Calibration of Hadron Interaction Models for High Energy Cosmic Ray Physics at the LHC

1. LHCf: Calibration of hadron interaction models for high energy cosmic-ray physics at the LHC energy T.Mase for the LHCf collaboration Nagoya University, Solar-Terrestrial Environment Laboratory

2. Physics motivation of LHCf • To reduce the uncertainty of hadron interaction models by using LHC accelerator • LHCf measures neutral particles emitted in very forward (including zero degree) in the LHC collisions • To discriminate existing interaction models and provide crucial data for future models Tours2009 T.Mase

3. The LHCf collaboration Y.Itow, K.Kawade, T.Mase, K.Masuda, Y.Matsubara, G.Mitsuka, T.Sako, K.TakiSolar-Terrestrial Environment Laboratory, Nagoya University, Japan K.YoshidaShibaura Institute of Technology, Japan K.Kasahara, M.Nakai, S.Torii Waseda University, Japan T.TamuraKanagawa University, Japan Y.MurakiKonan University Y.ShimizuICRC, University of Tokyo, Japan M.HaguenauerEcole Polytechnique, France W.C.TurnerLBNL, Berkeley, USA O.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, H.Menjo, P.Papini, S.Ricciarini, G.Castellini, A. Viciani INFN, Univ. di Firenze, Italy A.TricomiINFN, Univ. di Catania, Italy J.Velasco, A.FausIFIC, Centro Mixto CSIC-UVEG, Spain D.Macina, A-L.PerrotCERN, Switzerland Tours2009 T.Mase

4. Air shower and hadron interaction model • Primary cosmic rays interact with the atmospheric molecules • The air shower is developed by hadron interactions and electromagnetic cascades • The air shower experiments measure the secondary particles on the ground • To know the primary information, we must reconstruct the shower Simulation Tours2009 T.Mase

5. Energy spectrum of cosmic rays absolute energy scale doesn't agree uncertainty of hadron interaction model Confirmation of the various models using the LHC is important key for the cosmic ray physics. GZK cutoff; Propagation limit due to CMB Tours2009 T.Mase

6. Experimental Overview TAN ATLAS(IP1) LHCf detector 96mm neutral particle absober LHCf Detector 140m away from the interaction point • LHCf is one of six experiments of LHC • 7TeV+7TeV corresponds 1.0x1017eV(Lab. system) • Detectors are installed at the 140m away from theInteraction Point 1 • In the TAN, beam pipe is separated into two pipes, 96mm gap between these pipes • Installed both sides of IP1, named Arm1 and Arm2 • LHCf covers pseudorapidity h > 8.4 I.P. Tours2009 T.Mase

7. Schematic view of LHCf detectors Arm#1 Detector 20mmx20mm+40mmx40mm 4 XY SciFi+MAPMT Arm#2 Detector 25mmx25mm+32mmx32mm 4 XY Silicon strip detectors • Sampling & imaging calorimeters both sides of IP1 • Two small tower calorimeters in both detectors (Tungsten 44r.l., 1.7λ, 16 plastic scintillator sampling layers, 4 position sensitive layers) 25mm 32mm 40mm 20mm Tours2009 T.Mase

8. Double arm detectors Arm#1 Detector Arm#2 Detector 280mm 92mm 90mm 280mm Tours2009 T.Mase

9. Discriminate the hadron interaction models Gamma Spectrum • LHCf measures the neutral particles emitted in the very forward region of LHC • The main targets are gamma-ray, neutron and p0 • The difference between models is evaluated by shape of the spectrum p0 Spectrum Neutron Spectrum Tours2009 T.Mase

10. p0 analysis • p0s are reconstructed from 2g • Peak of the mass is seen • p0 (generated by DPMJET3) mass is reconstructed by Full MC • Other interaction models generated by rather simple MC • c2 test shows that LHCf can discriminate the models Peak=134MeV σ=4.9MeV DOF=17 Tours2009 T.Mase

11. Schedule of LHCf Beam Energy (TeV) • LHCf will take data for all energies Lab. Energy (eV) operation upgrade operation 5-7 1.0x1017 7 ? 4-5 5.1x1016 5 3.5 heavy ion 1.8x1016 3 1.1 4.1x1014 0.45 0.45 2009 2010 2011- Tours2009 T.Mase

12. Summary • LHCf will measure the energy and transverse momentum of neutral particles emitted in the forward region of the LHC • The physics goal is to provide the data for calibration of the hadron interaction model of cosmic ray at LHC energy • LHC will start in this year and increase energy up to 7TeV and LHCf will take data for each energy • LHCf can discriminate and improve the hadron interaction model • Zero-degree data of gamma-rays, neutrons and p0s • The hadron interaction models can be well discreminated by using energy spectra Tours2009 T.Mase

13. Fin.

14. Cosmic ray measurement Xmaxsuggest heavy primary interpretation strongly depends on the hadron interaction model Confirmation of the various models using the LHC is important key for the cosmic ray physics. Anisotropy suggest light primary (if accept AGN correlation) Tours2009 T.Mase

15. Gamma Spectrum Discrimination of hadron interaction model • LHCf measure the neutral particle emitted in the very forward region of LHC • Expected spectrum of gamma-ray is different by hadron interaction models • The difference between models is evaluated by shape of the spectrum Nidata(b)=N(bEg) is i-th bin of the energy spectrum of reference (QGSJET-II) Nimodel=N(Eg) is i-th bin of energy spectrum of test (QGSJET, DPMJET3 and SIBYLL) a is a normalization factor b is a scale factor sidata, simodel are statistical errors of the i-th bin DOF=67 Tours2009 T.Mase