LHCf and Cosmic-Rays

LHCf and Cosmic-Rays
Ralf Ulrich, KIT
Catania, 07/2011
Astrophysics at LHC
Ralf Ulrich - 1
Astrophysics at LHC – Air-Showers + Forward Physics
Ralf Ulrich - 1
Particle Accelerators: Man-Made versus Cosmic Rays
Large Hadron Collider (LHC)
Acceleration to 7 TeV
Ultra-High Energy Cosmic Rays
Acceleration to > 100.000.000 TeV
Fundamental physics in
extreme environments at
extreme energies
Interactions at 14 TeV
Interactions up to ∼ 300 TeV
Ralf Ulrich - 2
Cosmic-Ray Overview
7
Ralf Ulrich - 3
Cosmic-Ray Overview
7
Ralf Ulrich - 4
Characterisation of Current Situation
Large amounts of high quality cosmic ray data
Auger, HiRes, AGASA, TA, Future: JEM-EUSO, ...
BUT
Lack of reliable hadronic interaction models,
which are needed for a detailed
interpretation
Ralf Ulrich - 5
Status of Ultra-High Energy Cosmic Ray Observations
1015
Flux × E
2.5
Flux ∝ E-2.5
1014
Auger 2009 / 2010
18
18.5
19
Suppression at 1019.7 eV
observed with > 20 σ with
large statistics
Composition unclear
19.5
20
800
<Xmax>
on
prot
750
700
iron
18
10
19
10
20
10
log (E/eV)
10
Pierre Auger Collaboration: PRL 2010, PLB 2010
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Interactions in Air Showers
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DC
,Z
Cf
LH
SIBYLL
EPOS 1.99
QGSJet
1200
QGSJetII
1000
0.0016
EPOS 1.99
CASTOR
0.0012
QGSJet
QGSJetII
0.001
0.0008
600
0.0006
400
0.0004
0
SIBYLL
0.0014
800
200
0.0002
-10
-5
0
5
0
0
10
η
dN/dEπ0 [1/GeV]
[1/GeV]
2
S
,T
LA
HF
AT
OR HF
S,
ST al,
al,
FC T2
CM
CA FC
had
LH
DC
,Z
Cf
1400
∑E
1600
dN/d
dE/dη [GeV]
LHC and Cosmic-Ray Models
500
1000
1500
2000
2500
3000
∑E
3500
[GeV]
had
SIBYLL
EPOS
10-4
LHCf
QGSJet
QGSJetII
10-5
10-6
10-7
0
1000
2000
3000
4000
5000
6000
7000
Eπ0 [GeV]
Model differences in the
forward direction
Importance of forward
direction for air-showers
Missing data to validate
models
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Potential Impact
[g/cm2]
850
Without LHC
800
YLL
IB
n, S
proto
<Xmax>
<Xmax>
[g/cm2]
Significantly reduced extrapolation uncertainty in cosmic-ray
analyses
750
700
850
800
700
YLL
Auger (PRL 2010)
650
1818
10
L
IBYL
n, S
proto
750
, SIB
iron
With LHC
18.5
1919
10
19.5
Energy
2020
10
YLL
, SIB
650
iron
1818
10
Auger (PRL 2010)
18.5
1919
10
[eV]
19.5
2020
10
Energy
[eV]
Assumptions: Elasticity=Emax /Etot is measured to high accuracy at 400 GeV (left panel) and 14 TeV (right panel).
The uncertainty of the extrapolation beyond these measurements increases by 10 % per decade in energy
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Extended Heitler Model
Shower maximum
primary
n=1
charged
XI
neutral
Xmax ≈ λI + X0 ln
E0
e.m.
Nmult Ecrit
Muon number at observation level
n=2
+ -
Nµ = Nπ ± =
o
n=3
E0
I
Ecrit
β
where
β = ln 23 Nmult / ln (Nmult ) ≈ 0.9
(J. Matthews, APP 22 (2005) 387)
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Beyond the Heitler Model ...
Cross Section: λ
Multiplicity: nmult
Ratio of energy going into e.m. particles:
re.m. = Ee.m./Etot
Charge ratio: c = nπ0 /(nπ0 + nπ− + nπ+ )
Elasticity: kela = Emax /Etot
Particle Spectra
Nuclear primaries: A
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Air Shower Monte-Carlo
Modify specific features of hadronic
interactions during air shower Monte-Carlo
simulation:
Assume logarithmically growing
deviation from original model
prediction above Ethreshold .
Below Ethreshold the original model is
used.
The parameter f19 denotes the nominal
deviation at 1019 eV.
αmodified (E) = αorig (E) · 1 + (f19 − 1) ·
log 10 (E/1015 eV)
log10 (1019 eV/1015 eV)
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Model Extrapolations
Cross section (proton−air) [mb]
Equivalent c.m. energy spp
103
102
700
[GeV]
105
104
Tevatron
LHC
600
accelerator data (p−p) + Glauber
500
400
300
SIBYLL 2.1
SIBYLL 2.1, f 19 = 1.2
SIBYLL 2.1, f 19 = 0.8
200
1111
10
1212
10
1313
10
1414
10
1515
10
• Ethreshold = 1015 eV
• Modified proton-air cross section
1616
10
1717
10
1818 10
1919 10
2020
10
log (Energy/eV)
10
Energy
[eV]
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Example: Modify Secondary Multiplicity
Resampling of secondaries after each hadronic interaction
Duplication or deletion of secondary particles
Conserve: Energy, Charge, Relative energy in particle type groups
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[g/cm2 ]
880
860
RMS Xmax
Mean Xmax
[g/cm2 ]
Impact of Multiplicity on Xmax
840
820
800
80
75
70
65
60
780
55
760
50
740
720
45
1
Multiplicity f
1
19
Multiplicity f
19
Significant impact on hXmax i
No change of fluctuations
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Modified Charge-Ratio
c = nπ0 /(nπ0 + nπ− + nπ+ )
Switch between pion types: π 0 ↔ π ±
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[g/cm2 ]
840
830
RMS Xmax
Mean Xmax
[g/cm2 ]
Impact of Pion Charge Ratio on Xmax
820
810
70
65
60
55
800
50
790
1
Charge−ratio f
19
1
Charge−ratio f
19
Shifting of hXmax i
No change of fluctuations
Ralf Ulrich - 17
10
-3
10
-4
10
-5
10
-6
LHCf s=7TeV
Gamma-ray like
°
η > 10.94, ∆φ = 360
Events/Nine/GeV
Events/Nine/GeV
Measurement of Forward Spectra
10-7
10
-8
10
-9
10
-3
10-4
10
-5
10
-6
°
10-7
Data 2010,
∫ Ldt=0.68+0.53nb
-1
10
-8
10
-9
QGSJET II-03
∫ Ldt=0.68+0.53nb
-1
DPMJET 3.04
QGSJET II-03
SIBYLL 2.1
EPOS 1.99
-10
Data 2010,
Data 2010, Stat. + Syst. error
DPMJET 3.04
SIBYLL 2.1
10
PYTHIA 8.145
MC/Data
MC/Data
Gamma-ray like
8.81 < η < 8.99, ∆φ = 20
Data 2010, Stat. + Syst. error
10
LHCf s=7TeV
2.5
2
1.5
-10
EPOS 1.99
PYTHIA 8.145
2.5
2
1.5
1
1
0.5
0.5
0
500
1000
1500
2000
2500
3000
3500
Energy[GeV]
0
500
1000
1500
2000
2500
3000
3500
Energy[GeV]
What does it mean?
What is the impact?
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Modifying Forward Spectra
Entries
Preliminary
LHCf Data
Exponential Spectrum
Modified Spectrum, 1.4
10-6
Modified Spectrum, 0.6
10-7
500
Eimod
1000
=
1500
P
Pj
j
Eiorg
Ejmod
2000
2500
Energy / GeV
Eiorg × (Eiorig )−f19
Ralf Ulrich - 19
[g/cm2 ]
[g/cm2 ]
Impact of Forward Spectra on Xmax
830
Preliminary
58
RMS Xmax
Mean Xmax
56
820
810
54
52
800
50
790
48
780
0.4
0.5
0.6
0.7 0.8 0.9 1
2
π -spectrum f 19
0
0.4
0.5
0.6
0.7 0.8 0.9 1
2
π0-spectrum f 19
Shifting of hXmax i
Change of fluctuations
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Impact on Air-Shower Interpretation
Preliminary
CAVEATS
Choice of Ethreshold
Pion spectra vs. Photon spectra
Relation of f19 to LHCf data
Ralf Ulrich - 21
High-Energy Physics with Cosmic-Ray Data
Elementary High-Energy Physics with Cosmic Rays
⇒ Inelastic Proton-Proton Cross-Section at
√
s = 57 TeV
OBSERVATORY
images/protonProtonInel.eps
Just about to be published by the Pierre Auger Collaboration.
(Not yet public!)
Ralf Ulrich - 23
Summary
Forward data at LHC are crucial for
cosmic-ray interpretation
The phase-space with high energy flow
is most important
LHCf results are important for
cosmic-ray interpretation, but details
are not fully investigated yet
LHC and cosmic rays: not a one-way
road
Cosmic ray data can be used to
extend some individual observations
to higher energies