Forward particle production measured by LHCf;
testing hadronic interaction models for CR physics
Takashi SAKO(Solar-Terrestrial environment Laboratory/Kobayashi-
Maskawa Institute, Nagoya University, Japan)On behalf of the LHCf Collaboration
11-Feb-2013 IV Workshop on Air Shower Detection at High Altitude@Napoli
Forward particle production measured by LHCf;
testing hadronic interaction models for CR physics
Takashi SAKO(Solar-Terrestrial environment Laboratory/Kobayashi-
Maskawa Institute, Nagoya University, Japan)On behalf of the LHCf Collaboration
21-Feb-2013 IV Workshop on Air Shower Detection at High Altitude@Napoli
Outline
• Quick reminder for the CR and interaction• Important collider observables• The LHCf experiment
– Experimental setup and status– Results from 900GeV and 7TeV p-p collisions– Impact on air shower– Future
• Summary
3
CR and Interaction
4
5
Uncertainty in hadronic interaction
PROTON
IRON
10191018
0g/cm2
Xmax
Proton shower and nuclear shower of same total energy
Pierre Auger Observatory
Deep in the atmosphere
Players: EPOS, QGSJET, SIBYLL, DPMJET models
6(Kampert and Unger, Astropart. Phys., 2012)
Lower energy also… QGS1 QGSII
SIBYLL EPOS
Collider observables
7
8
Leading baryons Multi meson production
What to be measured at accelerators?
proton / neutron
π0
π+
π-
γ
1. Inelastic cross section( interaction mean free path)
3. Nuclear effect
elasticity (Ebaryon/E0)baryon spectrum
inelasticity (Emeson/E0= 1-elasticity)multiplicitymeson spectrum
2. Particle production
Note: √s=14TeV <=> Elab=1017eV
Where to be measured at colliders?multiplicity and energy flux at LHC 14TeV collisions
pseudo-rapidity; η= -ln(tan(θ/2))
Multiplicity Energy flux
All particles
neutral
Most of the particles produced into central,Most of the energy flows into forward 9
10
result @ 7TeV
The TOTEM Collaboration, CERN-PH-EP-2012-353
R.Ulrich et al., PRD, 83 (2011) 054026
Before LHC
After LHC
multiplicity@central
11
D.D’Enterria et al., Astropart. Phys., 35 (2011) 98-113
Forward Energy Flow (Hadronic Forward Calorimeter)
12The CMS Collaboration, JHEP, 11 (2011) 148
LHCf
13
T.Iso, Y.Itow, K.Kawade, Y.Makino, K.Masuda, Y.Matsubara, E.Matsubayashi, G.Mitsuka, Y.Muraki, T.Sako
Solar-Terrestrial Environment Laboratory, Nagoya University, Japan
H.Menjo Kobayashi-Maskawa Institute, Nagoya University, Japan K.Yoshida Shibaura Institute of Technology, JapanK.Kasahara, Y.Shimizu, T.Suzuki, S.Torii Waseda University, JapanT.Tamura Kanagawa University, JapanM.Haguenauer Ecole Polytechnique, FranceW.C.Turner LBNL, Berkeley, USAO.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, P.Papini, S.Ricciarini, G.Castellini INFN, Univ. di Firenze, ItalyA.Tricomi INFN, Univ. di Catania, Italy J.Velasco, A.Faus IFIC, Centro Mixto CSIC-UVEG, SpainA-L.Perrot, D.Pfeiffer CERN, Switzerland
The LHCf collaboration
The LHC forward experiment
15
ATLAS
140m
LHCf Arm#1
LHCf Arm#2
Two independent detectors at either side of IP1 (Arm#1, Arm#2 )
Charged particles (+)Beam
Charged particles (-)
Neutral particles
Beam pipe
96mm
• All charged particles are swept by dipole magnet• Neutral particles (photons and neutrons) arrive at LHCf• 0 degree is covered
LHCf Detectors
Arm#1 Detector20mmx20mm+40mmx40mm4 XY SciFi+MAPMT
Arm#2 Detector25mmx25mm+32mmx32mm4 XY Silicon strip 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
16
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Which E-pT range LHCf sees ?
pp 7TeV, EPOS
photons p0 (Arm1)
Summary of 2009-2010 run and current status With Stable Beams at √s = 900 GeV
Total of 42 hours for physics About 105 shower events in Arm1+Arm2
With Stable Beams at √s = 7 TeV (Elab = 2.5x1016 eV) Total of 150 hours for physics with different setups
Different vertical position to increase the accessible kinematical range Runs with or without beam crossing angle
~ 4x108 shower events in Arm1+Arm2 ~ 106 π0 events in Arm1 and Arm2
Status Photon spectra at 900 GeV and 7 TeV, π0 spectra at 7TeV are
published Taking data at 4TeV/Z p-Pb collision NOW Upgrade to more rad-hard detectors for 14TeV in 2015 18
Observed event
Energy & PID
Position & multihit ID
Longitudinal development
Lateral development
Silicon X
Silicon Y
Particle Identification
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(L90% indicates the depth of shower)
Photon event Hadron event
(Adriani et al., PLB, 2011)
+ ; dataHistograms; MC
90%
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Photon spectra @ 7TeV (Data vs. Models)
DPMJET 3.04 QGSJET II-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145
Adriani et al., PLB, 703 (2011) 128-134Around 0 degree (On axis) Off axis
Photon spectra @ 900GeV
22
Adriani et al., PLB, 715 (2012) 298-303
small-η
= Large tower
big-η =Small tower
900GeV vs. 7TeV
Normalized by # of evnetsXF > 0.1 Statistical error only
XF spectra : 900GeV data vs. 7TeV data
Good agreement of XF spectrum shape between 900 GeV and 7 TeV.
Preliminary
Data 2010 at √s=900GeV(Normalized by the number of entries in XF > 0.1)Data 2010 at √s=7TeV (η>10.94)
LHCf coverage in XF-pT plane (XF = E/Ebeam)
900GeV vs. 7TeVwith the same PT region
900 GeV Small+large tower
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π0 analysis • π0 candidate• 599GeV & 419GeV photons in 25mm
and 32mm tower, respectively• M = θ√(E1xE2)
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Longitudinal development
Lateral development
Silicon X
Silicon Y
Small Cal.
LargeCal.
m 140= R
I.P.1θ
γ1(E1)
γ2(E2)
140mR
25
Adriani et al., PRD, 86, 092001 (2012)
π0 pT distribution in different rapidity (y) ranges
π0 <PT>
26<pT> comparison with UA7 at 630GeV (Pare et al., PLB, 242, 531 (1990))
ybeam - y
xF = E/E0
Playing a game with air shower (effect of forward meson spectra)
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• DPMJET3 always overpredicts production• Filtering DPMJET3 mesons
• according to an empirical probability function, divide mesons into two with keeping pT
• Fraction of mesons escape out of LHCf acceptance• This process
• Holds cross section• Holds elasticity/inelasticity• Holds energy conservation• Changes multiplicity• Does not conserve charge event-by-event
E=E1+E2
E1
E2
xF = E/E0
pT
An example of filtering
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π0 spectrum
photon spectrum
DPMJET3+filter
2.5x1016 eV proton
~30g/cm2
Future
• Neutron spectra in 7TeV p-p … analysis on going• 4TeV/Z p-Pb … data taking on going• Joint analysis with ATLAS … data ready• 14 TeV p-p in 2015 … detector upgrade on going• Light nuclei at LHC, RHIC??? … possibility in discussion
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Neutron Spectra at 7TeV pp(models)
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Model predictions
Model predictions smeared by the LHCf energy resolution
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p-Pb collisionsPhoton spectrum at the p remnant
Neutron spectrum at the p remnant(energy resolution taken into account)
• 1st collider experiment pA (dA done at RHIC)• LHCf triggers ATLAS to take common events with central
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Leading baryons Multi meson production
What to be measured at accelerators?
proton / neutron
π0
π+
π-
γ
1. Inelastic cross section( interaction mean free path)
3. Nuclear effect
elasticity (Ebaryon/E0)baryon spectrum
inelasticity (Emeson/E0= 1-elasticity)multiplicitymeson spectrum
2. Particle production
Note: √s=14TeV <=> Elab=1017eV
Summary
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Experiments at LHC provide useful data to calibrate CR interaction models
LHCf is a dedicated experiment to measure forward particles effective to the air shower development
LHCf completed operation at 900GeV and 7TeV p-p collisions and published photon and π0 spectra
None of the models perfectly describe the LHCf results, but models well bracket the experiment (this is generally true for the other LHC results).
No sizable collision energy dependence is so far found Forward meson spectra is effective in <Xmax> LHCf is proceeding more analysis, takes more data with
p-Pb collisions and 14TeV p-p collisions, and more…
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Cosmic-ray spectrum & Colliders
LHC
14T
eV
Teva
tron
LHC
0.9
TeV
LHC
7 Te
V
SppS
RHIC
ISR
1010 1020 eV
Knee: end of galactic proton CR
End of galactic CR and transition to extra-gal CR
Ankle (GZK) cutoff: end of CR spectrum
Perfect (or best at least) understanding up to 1017eV helps CR physics
Backup
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LHCfカロリーメータ構造n, gamma
• 全発光量からエネルギーを、形状から粒子を判定• <7TeVの入射粒子に対して、(特に電磁)シャワーは理解されている
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Rapidity vs Forward energy spectra
η=8.40
η=8.77 η=8.40
η=8.77
η
∞8.7
θ[μrad]
0
310
Projected edge of beam pipe
Viewed from IP1(red:Arm1, blue:Arm2)