in)dependence of the spectra

→ Predictive power in UHE region.

• 4. Nuclear efgects

→ Cosmic ray interaction is NOT p-p.

Many models exist for CR physics

• QGSJET (S. Ostapchenko)
• EPOS (K. Werner and T. Pierog)
• etc...

which address on (semi-hard) soft-QCD.

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Photon analysis at √s=900GeV

Arm1 Arm2

Beam pipe shadow

Submitted to PLB.

Cross section of the LHCf detectors

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]

2

Xmax [g/cm 400 500 600 700 800 900 1000 Events(/20) 20 40 60 80 100 120 140

Proton-Air simulations eV

16

10 × = 2.5

proton

E

DPMJET 3 DPMJET 3(Modified)

Energy [GeV] 500 1000 1500 2000 2500 3000 3500 /GeV

ine

Events/N

• 10

10

• 9

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• 8

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• 1

Ldt=0.5nb

∫

Data 2010, DPMJET 3 DPMJET 3(Modified)

=7TeV s LHCf Gamma-ray like

°

= 360 φ Δ > 10.94, η

Impact on Air-shower production

Constraint of the LHCf results to CR observations is estimated by proton-air simulations:

• DPMJET3 outputs are artificially modified to be parallel to the LHCf spectra

(split a high-energy π0 to two low-energy π0s)

• Modification factor is applied to simulations of the proton-air collision.
• EProton is 2.5x1016eV, equivalent to the energy in lab frame of p-p collision

at √s=7TeV Results in decrease of ~30 g/cm2. p-p at √s=7TeV(Elab=2.5x1016eV) p-Air at Elab=2.5x1016eV

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Fit ansatz to pT spectra

Data 2010 Exponential Gaussian

[GeV]

T

p 0.1 0.2 0.3 0.4 0.5 0.6 ]

• 2

[GeV

3

/dp σ

3

Ed

inel

σ 1/

• 4

10

• 3

10

• 2

10

• 1

10 1

π =7TeV s LHCf 9.2 < y < 9.4

• 1

Ldt=2.53+1.91nb

∫

[GeV]

T

p 0.1 0.2 0.3 0.4 0.5 0.6 ]

• 2

[GeV

3

/dp σ

3

Ed

inel

σ 1/

• 4

10

• 3

10

• 2

10

• 1

10 1

π =7TeV s LHCf 9.4 < y < 9.6

• 1

Ldt=2.53+1.91nb

∫

[GeV]

T

p 0.1 0.2 0.3 0.4 0.5 0.6 Fit/Data 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Stat.+syst. uncertainty Exponential Gaussian

π =7TeV s LHCf 9.2 < y < 9.4

• 1

Ldt=2.53+1.91nb

∫

[GeV]

T

p 0.1 0.2 0.3 0.4 0.5 0.6 Fit/Data 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

π =7TeV s LHCf 9.4 < y < 9.6

• 1

Ldt=2.53+1.91nb

∫

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Fit ansatz to pT spectra

Exponential fit Gaussian fit Numerical integration Rapidity χ2 (dof) T hpTi

• Stat. error χ2 (dof) σGauss

hpTi

• Stat. error pupper

T

hpTi

• Stat. error

[MeV] [MeV] [MeV] [MeV] [MeV] [MeV] [GeV] [MeV] [MeV] [8.9, 9.0] 0.6 (7) 83.8 201.4 13.5 2.0 (7) 259.0 229.6 13.1 [9.0, 9.2] 8.2 (7) 75.2 184.1 5.0 0.9 (7) 234.7 208.0 4.6 [9.2, 9.4] 28.7 (8) 61.7 164.0 2.8 6.9 (8) 201.8 178.9 3.4 0.6 167.7 9.6 [9.4, 9.6] 66.3 (6) 52.8 140.3 1.9 3.3 (6) 166.3 147.4 2.7 0.4 144.8 3.2 [9.6, 10.0] 14.0 (5) 43.3 123.5 2.2 0.3 (5) 139.2 123.3 3.0 0.4 117.0 2.1 [10.0, 11.0] 9.0 (2) 21.3 77.7 2.3 2.1 (2) 84.8 75.1 2.9 0.2 76.9 2.6

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Scaling of the photon spectra

Arm1-Data Preliminary

• Good agreement of each XF scaling spectrum indicates a weak

dependence of <pT> on ECMS.

• Does this indicate the weak pT dependence of π0 ?

Data 2010 at √s=7TeV (η>10.94) Data 2010 at √s=900GeV Small tower : 22.6% Large tower : 77.4% Scaling factor : 0.1

Arm1-EPOS Preliminary

1 σinel dσγ dXF

• η<limited /

1 σinel dσγ pTdpTdXF hpTidpT

23