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Status of LHCf

Status of LHCf. Oscar Adriani University of Florence & INFN Sez . Di Firenze on behalf of the LHCf collaboration. PLHC2011 Perugia, June 6, 2011. Contents. Physics motivations Ultra High Energy Cosmic Rays open issues How LHCf can contribute in this field

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Status of LHCf

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  1. Status of LHCf Oscar Adriani University of Florence & INFN Sez. Di Firenze on behalf of the LHCf collaboration PLHC2011 Perugia, June 6, 2011

  2. Contents • Physics motivations • Ultra High Energy Cosmic Rays open issues • How LHCf can contribute in this field • Overview of the LHCf experiment • Forward photon energy spectrum at √s = 7eV proton-proton collisions • Summary and outlooks Oscar Adriani PLHC2011, Perugia, June 6, 2011

  3. The LHCf collaboration K.Fukatsu, T.Iso, Y.Itow, K.Kawade, T.Mase, K.Masuda, Y.Matsubara, G.Mitsuka, Y.Muraki, T.Sako, K.Suzuki, K.TakiSolar-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.ToriiWaseda University, Japan T.TamuraKanagawa University, Japan O.Adriani, L.Bonechi, M.Bongi, R.D’Alessandro, M.Grandi, P.Papini, S.Ricciarini, G.CastelliniINFN, Univ. di Firenze, Italy K.Noda, A.TricomiINFN, Univ. di Catania, Italy M.HaguenauerEcolePolytechnique, France W.C.TurnerLBNL, Berkeley, USA A-L.Perrot CERN, Switzerland Oscar Adriani PLHC2011, Perugia, June 6, 2011

  4. Physics motivations Oscar Adriani PLHC2011, Perugia, June 6, 2011

  5. UHECR Observations (10 years ago and now) • Debate in AGASA, HiRes results in 10 years ago • Now Auger, HiRes (final), TA indicate cutoff • Absolute values differ between experiments and between methods Oscar Adriani PLHC2011, Perugia, June 6, 2011

  6. Estimate of Particle Type (Xmax) 0g/cm2 Xmax Auger 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 TA HiRes Proton and nuclear showers of same total energy • Xmax gives information of the primary particle • Results are different between experiments • Interpretation relies on the MC prediction and has quite strong model dependence Oscar Adriani PLHC2011, Perugia, June 6, 2011

  7. The role of LHcf Oscar Adriani PLHC2011, Perugia, June 6, 2011

  8. Total cross section↔ TOTEM, ATLAS(ALFA) Multiplicity ↔ Central detectors Inelasticity/Secondary spectra↔Forward calorimetersLHCf, ZDCs How lhc can contribute? LHC gives us the unique opportunity to measure hadronic interactions at 1017eV 7TeV+7TeV →Elab= 1017eV 3.5TeV+3.5TeV →Elab= 2.6x1016eV 450GeV+450GeV →Elab= 2x1014eV Cosmic ray spectrum Key parameters for air shower developments SPS Tevatron LHC AUGER Oscar Adriani PLHC2011, Perugia, June 6, 2011

  9. η 8.5 ∞ What LHCfcan measure? Front view of calorimeters @ 100μrad crossing angle • Energy spectra and Transverse momentum • distribution of • Gamma-rays (E>100GeV,dE/E<5%) • Neutral Hadrons (E>a few 100 GeV, dE/E~30%) • π0 (E>600GeV, dE/E<3%) • in the pseudo-rapidity range h>8.4 Projected edge of beam pipe Forward region is very effective on air shower development. Multiplicity@14TeV Energy Flux @14TeV High energy flux !! Low multiplicity !! Oscar Adriani PLHC2011, Perugia, June 6, 2011 DPMJET3

  10. π0 spectrum and air shower QGSJET II original Artificial modification X=E/E0 Ignoring X>0.1 meson π0 spectrum at Elab = 1019eV Longitudinal AS development 30g/cm2 • Artificial modification of meson spectra (in agreement with differences between models) and its effect to air shower • Importance of E/E0>0.1 mesons Oscar Adriani PLHC2011, Perugia, June 6, 2011

  11. Protons Charged particles Neutral particles Beam pipe LHCf Experimental Set-up Detectors installed in the TAN region, 140 m away from ATLAS Interaction Point (IP1) • Herethe beam pipe splits in 2 separate tubes. • Chargedparticle are sweptawaybymagnets • We will cover |h|>8 Front Counters: thin scintillators with 8x8cm2acceptance installed in front of each main detector Oscar Adriani PLHC2011, Perugia, June 6, 2011

  12. 90mm Arm#2 ARM1 & ARM2 detectors 4 pairs of scintillating fiber layers for tracking purpose (6, 10, 32, 38 r.l.) • ARM1 • 2 towers 24 cm long stacked vertically with 5 mm gap • Lower: 2 cm x 2 cm area • Upper: 4 cm x 4 cm area Impact point (h) 4 pairs of silicon microstriplayers (6, 12, 30, 42 r.l.) for tracking purpose (X and Y directions) Absorber 22 tungsten layers 7– 14 mm thick (2-4 r.l.) (W: X0 = 3.5mm, RM = 9mm) 290mm ARM2 2 towers 24 cm long stacked on theiredges and offset from oneanother Lower: 2.5 cm x 2.5 cm Upper: 3.2 cm x 3.2 cm Arm#1 Energy 16 scintillator layers (3 mm thick) Trigger and energy profile measurements Expected Performance Energy resolution (> 100GeV) < 5% for g, 30% for neutrons Position resolution < 200μm (Arm#1), 40μm (Arm#2) Oscar Adriani PLHC2011, Perugia, June 6, 2011

  13. ATLAS & LHCf Oscar Adriani PLHC2011, Perugia, June 6, 2011

  14. 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 • Pi0’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.

  15. Inclusive photon spectrum analysis Lhcf data taking PAPER submitted to PLB “Measurement of zero degree single photon energy spectra for √s = 7 TeV proton-proton collisions at LHC“ arXiv:1104.5294 CERN-PH-EP-2011-061, Oscar Adriani PLHC2011, Perugia, June 6, 2011

  16. 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 Oscar Adriani PLHC2011, Perugia, June 6, 2011

  17. Data Set for inclusive photon spectrum analysis • Data • Date : 15 May 2010 17:45-21:23 (Fill Number : 1104) except runs during the luminosity scan. • Luminosity : (6.5-6.3)x1028cm-2s-1, • DAQ Live Time : 85.7% for Arm1, 67.0% for Arm2 • Integrated Luminosity : 0.68 nb-1for Arm1, 0.53nb-1 for Arm2 • Number of triggers : 2,916,496 events for Arm13,072,691 events for Arm2 • Detectors in nominal positions and Normal Gain • Monte Carlo • QGSJET II-03, DPMJET 3.04, SYBILL 2.1, EPOS 1.99 and PYTHIA8.145: about 107pp inelastic collisions each Oscar Adriani PLHC2011, Perugia, June 6, 2011

  18. Analysis procedure Oscar Adriani PLHC2011, Perugia, June 6, 2011

  19. Analysis for the photon spectra • Analysis Procedure • Energy Reconstruction from total energy deposition in a tower (corrections for shower leakage, light yield etc.) • Particle Identification by analysis of the longitudinal shower development • Remove multi-particle events by looking at transverse energy deposit • Two Pseudo-rapidity regions selections, η>10.94 and8.81<η<8.9 • Combine spectra between the two detectors • Compare data with the expectations from the models Oscar Adriani PLHC2011, Perugia, June 6, 2011

  20. Analysis 1. - Energy reconstruction • Energy reconstruction: Ephoton = f(Σ(dEi)) (i=2,3,…,13) ( dEi = AQi determined at SPS. f() determined by MC. E : EM equivalent energy) • Impact position from lateral distribution • Position dependent corrections • Light collection non-uniformity • Shower leakage-out • Shower leakage-in (in case of two towers event) Shower leakage-in Light collection nonuniformity Shower leakage-out

  21. Analysis 1. - Energy reconstruction Arm2 Measurement 1(E1) Arm2 MC R 140m  2(E2) I.P.1 M = θ√(E1xE2) • Energy scale can be checked by π0 identification from two tower events. • Mass shift observed both in Arm1 (+7.8%) and Arm2 (+3.7%) • No energy scaling applied, but shifts assigned in the systematic errorin energy Oscar Adriani PLHC2011, Perugia, June 6, 2011

  22. Analysis 2. - Particle Identification PID criteria based on transition curve 500 GeV <EREC<1 TeV MC/Data comparison done in many energy bins • QGSJET2-gamma and -hadron are normalized to data(/collision) independently • LPM effects are switched on Oscar Adriani PLHC2011, Perugia, June 6, 2011

  23. Analysis 3. -Multi-hit identification Double hit detection efficiency Small tower Large tower Arm1 Single hit detection efficiency Arm2 • Reject events with multi-peaks • Identify multi-peaks in one tower by position sensitive layers. • Select only the single peak events for spectra. Oscar Adriani PLHC2011, Perugia, June 6, 2011

  24. Analysis 4. - Acceptance Cut We define in each tower a region common both to Arm1 and Arm2, to compare the Arm1 and Arm2 reconstructed spectra. Our final results will be two spectra, one for each acceptance region, obtained by properly weighting the Arm1 and Arm2 spectra R1 = 5mm R2-1 = 35mm R2-2 = 42mm q= 20o For Small Tower h> 10.94 For Large Tower 8.81 < h< 8.99 Oscar Adriani PLHC2011, Perugia, June 6, 2011

  25. Analysis 5. – comparison of arm1 and arm2 spectra Deviation in small tower: still unclear, but within systematic errors - Multi-hit rejection and PID correction applied - Energy scale systematic not considered due to strong correlation between Arm1 and Arm2 Oscar Adriani PLHC2011, Perugia, June 6, 2011

  26. Analysis 6. – combination of arm1 and arm2 spectra Gray hatch : Systematic Errors Error bars : statistical Error Oscar Adriani PLHC2011, Perugia, June 6, 2011

  27. Backgrounds Beam-Gas backgrounds Secondary-beam pipe backgrounds • Pileup of collisions in one beam crossing • Low Luminosity fill, L=6x1028cm-2s-1 7% pileup at collisions, 0.2% at the detectors. • Collisions between secondary's and beam pipes • Very low energy particles reach the detector (few % at 100GeV) • Collisions between beams and residual gas • Estimated from data with non-crossing bunches. <0.1%

  28. Systematic Uncertainties Estimated for Arm1 and Arm2 by same methods but independently Estimated by Arm2, and apply it to the both Arm Please have a look to the paper for detailed explanations! Uncorrelated uncertainties between ARM1 and ARM2- Energy scale (except p0error)- Beam center position- PID- Multi-hit selection Correlated uncertainty- Energy scale (p0error)- Luminosity error Oscar Adriani PLHC2011, Perugia, June 6, 2011

  29. results Oscar Adriani PLHC2011, Perugia, June 6, 2011

  30. Comparison between Models DPMJET 3.04 SIBYLL 2.1 EPOS 1.99 PYTHIA 8.145 QGSJET II-03 Magenta hatch: MC Statistical errors Gray hatch : Systematic Errors Oscar Adriani PLHC2011, Perugia, June 6, 2011

  31. conclusions • LHCf Inclusive photon analysis has been completed • Many detailed systematic checks were necessary! • First comparison of various hadronic interaction models with experimental data in the most challenging phase space region (8.81 < h < 8.99, h > 10.94) • None of the models perfectly agree with data • Large discrepancy especially in the high energy region with all models. • Implications on UHECR Physics under study in strict connection with relevant theoreticians and model developers • Other analysis are in progress (hadrons, PT distributions, different h coverage etc.) • LHCf was removed from the tunnel on July 20, 2010 • We are upgrading the detectors to improve their radiation hardness (GSO scintillators) • Discussions are under way to come back in the TAN for the possible p-Pb run in 2013 (LHCC, Alice, LHC, Atlas etc.) or at RHIC for lower energy p-ions runs • We will anyway come back in LHC for the 14 TeV run with upgraded detector!!!!

  32. Backup slides Oscar Adriani PLHC2011, Perugia, June 6, 2011

  33. Key measurements E0 EM shower E leading baryon Forward spectra (Multiplicity) Cross section Elasticity / inelasticity

  34. Key parameters for the development of the showers Inelasticity/Secondary particles Multiplicity Total cross section Predictions of the hadronic interaction models most commonly used in the UHECR simulation Big discrepancy in the high energy region !!! Oscar Adriani PLHC2011, Perugia, June 6, 2011

  35. Model uncertainty at LHC energy Very similar!? Forward concentration of x>0.1 π0 π0 energy at √s = 7TeV Oscar Adriani PLHC2011, Perugia, June 6, 2011

  36. Front Counter • Fixed scintillation counter • L=CxRFC; conversion coefficient calibrated during VdM scans Oscar Adriani PLHC2011, Perugia, June 6, 2011

  37. η η θ [μrad] 8.5 8.7 310 ∞ ∞ 0 Calorimeters viewed from IP 100urad crossing angle 0 crossing angle Projected edge of beam pipe • Geometrical acceptance of Arm1 and Arm2 • Crossing angle operation enhances the acceptance Oscar Adriani PLHC2011, Perugia, June 6, 2011

  38. Luminosity Estimation VDM scan Beam sizes sx and sy measured directly by LHCf BCNWG paper https://lpc-afs.web.cern.ch/lpc-afs/tmp/note1_v4_lines.pdf Luminosity for the analysis is calculated from Front Counter rates: The conversion factor CF is estimated from luminosity measured during Van der Meer scan Oscar Adriani PLHC2011, Perugia, June 6, 2011

  39. Estimation of Pile up When the circulated bunch is 1x1, the probability of N collisions per Xing is The ratio of the pile up event is The maximum luminosity per bunch during runs used for the analysis is 2.3x1028cm-2s-1 So the probability of pile up is estimated to be 7.2% with σ of 71.5mb Taking into account the calorimeter acceptance (~0.03) only 0.2% of events have multi-hit due to pile-up. It does not affect our results Oscar Adriani PLHC2011, Perugia, June 6, 2011

  40. Beam center measurement Beam center LHCf vs BPMSW LHCf online hit-map monitor Oscar Adriani PLHC2011, Perugia, June 6, 2011 Effect of 1mm shift in the final spectrum

  41. Uncertainty in Step.2 (Small tower, single & gamma-like) Original method Template fitting A ε/P from two methods Artificial modification in peak position(<0.7 r.l.) and width (<20%) (ε/P)B/(ε/P)A Template fitting B • Imperfection in L90% distribution Oscar Adriani PLHC2011, Perugia, June 6, 2011

  42. Uncertainty in Step.3 Effect of Δεmulti to single photon spectra Single / (single+multi), Arm1 vs Arm2 • Fraction of multi-hit and Δεmulti, data-MC • Effect of multi-hit ‘cut’ : difference between Arm1 and Arm2

  43. Spectral deformation TRUE/MEASURED TRUE MEASURED True: photon energy spectrum at the entrance of calorimeter • Suppression due to multi-hit cut at medium energy • Overestimate due to multi-hit detection inefficiency at high energy (mis-identify multi photons as single) • No correction applied, but same bias included in MC to be compared Oscar Adriani PLHC2011, Perugia, June 6, 2011

  44. Systematic error from Energy scale • Two components:- Relatively well known: Detector response, SPS => 3.5%- Unknown: p0 mass => 7.8%, 3.8% for Arm1 and Arm2. • Please note: • - 3.5% is symmetric around measured energy • - 7.8% (3.8%) are asymmetric, because of the p0 mass shift • - No ‘hand made’ correction is applied up to now for safety • Total uncertainty is -9.8% / +1.8% for Arm1 -6.6% / +2.2% for Arm2 Systematic Uncertainty on Spectra is estimated from difference between normal spectra and energy shifted spectra. Oscar Adriani PLHC2011, Perugia, June 6, 2011

  45. p0Mass Arm1 Data • Disagreement in the peak position • No ‘hand made correction’ is applied for safety • Main source of systematic error  see later Peak at 145.8 ± 0.1MeV Many systematic checks have been done to understand the energy scale difference 7.8 % shift Arm2 Data Arm2 MC (QGSJET2) Peak at 135.0 ± 0.2 MeV Peak at 140.0 ± 0.1 MeV 3.8 % shift Oscar Adriani PLHC2011, Perugia, June 6, 2011

  46. p0 mass vsp0energy Arm2 Data No strong energy dependence of reconstructed mass Oscar Adriani PLHC2011, Perugia, June 6, 2011

  47. 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) Oscar Adriani PLHC2011, Perugia, June 6, 2011

  48. Effect of mass shift ±3.5% Gaussian probability ±7.8% flat probability Quadratic sum of two errors is given as energy error (to allow both 135MeV and observed mass peak) 135MeV 145.8MeV (Arm1 observed) • Energy rescaling NOT applied but included in energy error • Minv = θ √(E1 x E2) • (ΔE/E)calib = 3.5% • Δθ/θ = 1% • (ΔE/E)leak-in= 2% => ΔM/M = 4.2% ; not sufficient for Arm1 (+7.8%) Oscar Adriani PLHC2011, Perugia, June 6, 2011

  49. π0 mass shift in study • Reanalysis of SPS calibration data in 2007 and 2010 (post LHC) <200GeV • Reevaluation of systematic errors • Reevaluation of EM shower using different MC codes (EPICS, FLUKA, GEANT4) • Cable attenuation recalibration(1-2% improve expected) • Re-check all 1-2% effects… Oscar Adriani PLHC2011, Perugia, June 6, 2011

  50. Summary of systematic errors Oscar Adriani PLHC2011, Perugia, June 6, 2011

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