Calibration of thePierre Auger Observatory with

LHC Forward Detectors

Ralf Ulrich

DESY Seminar 18./19. Januar 2011

Cosmic Rays and Extensive Air Showers

Ralf Ulrich 1

Particle Accelerators: Man-Made versus Cosmic Rays

Large Hadron Collider (LHC)

Acceleration to 7TeV

Interactions at 14TeV

Ultra-High Energy Cosmic Rays

Acceleration to > 100.000.000TeV

Interactions up to ∼ 300TeV

Fundamental physics in

extreme environments at

extreme energies

Ralf Ulrich 2

Overview

Our understanding of hadronic interactions at cosmic ray energiesis incomplete

◮ The interpretation of air shower data is very model dependent

◮ Hadronic interaction features are not well constraint at cosmic rayenergies

◮ Calibrate air shower simulations at LHC energy

◮ Determine properties of hadronic interactions at ultra-high energiesfrom cosmic ray data

AstrophysicsParticle Physics

Extensive Air Showers Cosmic Rays

Ralf Ulrich 3

Overview of Cosmic Ray Data

Characterization of Current Situation

Large amounts of high quality cosmic ray dataAuger, HiRes, AGASA, TA, Future: Auger-North, JEM-EUSO

BUT

Lack of reliable hadronic interaction models,which are needed for a detailed

interpretation

Ralf Ulrich 5

Energy Flux

Energy (eV/particle)

1310 1410 1510 1610 1710 1810 1910 2010

)1.

5 e

V-1

sr

-1 s

ec-2

J(E

) (

m2.

5S

cale

d flu

x E

1310

1410

1510

1610

1710

1810

1910

(GeV)ppsEquivalent c.m. energy 210 310 410 510 610

RHIC (p-p)

-p)γHERA (

Tevatron (p-p)LHC (p-p)

ATIC

PROTON

RUNJOB

KASCADE (QGSJET 01)

KASCADE (SIBYLL 2.1)KASCADE-Grande (prel.)

Tibet ASg (SIBYLL 2.1)

HiRes-MIA

HiRes I

HiRes IIAuger SD 2008

LHC

Auger

Ralf Ulrich 6

Physics of the Knee

◮ Astrophysical scenarios: Eknee ∝ Z

◮ Particle physics: Eknee ∝ A⇒>20% of missing energy at LHC ...

Ralf Ulrich 7

Physics of the Knee

◮ Astrophysical scenarios: Eknee ∝ Z

◮ Particle physics: Eknee ∝ A⇒>20% of missing energy at LHC ...

Ralf Ulrich 7

Physics of the Knee

◮ Astrophysical scenarios: Eknee ∝ Z

◮ Particle physics: Eknee ∝ A⇒>20% of missing energy at LHC ...

Ralf Ulrich 7

Physics of the Knee

◮ Astrophysical scenarios: Eknee ∝ Z

◮ Particle physics: Eknee ∝ A⇒>20% of missing energy at LHC ...

Ralf Ulrich 7

Longitudinal Profiles

]2Depth [g/cm

300 400 500 600 700 800 900 1000

]2E

nerg

y de

posi

t [P

eV/g

/cm

0

2

4

6

8

10

12

14

16

18

20

Auger event

Height a.s.l. (m)60008000100001200014000

E ∼ 1019 eV

Ralf Ulrich 8

Longitudinal Profiles

]2Depth [g/cm

300 400 500 600 700 800 900 1000

]2E

nerg

y de

posi

t [P

eV/g

/cm

0

2

4

6

8

10

12

14

16

18

20Auger event

Iron

Height a.s.l. (m)60008000100001200014000

E ∼ 1019 eV

Ralf Ulrich 8

Longitudinal Profiles

]2Depth [g/cm

300 400 500 600 700 800 900 1000

]2E

nerg

y de

posi

t [P

eV/g

/cm

0

2

4

6

8

10

12

14

16

18

20Auger event

Nitrogen

Height a.s.l. (m)60008000100001200014000

E ∼ 1019 eV

Ralf Ulrich 8

Longitudinal Profiles

]2Depth [g/cm

300 400 500 600 700 800 900 1000

]2E

nerg

y de

posi

t [P

eV/g

/cm

0

2

4

6

8

10

12

14

16

18

20Auger event

Proton

Height a.s.l. (m)60008000100001200014000

E ∼ 1019 eV

Ralf Ulrich 8

Average Xmax

18 18.5 19 19.5 20

]2>

[g

/cm

max

<X

650

700

750

800

850

Energy [eV]

1810 1910 2010

SIBYLL 2.1QGSJet01cQGSJetII.3EPOS 1.61

Auger (PRL 2010)

HiRes (PRL 2010)

proton

iron

Ralf Ulrich 9

Fluctuations of Xmax

17.5 18 18.5 19 19.5 20

]2)

[g

/cm

max

RM

S(X

10

20

30

40

50

60

70

80

90

Energy [eV]

1810 1910 2010

proton

iron

Auger (PRL 2010)

SIBYLLQGSJetQGSJetIIEPOS

⇒ Strong trend to reduced fluctuations at high energyRalf Ulrich 10

Hadronic Interactions – Cosmic Ray-Air Cross Section

Limit: no fluctuation in the air shower after firstinteraction

σcr−air =〈m〉

RMS(X1)>

〈m〉RMS(Xmax)

(Energy/eV)10

log11 12 13 14 15 16 17 18 19 20

Cro

ss s

ectio

n

[mb]

400

600

800

1000

1200

1400

proton

QGSJET01cNEXUS 3.96SIBYLL 2.1QGSJETII.3

helium

oxygen

Energy [eV]1110 1210 1310 1410 1510 1610 1710 1810 1910 2010

[GeV]ppsEquivalent c.m. energy 210 310 410 510

)max

Lower limit from Auger RMS(X

Tevatron

LHC

Accelerator data (p−p) + Glauber

Ralf Ulrich 11

Extensive Air Showers and Hadronic Interactions

Extended Heitler Model

n=1

n=2

n=3

charged neutral

primary

+ -o

IX

Shower maximum

Xmax ≈ λI + X0 lnE0

Nmult E e.m.crit

Muon number at observationlevel

Nµ = Nπ± =

(

E0

E Icrit

)β

where

β = ln(

23 Nmult

)

/ ln (Nmult) ≈ 0.9

(J. Matthews, APP 22 (2005) 387)

Ralf Ulrich 13

Beyond the Heitler Model ...

◮ Cross Section: λ

◮ Multiplicity: nmult

◮ Elasticity: kela = Emax/Etot

◮ Charge ratio: c = nπ0/(nπ0 + nπ− + nπ+)

◮ Nuclear primary: A

Ralf Ulrich 14

Analysis of Cosmic Ray Data

KASCADE - Electron/Muon-Frequencies

i2 χD

evia

tion

0

2

4

6

8

10

12

14

tr.µlg N

4 4.5 5 5.5 6 6.5

elg

N

5

5.5

6

6.5

7

7.5

8

i2 χD

evia

tion

0

2

4

6

8

10

12

14

tr.µlg N

4 4.5 5 5.5 6 6.5

elg

N

5

5.5

6

6.5

7

7.5

8

(KASCADE, APP:24 1 (2005), astro-ph/0505413)Ralf Ulrich 16

Pierre Auger Observatory: Xmax vs. Muons

18 18.5 19 19.5 20

]2>

[g

/cm

max

<X

650

700

750

800

850

Energy [eV]

1810 1910 2010

SIBYLL 2.1QGSJet01cQGSJetII.3EPOS 1.61

Auger (PRL 2010)

HiRes (PRL 2010)

proton

iron

]2DX [g/cm0 200 400 600 800 1000 1200 1400 1600 1800 2000

[VE

M]

µS

0

5

10

15

20

25

30

(Energy scale: +26%)

DX=Xobs − Xmax

Muonsignalat1000m

proton

iron

data > 60deg

data < 60deg

(Auger/HiRes Xmax: PRL 2010,

Muons: e.g. ICRC 2007, arXiv:0706.1921 [astro-ph])

Ralf Ulrich 17

Cosmic Ray Analysis/Modeling Uncertainties

Modeling UncertaintiesCross Section Multiplicity

(Energy/eV)10

log13 14 15 16 17 18 19 20

Cro

ss s

ectio

n (p

roto

n−ai

r)

[mb]

200

300

400

500

600

700

800

QGSJET01cEPOS 1.61SIBYLL 2.1QGSJETII.3

Energy [eV]1310 1410 1510 1610 1710 1810 1910 2010

[GeV]ppsEquivalent c.m. energy 310 410 510

TevatronLHC

accelerator data (p−p) + Glauber

(E/eV)10

log11 12 13 14 15 16 17 18 19 20

Mul

tiplic

ity

0

500

1000

1500

2000

2500

3000

Energy [eV]

1110 1210 1310 1410 1510 1610 1710 1810 1910 2010

Elasticity

total / EmaxE0 0.2 0.4 0.6 0.8 1

prob

abili

ty

0

0.01

0.02

0.03

0.04

0.05

0.06

eV19EPOS, protons at 10eV19QGSJET, protons at 10

eV19QGSJETII, protons at 10eV19SIBYLL, protons at 10eV19NEXUS, protons at 10

Ralf Ulrich 19

Estimate Importance On Air Shower Interpretation

Modify specific features of hadronic interactions during air showerMonte-Carlo simulation:

◮ Assume logarithmically growing deviation from original modelprediction above 1015 eV.

◮ Below 1015 eV the original model is used.

◮ The parameter f19 denotes the nominal deviation at 1019 eV.

αmodified(E) = α

HE−model(E) ·(

1 + (f19 − 1) · log10(E/1 PeV)log10(10EeV/1PeV)

)

Where α can be:◮ Cross Section: σprod

had◮ Multiplicity: nmult

◮ Elasticity: kela = Eleading/Emax

◮ Pion-Charge Ratio: c = nπ0/(nπ0 + nπ+ + nπ−)

(R. Ulrich et al., submitted to PRD, arXiv 1010.4310 [hep-ph])

Ralf Ulrich 20

Estimate Importance On Air Shower Interpretation

Modify specific features of hadronic interactions during air showerMonte-Carlo simulation:

◮ Assume logarithmically growing deviation from original modelprediction above 1015 eV.

◮ Below 1015 eV the original model is used.

◮ The parameter f19 denotes the nominal deviation at 1019 eV.

αmodified(E) = α

HE−model(E) ·(

1 + (f19 − 1) · log10(E/1 PeV)log10(10EeV/1PeV)

)

Where α can be:◮ Cross Section: σprod

had◮ Multiplicity: nmult

◮ Elasticity: kela = Eleading/Emax

◮ Pion-Charge Ratio: c = nπ0/(nπ0 + nπ+ + nπ−)

(R. Ulrich et al., submitted to PRD, arXiv 1010.4310 [hep-ph])

Ralf Ulrich 20

Results for 〈Xmax〉

Proton Iron

19f0.2 0.3 0.4 1 2 3 4 5 6

]2

[g/c

mm

axM

ean

X

700

750

800

850

900

19f0.2 0.3 0.4 1 2 3 4 5 6

]2

[g/c

mm

axM

ean

X

700

750

800

850

900

◮ 〈Xmax〉 can be shifted significantly

◮ Data are suggesting◮ Intermediate mass, mixed composition, or:◮ Large cross section for a proton dominated composition◮ Small cross section for a iron dominated composition

Ralf Ulrich 21

Results for 〈Xmax〉

Proton Iron

19f0.2 0.3 0.4 1 2 3 4 5 6

]2

[g/c

mm

axM

ean

X

700

750

800

850

900

19f0.2 0.3 0.4 1 2 3 4 5 6

]2

[g/c

mm

axM

ean

X

700

750

800

850

900Auger dataHiRes data

◮ 〈Xmax〉 can be shifted significantly

◮ Data are suggesting◮ Intermediate mass, mixed composition, or:◮ Large cross section for a proton dominated composition◮ Small cross section for a iron dominated composition

Ralf Ulrich 21

Results for RMS(Xmax)

Proton Iron

19f0.2 0.3 0.4 1 2 3 4 5 6

]2

[g/c

mm

axR

MS

X

20

40

60

80

100

19f0.2 0.3 0.4 1 2 3 4 5 6

]2

[g/c

mm

axR

MS

X

20

40

60

80

100

◮ RMS(Xmax) mostly impacted by cross section, and elasticity

◮ Iron induced showers very robust

◮ Auger data only marginally compatible with protons in a high crosssection scenario

Ralf Ulrich 22

Results for RMS(Xmax)

Proton Iron

19f0.2 0.3 0.4 1 2 3 4 5 6

]2

[g/c

mm

axR

MS

X

20

40

60

80

100Auger data

19f0.2 0.3 0.4 1 2 3 4 5 6

]2

[g/c

mm

axR

MS

X

20

40

60

80

100

◮ RMS(Xmax) mostly impacted by cross section, and elasticity

◮ Iron induced showers very robust

◮ Auger data only marginally compatible with protons in a high crosssection scenario

Ralf Ulrich 22

Results for Muon Numbers

Proton Iron

19f0.2 0.3 0.4 1 2 3 4 5 6

QG

SII

µ/N µ

Rel

ativ

e N

0.8

1

1.2

1.4

1.6

19f0.2 0.3 0.4 1 2 3 4 5 6

QG

SII

µ/N µ

Rel

ativ

e N

0.6

0.8

1

1.2

1.4

1.6

cross sectionmultiplicityelasticitycharge ratio

◮ Multiplicity and Pion charge ratio are shifting model predictions

◮ Auger muon data incompatible with proton scenario

◮ Even for iron primaries: multiplicity must be high andpion-charge-ratio small

Ralf Ulrich 23

Results for Muon Numbers

Proton Iron

19f0.2 0.3 0.4 1 2 3 4 5 6

QG

SII

µ/N µ

Rel

ativ

e N

0.8

1

1.2

1.4

1.6

19f0.2 0.3 0.4 1 2 3 4 5 6

QG

SII

µ/N µ

Rel

ativ

e N

0.6

0.8

1

1.2

1.4

1.6

cross sectionmultiplicityelasticitycharge ratio

◮ Multiplicity and Pion charge ratio are shifting model predictions

◮ Auger muon data incompatible with proton scenario

◮ Even for iron primaries: multiplicity must be high andpion-charge-ratio small

Caution: Definition of Muon number is not identical, e.g.:

Auger measures at 1000m, Simulations give total muon number

Ralf Ulrich 23

LHC Data

as a benchmark for existing models

Rise of Secondary Multiplicity

(T. Pierog)

Ralf Ulrich 25

Rise of Secondary Multiplicity

(D. d’Enterria et al., to be published)

Ralf Ulrich 26

Multiplicity Distribution

(D. d’Enterria et al., to be published)

Ralf Ulrich 27

Pseudorapidity Distribution, NSD

(T. Pierog)

Ralf Ulrich 28

Pseudorapidity Distribution, INEL

(T. Pierog)

Ralf Ulrich 29

Average Transverse Momentum

(D. d’Enterria et al., to be published)Ralf Ulrich 30

Extrapolation to GZK Energies

(D. d’Enterria et al., to be published)

⇒ Data at 14TeV are mandatory

Ralf Ulrich 31

Interactions with Nuclei/Air

(T. Pierog)

Air Showers: p-Air, A-Air, π-Air, ...

⇒ not just p-p, but nuclei and nuclei combinations

Ralf Ulrich 32

Forward Detectors

(TOTEM, ZDC, CASTOR)

Forward Detectors

ηPseudorapidity -10 -5 0 5 10

[G

eV]

ηE

nerg

y flo

w d

E/d

0

200

400

600

800

1000

1200

1400

1600

1800 CMS HFCASTOR ZDC

Model predictions

⇒ Crucial for air showers is particle production in forward direction!

Ralf Ulrich 34

Predicted Particle Production in Forward Direction

[GeV]hadE0 1000 2000 3000 4000 5000 6000 7000

had

dP/d

E

0

0.0002

0.0004

0.0006

0.0008

0.001

0.0012CASTOR (hadrons)

SIBYLL

QGSJET

EPOS

QGSJETII

[GeV]hadE0 2000 4000 6000 8000 10000

had

dP/d

E

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5-310×

ZDC (hadrons)

chN0 10 20 30 40 50 60

chdP

/dN

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

TOTEM T2

(

Ralf Ulrich 35

Impact of Modified Multiplicity

[GeV]hadE0 1000 2000 3000 4000 5000 6000 7000

had

dP/d

E

0

0.0002

0.0004

0.0006

0.0008

0.001

CASTOR (hadrons)SIBYLL, standard

2×eV)19(10mult

SIBYLL, n

0.5×eV)19(10mult

SIBYLL, n

[GeV]hadE0 2000 4000 6000 8000 10000

had

dP/d

E

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5-310×

ZDC (hadrons)

chN0 10 20 30 40 50 60

chdP

/dN

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

TOTEM T2

(cf. Ulrich et al., submitted, arXiv:1010.4310v1 [hep-ph])

Ralf Ulrich 36

Impact of Modified Elasticity

[GeV]hadE0 1000 2000 3000 4000 5000 6000 7000

had

dP/d

E

0

0.0002

0.0004

0.0006

0.0008

0.001

0.0012CASTOR (hadrons)

SIBYLL, standard

0.6×eV)19(10ela

SIBYLL, k

0.2×eV)19(10ela

SIBYLL, k

[GeV]hadE0 2000 4000 6000 8000 10000

had

dP/d

E

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5-310×

ZDC (hadrons)

chN0 10 20 30 40 50 60

chdP

/dN

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

TOTEM T2

(cf. Ulrich et al., submitted, arXiv:1010.4310v1 [hep-ph])

Ralf Ulrich 37

Potential Impact of LHC on

Interpretation of EAS Data

At the example of a precise measurement of the elasticity andCASTOR

Relevance of CASTOR for Cosmic Ray Interpretation

Size

Heig

ht

air shower

X max

CASTOR

E [GeV]ΣTotal Energy 0 1000 2000 3000 4000 5000 6000 7000

EΣdP

/d

0

0.0002

0.0004

0.0006

0.0008

0.001

0.0012

SIBYLL, original

0.6×eV) 19SIBYLL, elasticity(10

0.2×eV) 19SIBYLL, elasticity(10

18 18.5 19 19.5 20

]2>

[g

/cm

max

<X

650

700

750

800

850

Energy [eV]

1810 1910 2010

SIBYLL, original 0.6×eV) 19SIBYLL, elasticity(10 0.2×eV) 19SIBYLL, elasticity(10

SIBYLL, original 0.6×eV) 19SIBYLL, elasticity(10 0.2×eV) 19SIBYLL, elasticity(10

Auger (PRL 2010)

proton, SIBYLL

iron, SIBYLL

Ralf Ulrich 39

Impact of Elasticity / Leading Particles

18 18.5 19 19.5 20

]2>

[g

/cm

max

<X

650

700

750

800

850

Energy [eV]

1810 1910 2010

Auger (PRL 2010)

proton, SIBYLL

iron, SIBYLL

Without LHC

◮ Precise measurement of elasticity at 300GeV

◮ Extrapolation uncertainty grows by 10% per decade in energy

Ralf Ulrich 40

Impact of Elasticity / Leading Particles

18 18.5 19 19.5 20

]2>

[g

/cm

max

<X

650

700

750

800

850

Energy [eV]

1810 1910 2010

Auger (PRL 2010)

proton, SIBYLL

iron, SIBYLL

With LHC

◮ Precise measurement of elasticity at 14TeV

◮ Extrapolation uncertainty grows by 10% per decade in energy

Ralf Ulrich 40

Summary

◮ High energy models need tuning to data as close to the phase spacerelevant in air showers as possible

◮ Interaction characteristics has impact on air shower observables onthe same order of magnitude as as primary mass composition

⇒ Almost impossible to “measure” mass composition from air shower

observables in the moment

◮ If cosmic ray mass composition is constrained⇒ Air shower data sensitive to interaction physics up to ∼ 300TeV

So far:

◮ LHC data is well bracketed by cosmic ray models

◮ Cosmic ray community needs the data at 14TeV and high η

OutlookHelmholtz Young Investigator Group at KIT:CMS forward physics / Pierre Auger Observatory