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Status of LHCf

Status of LHCf. Alessia Tricomi University of catania & INFN catania on behalf of the LHCf collaboration. Forward photon energy spectrum at √s = 7 TeV p-P collisions Prospects for new analyses Detector upgrade. CSN1 Napoli, July 5, 2011. Physics motivations.

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Status of LHCf

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  1. Status of LHCf Alessia Tricomi University of catania & INFN catania on behalf of the LHCf collaboration • Forward photon energy spectrum at √s = 7 TeV p-P collisions • Prospects for new analyses • Detector upgrade CSN1 Napoli, July 5, 2011

  2. Physics motivations IMPACT on HECR PHYSICS Alessia Tricomi CNS1, Napoli, July 5, 2011

  3. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  4. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  5. LHcf @ LHC Alessia Tricomi CNS1, Napoli, July 5, 2011

  6. 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 cover |h|>8 Front Counters: thin scintillators with 8x8cm2acceptance installed in front of each main detector Alessia Tricomi CNS1, Napoli, July 5, 2011

  7. 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 & p0, 30% for neutrons Position resolution < 200μm (Arm#1), 40μm (Arm#2) Alessia Tricomi CNS1, Napoli, July 5, 2011

  8. η 8.5 ∞ How lhcf can contribute? LHC gives us the unique opportunity to measure hadronic interactions at 1017eV Cosmic ray spectrum SPS Forward region is very effective on air shower development. Tevatron LHC High energy flux !! Low multiplicity !! AUGER 7TeV+7TeV →Elab= 1017eV 3.5TeV+3.5TeV →Elab= 2.6x1016eV 450GeV+450GeV →Elab= 2x1014eV DPMJET3 Status of LHCf Alessia Tricomi CNS1, Napoli, July 5, 2011

  9. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  10. Inclusive photon spectrum analysis Lhcf data taking PAPER accepted for publication on 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  11. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  12. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  13. 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) Alessia Tricomi CNS1, Napoli, July 5, 2011 Shower leakage-in Light collection nonuniformity Shower leakage-out

  14. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  15. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  16. 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. Alessia Tricomi CNS1, Napoli, July 5, 2011

  17. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  18. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  19. Analysis 6. – combination of arm1 and arm2 spectra Gray hatch : Systematic Errors Error bars : statistical Error Alessia Tricomi CNS1, Napoli, July 5, 2011

  20. 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% Alessia Tricomi CNS1, Napoli, July 5, 2011

  21. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  22. results Alessia Tricomi CNS1, Napoli, July 5, 2011

  23. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  24. Impact on HECR Physics Understanding the impact of our measurements Alessia Tricomi CNS1, Napoli, July 5, 2011

  25. Understanding the impact of our measurements on HECR • The most tricky part • We have started a cooperation with several theoreticians • First meeting in Florence in mid of May • Authors of Corsika – EPOS • Mini-workshop Catania July 6th-8th • P. Lipari, R. Ulrich, AUGER • In touch also with Pythia experts • CERN Workshop to be organized together with M. Mangano Alessia Tricomi CNS1, Napoli, July 5, 2011

  26. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  27. What’s next Detector upgrade, analysis, ion runs Alessia Tricomi CNS1, Napoli, July 5, 2011

  28. EJ260 8 Silicon Layers 6 6 12 12 18 26 34 42 X0 Future activities (I) 2011-2012 • Replaceplasticscintillators with Rad Hard GSO (prepared by Japan side) in Florence Clean Rooms • Produce 2 new siliconmodules to replacepartlydefectiveones + 2 spares • Modify the siliconlayers positions to improvesilicon-onlyenergyresoution • Test beamat SPS to calibrate Arm1&Arm2 • Improve the dynamicrange of silicon detectors (limited by Pace3 saturationeffect)? Alessia Tricomi CNS1, Napoli, July 5, 2011

  29. Future activities (II) • 2012 • Big interest in Ion runs (better if light ions) • LHC Ion run and/or RHIC • Discussion on going with LHCC, LHC machine, ATLAS about reinstallation during Ion run (end of 2012?) • Discussion also about the possibility to install and take data at RHIC (geometrical feasibility good) Alessia Tricomi CNS1, Napoli, July 5, 2011

  30. Future activities (III) • New analyses already started • Priority list will be discussed during this week • p0 measurement • Hadron spectra • pT spectra • h, k0, L ? • …. Alessia Tricomi CNS1, Napoli, July 5, 2011

  31. NEXT TO Future activities • 2014-2015 • Re-install Arm1&Arm2 at LHC when the energywill be raised to 13/14 TeV • Necessity to mantain the Cerninfrastructures: • Control room • Electronics pool material • Safetyinfrastructures • Racks in underground areas • Team account • Etc. etc. etc. Alessia Tricomi CNS1, Napoli, July 5, 2011

  32. conclusions • LHCf Inclusive photon analysis has been completed • Many detailed systematic checks • 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) • 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 analyses are in progress (hadrons, PT distributions, different h coverage…) • LHCf was removed from the tunnel on July 20, 2010 • We are upgrading the detectors to improve their radiation hardness (GSO scintillators and rearrange silicon layers) • Discussions are under way to come back in the TAN for the possible p-Pb run in 2012 (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!!!! Alessia Tricomi CNS1, Napoli, July 5, 2011

  33. LHCfringraziaparticolarmenteilPresidenteuscente per l’affetto, l’incoraggiamento e ilsostegnoche ha sempremostrato al piu’ piccolo deisuoiesperimenti Chesperiamo di aver ripagato con unapiccolasoddisfazione Alessia Tricomi CNS1, Napoli, July 5, 2011

  34. Backup slides Alessia Tricomi CNS1, Napoli, July 5, 2011

  35. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  36. Key measurements E0 EM shower E leading baryon Forward spectra (Multiplicity) Cross section Elasticity / inelasticity Alessia Tricomi CNS1, Napoli, July 5, 2011

  37. 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 !!! Alessia Tricomi CNS1, Napoli, July 5, 2011

  38. Model uncertainty at LHC energy Very similar!? Forward concentration of x>0.1 π0 π0 energy at √s = 7TeV Alessia Tricomi CNS1, Napoli, July 5, 2011

  39. 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. Alessia Tricomi CNS1, Napoli, July 5, 2011

  40. EJ260 R&D for the detector upgrade Scintillating Fibers ⇒GSO bars Plastic scintillators (EJ260) ⇒ GSO scintillators Radiation damage measured by Ion beams MIP peak Alessia Tricomi CNS1, Napoli, July 5, 2011

  41. 8 Silicon Layers 6 6 12 12 18 26 34 42 X0 New silicon layers arrangement Alessia Tricomi CNS1, Napoli, July 5, 2011

  42. Front Counter • Fixed scintillation counter • L=CxRFC; conversion coefficient calibrated during VdM scans Alessia Tricomi CNS1, Napoli, July 5, 2011

  43. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  44. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  45. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  46. Beam center measurement Beam center LHCf vs BPMSW LHCf online hit-map monitor Effect of 1mm shift in the final spectrum Alessia Tricomi CNS1, Napoli, July 5, 2011

  47. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  48. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  49. 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 Alessia Tricomi CNS1, Napoli, July 5, 2011

  50. 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. Alessia Tricomi CNS1, Napoli, July 5, 2011

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