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Takashi SAKO

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.

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Takashi SAKO

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  1. 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 IV Workshop on Air Shower Detection at High Altitude@Napoli

  2. 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 IV Workshop on Air Shower Detection at High Altitude@Napoli

  3. 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

  4. CR and Interaction

  5. Uncertainty in hadronic interaction 0g/cm2 Xmax PROTON Deep in the atmosphere IRON Proton shower and nuclear shower of same total energy 1018 1019 Pierre Auger Observatory Players: EPOS, QGSJET, SIBYLL, DPMJET models

  6. Lower energy also… QGS1 QGSII SIBYLL EPOS (Kampert and Unger, Astropart. Phys., 2012)

  7. Collider observables

  8. What to be measured at accelerators? 1. Inelastic cross section （interaction mean free path） Note: √s=14TeV <=> Elab=1017eV 2. Particle production Multi meson production Leading baryons π- π+ inelasticity (Emeson/E0= 1-elasticity) multiplicity meson spectrum elasticity (Ebaryon/E0) baryon spectrum π0 3. Nuclear effect γ proton / neutron

  9. Where to be measured at colliders?multiplicity and energyflux at LHC 14TeV collisionspseudo-rapidity; η= -ln(tan(θ/2)) Multiplicity Energy flux All particles neutral Most of the particles produced into central, Most of the energy flows intoforward

  10. Before LHC result @ 7TeV After LHC R.Ulrichet al., PRD, 83 (2011) 054026 The TOTEM Collaboration, CERN-PH-EP-2012-353

  11. multiplicity@central D.D’Enterriaet al., Astropart. Phys., 35 (2011) 98-113

  12. Forward Energy Flow(Hadronic Forward Calorimeter) The CMS Collaboration, JHEP, 11 (2011) 148

  13. LHCf

  14. The LHCfcollaboration • 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.MenjoKobayashi-Maskawa Institute, Nagoya University, Japan • K.YoshidaShibaura Institute of Technology, Japan • K.Kasahara, Y.Shimizu, T.Suzuki, S.Torii • Waseda University, Japan • T.TamuraKanagawa University, Japan • M.HaguenauerEcolePolytechnique, France • W.C.TurnerLBNL, Berkeley, USA • O.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, P.Papini, S.Ricciarini, G.Castellini • INFN, Univ. di Firenze, Italy • A.TricomiINFN, Univ. di Catania, Italy • J.Velasco, A.FausIFIC, Centro Mixto CSIC-UVEG, Spain • A-L.Perrot, D.Pfeiffer CERN, Switzerland

  15. ATLAS The LHC forward experiment LHCfArm#1 140m Two independent detectors at either side of IP1(Arm#1, Arm#2 ) Beam LHCfArm#2 Charged particles(+) 96mm Beam pipe Neutral particles Charged particles(-) • All charged particles are swept by dipole magnet • Neutral particles (photons and neutrons) arrive at LHCf • 0 degree is covered

  16. Arm#1 Detector 20mmx20mm+40mmx40mm 4 XY SciFi+MAPMT Arm#2 Detector 25mmx25mm+32mmx32mm 4 XY Silicon strip detectors LHCfDetectors • 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

  17. Which E-pT range LHCf sees ? photons π0 (Arm1) pp 7TeV, EPOS

  18. Summary of 2009-2010 run and current status • With Stable Beams at √s = 900 GeV • Total of 42 hours for physics • About 105shower events in Arm1+Arm2 • With Stable Beams at √s = 7 TeV (Elab = 2.5x1016eV) • 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 • ~ 4x108shower events in Arm1+Arm2 • ~ 106π0events 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

  19. Observed event Longitudinal development Energy & PID Position & multihit ID Lateral development Silicon X Silicon Y

  20. Particle Identification Hadron event Photon event + ; data Histograms; MC 90% (L90% indicates the depth of shower) (Adriani et al., PLB, 2011)

  21. Photon spectra @ 7TeV (Data vs. Models) Adriani et al., PLB, 703 (2011) 128-134 Around 0 degree (On axis) Off axis DPMJET 3.04 QGSJET II-03 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145

  22. Photon spectra @ 900GeV Adriani et al., PLB, 715 (2012) 298-303

  23. 900GeV vs. 7TeV XF spectra : 900GeV data vs. 7TeV data LHCf coveragein XF-pT plane (XF = E/Ebeam) Preliminary Data 2010 at √s=900GeV (Normalized by the number of entries in XF > 0.1)Data 2010 at √s=7TeV (η>10.94) 900GeVvs. 7TeVwith the same PT region small-η = Large tower 900 GeV Small+large tower big-η =Small tower • Normalized by # of evnetsXF > 0.1 • Statistical error only Good agreement of XF spectrum shape between 900 GeV and 7 TeV.

  24. π0 analysis γ1(E1) • π0 candidate • 599GeV &419GeV photonsin 25mm and 32mm tower, respectively • M = θ√(E1xE2) R 140m Longitudinal development θ Large Cal. Small Cal. γ2(E2) I.P.1 Lateral development Silicon X Silicon Y

  25. π0pT distributionin different rapidity (y) ranges Adriani et al., PRD, 86, 092001 (2012)

  26. π0 <PT> ybeam - y <pT> comparison with UA7 at 630GeV (Pare et al., PLB, 242, 531 (1990))

  27. Playing a game with air shower (effect of forward meson spectra) • 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 pT E1 E2 E=E1+E2 xF = E/E0 xF = E/E0

  28. An example of filtering DPMJET3+filter photon spectrum ~30g/cm2 π0 spectrum 2.5x1016eV proton

  29. 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

  30. Neutron Spectra at 7TeV pp(models) Model predictions Model predictions smeared by the LHCf energy resolution

  31. p-Pb collisions Neutron spectrum at the p remnant (energy resolution taken into account) Photon spectrum at the p remnant • 1st collider experiment pA (dA done at RHIC) • LHCf triggers ATLAS to take common events with central

  32. What to be measured at accelerators? 1. Inelastic cross section （interaction mean free path） Note: √s=14TeV <=> Elab=1017eV 2. Particle production Multi meson production Leading baryons π- π+ inelasticity (Emeson/E0= 1-elasticity) multiplicity meson spectrum elasticity (Ebaryon/E0) baryon spectrum π0 3. Nuclear effect γ proton / neutron

  33. Summary • 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…

  34. Cosmic-ray spectrum & Colliders Knee: end of galactic proton CR End of galactic CR and transition to extra-gal CR Ankle (GZK) cutoff: end of CR spectrum 1010 1020 eV ISR RHIC SppS Tevatron LHC 14TeV LHC 7 TeV LHC 0.9TeV Perfect (or best at least) understanding up to 1017eV helps CR physics

  35. Backup

  36. n, gamma LHCｆカロリーメータ構造 • 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

  37. η θ [μrad] η=8.40 8.7 310 η=8.40 η=8.77 η=8.77 ∞ 0 Rapidity vs Forward energy spectra Viewed from IP1 (red:Arm1, blue:Arm2) Projected edge of beam pipe

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