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Latest results from LHCf on very forward particle production at LHC

Oscar Adriani University of Florence & INFN Firenze. Latest results from LHCf on very forward particle production at LHC. Latest results from the LHC CERN, July 12 th , 2012. Physics Motivations. Impact on High Energy Cosmic Ray Physics. The Cosmic Rays energy spectrum.

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Latest results from LHCf on very forward particle production at LHC

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  1. Oscar Adriani University of Florence & INFN Firenze Latest results from LHCf on very forward particle production at LHC Latest results from the LHC CERN, July 12th, 2012

  2. Physics Motivations Impact on High Energy Cosmic Ray Physics O. Adriani Latest results from LHCf Cern, July 12, 2012

  3. The Cosmic Rays energy spectrum 1 particle/m2/sec Direct Measurement by Balloon and Satellite 1 particle/m2/year Air shower technique 1 particle/km2/year 1 particle/km2/century

  4. Composition and energy of cosmic rays affect the generation of Extended Air Showers Precise understanding of high-energy cosmic ray should be achieved with the indirect measurement technique Comparison between the MC simulation of EAS and observation is necessary to infer the information on the primary CR from the measurement of the shower Largest systematic uncertainty of indirect measurement is caused by the finite understanding of the hadronic interaction of cosmic ray in atmosphere Indirect measurement of cosmic rays γ p Fe Altitude [km] Radius [km] O. Adriani Latest results from LHCf Cern, July 12, 2012

  5. Example I: the VHECR Energy spectrum Auger and Telescope Array are currently taking data Auger has the highest statistics. Two kinks: the ankle and the GZK cutoff Both Auger and TA spectra shows two kinks… BUT… The fluxes are significantly different! Energy scale problem?  Precise knowledge of the hadronic interaction mechanism at VHE is necessary O. Adriani Latest results from LHCf Cern, July 12, 2012

  6. Xmax Example II: Chemical Composition • BUT…. • The results depend on the precise knowledge of the hadronic interaction mechanism!!!!! • The Chemical composition can be inferred from the depth of the maximum of the shower (Xmax) Proton E=1019eV Gamma-ray Iron Auger Model uncertainty PROTON TA Shower depth [g/cm2] IRON 6 O. Adriani Latest results from LHCf Cern, July 12, 2012

  7. Xmax Example II: Chemical Composition • BUT…. • The results depend on the precise knowledge of the hadronic interaction mechanism!!!!! • The Chemical composition can be inferred from the depth of the maximum of the shower (Xmax) Proton Both in the energy determination and Xmax prediction MC simulations are used, and are one of the greater sources of uncertainty. Experimental tests of hadron interaction models are necessary!  LHCf E=1019eV Gamma-ray Iron Auger Model uncertainty PROTON TA Shower depth [g/cm2] IRON 7 O. Adriani Latest results from LHCf Cern, July 12, 2012

  8. Why LHCf @ LHC? The experimental set-up

  9. The Cosmic Ray spectrum LHC Energy range is very interesting for Cosmic Ray Physics! 14TeV 0.9TeV 7TeV Direct Indirect O. Adriani Latest results from LHCf Cern, July 12, 2012

  10. Air Shower development • Total cross section • Large σrapid development • Small σ deep penetrating • Multiplicity (N) • Large N  rapid development large number of muons • Small N deep penetrating small number of muons • Inelasticity(k)/Secondary spectra • Large k, Softer spectra  rapid development • Smallk, harder spectra deep penetrating O. Adriani Latest results from LHCf Cern, July 12, 2012

  11. LHC experiments Whole pseudo-rapidity is covered by the different LHC experiments Key parameters for air shower developments • Total cross section↔ TOTEM, ATLAS, CMS • Multiplicity ↔ Central detectors • Inelasticity/Secondary spectra↔Forward calorimetersLHCf, ZDCs R. Orava, (2005) O. Adriani Latest results from LHCf Cern, July 12, 2012

  12. 140 m 140 m γ 8 cm 6 cm n γ π0 Arm#2 Detector 25mmx25mm+32mmx32mm 4 X-Y Silicon strip layers Arm#1 Detector 20mmx20mm+40mmx40mm 4 X-Y SciFitracking layers LHCf: location and detector layout Detector II Tungsten Scintillator Silicon mstrips Detector I Tungsten Scintillator Scintillatingfibers INTERACTION POINT IP1 (ATLAS) Front Counter Front Counter 44 X0, 1.6 lint Expected Performance Energy resolution < 5% for g ~30% for neutrons Position resolution ~ 100μm O. Adriani Latest results from LHCf Cern, July 12, 2012

  13. What LHCf can measure? Energy spectra and Transverse momentum distribution of photons, neutrons and p0 in the pseudorapidity region h > 8.4 Multiplicity@14TeV Energy Flux @14TeV simulated by DPMJET3 High energy flux !! Low multiplicity !! O. Adriani Latest results from LHCf Cern, July 12, 2012

  14. What LHCf can measure? Energy spectra and Transverse momentum distribution of photons, neutrons and p0 in the pseudorapidity region > 8.4 Multiplicity@14TeV Energy Flux @14TeV The experimental challenge: Very precisely measure the highest energy LHC photons (up to 7 TeV) with the smallest LHC detector (~few cm2) simulated by DPMJET3 High energy flux !! Low multiplicity !! O. Adriani Latest results from LHCf Cern, July 12, 2012

  15. LHCf main physics results “Measurement of zero degree single photon energy spectra for √s = 900 GeV proton-proton collisions at LHC“ Submitted to PLB CERN-PH-EP-2012-048 “Measurement of zero degree single photon energy spectra for √s = 7 TeV proton-proton collisions at LHC“ PLB 703 (2011) 128 “Measurement of forward neutral pion transverse momentum spectra for √s = 7TeV proton-proton collisions at LHC“ Submitted to PRD CERN-PH-EP-2012-145 O. Adriani Latest results from LHCf Cern, July 12, 2012

  16. Inclusive g spectrum at 900 GeV Data DPMJET 3.04 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145 QGSJET II-03 MC/Data Gray hatch : Systematic Errors O. Adriani Latest results from LHCf Cern, July 12, 2012

  17. Inclusive g spectrum at 7 TeV Gray hatch : Systematic Errors Magenta hatch: MC Statistical errors Data MC/Data O. Adriani Latest results from LHCf Cern, July 12, 2012

  18. Inclusive g spectrum at 7 TeV Gray hatch : Systematic Errors Magenta hatch: MC Statistical errors Data None of the Models agrees with the data! These measurement are important to improve the hadronic interaction models in the high energy region MC/Data O. Adriani Latest results from LHCf Cern, July 12, 2012

  19. Comparison between 900 GeV and 7 TeV spectra Coverage of the photon spectra in the plane Feynman-X vs PT small-η = Large tower big-η =Small tower O. Adriani Latest results from LHCf Cern, July 12, 2012

  20. Comparison between 900 GeV and 7 TeV spectra Coverage of the photon spectra in the plane Feynman-X vs PT 900GeVvs. 7TeVwith the same PT region small-η = Large tower 900 GeV Small+large tower big-η =Small tower O. Adriani Latest results from LHCf Cern, July 12, 2012

  21. Comparison between 900 GeV and 7 TeV spectra Coverage of the photon spectra in the plane Feynman-X vs PT XF spectra : 900GeV data vs. 7TeV data Preliminary 900GeVvs. 7TeVwith the same PT region Data 2010 at √s=900GeV (Normalized by the number of entries in XF > 0.1)Data 2010 at √s=7TeV (η>10.94) small-η = Large tower 900 GeV Small+large tower big-η =Small tower • Normalized by the number of entries in XF > 0.1 • No systematic error is considered in both collision energies. Good agreement of XF spectrum shape between 900 GeV and 7 TeV. weak dependence of <pT> on ECMS O. Adriani Latest results from LHCf Cern, July 12, 2012

  22. 7 TeVπ0 analysis Mass, energy and transverse momentum are reconstructed from the energies and impact positions of photon pairs measured by each calorimeter 1(E1) R 140m  2(E2) I.P.1 O. Adriani Latest results from LHCf Cern, July 12, 2012

  23. p0 Data vs MC: PT spectra for different rapidity bins O. Adriani Latest results from LHCf Cern, July 12, 2012

  24. p0 Data vs MC • dpmjet3.04 &pythia 8.145 show overall agreement with LHCf data for 9.2<y<9.6 and pT<0.25 GeV/c, while the expected p0 production rates by both models exceed the LHCf data as pT becomes large • sibyll 2.1 predicts harder pion spectra than data, but the expected p0yield is generally small • qgsjet II-03 predicts p0 spectra softer than LHCf data • epos 1.99 shows the best overall agreement with the LHCfdata. • behaves softer in the low pT region, pT< 0.4GeV/c in 9.0<y<9.4 and pT <0.3GeV/c in 9.4<y<9.6 • behaves harder in the large pT region. O. Adriani Latest results from LHCf Cern, July 12, 2012

  25. π0 analysis at √s=7 TeV Submitted to PRD (arXiv:1205.4578). pT spectra vsbest-fit function Average pT vs ylab <PT> for different y bins PLB 242 531 (1990) YBeam=6.5 for SPS YBeam=8.92 for7 TeV LHC ylab = ybeam - y • Systematic uncertainty of LHCf data is 5%. • Comparison with the UA7 data (√s=630GeV) and MC simulations (QGSJET, SIBYLL, EPOS). • Two experimental data mostly appear to lie along a common curve→ No evident dependence of <pT> on ECMS. • Smallest dependence on ECMS is found in EPOS and it is consistent with LHCf and UA7. • Large ECMS dependence is found in SIBYLL O. Adriani Latest results from LHCf Cern, July 12, 2012

  26. What’s next and … conclusions … O. Adriani Latest results from LHCf Cern, July 12, 2012

  27. LHCf Future PLANS: Ionrun and 14 TeV 2010 2011/2012 2013 Pb –remnant side 2014 p –remnant side 14TeV LHC shutdown 7TeV Jul 2013: p-Pb runs • Interest in Ion runs • Physics case study well motivated • We will reinstall one ARM on p-remnant side during p-Pb run (beginning of 2013) 2014: 14 TeVp-pruns • Necessary to complete the LHCf physics program • The highest Elab will be reached (1017eV), to go closer to the VHECR region Detector upgrade Re-install Re-install n LHCf I LHCf-HI LHCf II  O. Adriani Latest results from LHCf Cern, July 12, 2012

  28. Conclusions • LHCf represent a very interesting and useful link between accelerator physics and cosmic ray physics • The experiment has been carefully designed to precisely measure the highest energy LHC photons (up to 7 TeV), despite being the smallest LHC detector (few cm2) • Nice physics results have been performed both on g and p0 • LHCf results have shown to be very useful for the very high energy cosmic rays models developer to improve their codes • p/Pb run in 2013 and 14 TeV p/p run in 2014 are the next important steps O. Adriani Latest results from LHCf Cern, July 12, 2012

  29. Backup slides

  30. What LHCf can measure in the p+Pb run E, pT,  spectra of neutral particles • We are simulating protons with energy Ep= 3.5 TeV • Energy per nucleon for ion is • “Arm2” geometry considered on both sides of IP1 to study both p-remnant side and Pb-remnant side • No detector response introduced yet (only geometrical considerations and energy smearing) • Results are shown for DPMJET 3.0-5 and EPOS 1.99, 107events each “p-remnant side” “Pb-remnant side” 140 m 140 m p-beam Pb-beam O. Adriani Latest results from LHCf Cern, July 12, 2012

  31. Proton remnant side – Photonspectra O. Adriani Latest results from LHCf Cern, July 12, 2012

  32. Proton remnant side - Neutronspectra O. Adriani Latest results from LHCf Cern, July 12, 2012

  33. Lead-remnant side – multiplicityPlease remind that EPOS does not consider Fermi motion and Nuclear Fragmentation Small tower Big tower  n O. Adriani Latest results from LHCf Cern, July 12, 2012

  34. What LHCf can measure in the p+Pb run (2)Study of the Nuclear Modification Factor Nuclear Modification Factor measured at RHIC (production of p0): strong suppression for small pt at <>=4. LHCf can extend the measurement at higher energy and for >8.4 Very important for CR Physics Phys. Rev. Lett. 97 (2006) 152302 O. Adriani Latest results from LHCf Cern, July 12, 2012

  35. Muon excess at Pierre Auger Obs. • Auger hybrid analysis • event-by-event MC selection to fit FD data (top-left) • comparison with SD data vs MC (top-right) • muon excess in data even for Fe primary MC • EPOS predicts more muon due to larger baryon production • => importance of baryon measurement Pierre Auger Collaboration, ICRC 2011 (arXiv:1107.4804) Pierog and Werner, PRL 101 (2008) 171101 O. Adriani Latest results from LHCf Cern, July 12, 2012

  36. Neutron at LHCf phase-space By Tanguy Pierog, Modelists waiting for LHCf!! O. Adriani Latest results from LHCf Cern, July 12, 2012

  37. Arm1 vs Arm2 comparison O. Adriani Latest results from LHCf Cern, July 12, 2012

  38. π0 spectrum and air showers Longitudinal AS development DPMJET3 original Artificial modification • Artificial modification of meson spectra (in agreement with differences between models) • D<Xmax(p-Fe)> ~ 100 g/cm2 • Effect to air shower ~ 30 g/cm2 <Xmax>=718 g/cm2 <Xmax>=689 g/cm2 Vertical Depth (g/cm2) π0 spectrum at Elab = 1017eV AUGER, ICRC 2011 O. Adriani Latest results from LHCf Cern, July 12, 2012

  39. LHCf operations @900 GeV & 7 TeV • With Stable Beam at 900 GeV Dec 6th – Dec 15th 2009 • With Stable Beam at 900 GeVMay 2nd – May 27th 2010 • With Stable Beam at 7 TeVMarch 30th - July 19th 2010 • We took data with and without 100 μrad crossing angle for different vertical detector positions O. Adriani Latest results from LHCf Cern, July 12, 2012

  40. p0 reconstruction An example of p0 events measured energy spectrum @ Arm2 25mm 32mm preliminary Silicon strip-X view 1(E1) Reconstructed mass @ Arm2 R 140m  2(E2) I.P.1 • p0’s are the main source of electromagnetic secondaries in high energy collisions. • The mass peak is very useful to confirm the detector performances and to estimate the systematic error of energy scale. O. Adriani Latest results from LHCf Cern, July 12, 2012

  41. h Mass Arm2 detector, all runs with zero crossing angle True hMass: 547.9 MeV MC Reconstructed hMass peak: 548.5 ± 1.0 MeV Data Reconstructed hMass peak: 562.2 ± 1.8 MeV (2.6% shift) O. Adriani Latest results from LHCf Cern, July 12, 2012

  42. π0 analysis at √s=7TeV Submitted to PRD (arXiv:1205.4578). Type-I Type-II • Small angle • large BG • Low-stat., but can cover • High-E • Large-PT • Large angle • Simple • Clean • High-stat. Type-ILHCf-Arm1 Type-IILHCf-Arm1 LHCf-Arm1Data 2010 Preliminary Type-II at large tower BG Type-II at small tower Signal O. Adriani Latest results from LHCf Cern, July 12, 2012

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