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LHCf status and results

LHCf status and results. Oscar Adriani on behalf of the LHCf collaboration. CERN, 23 MARCH 2011. HECR Open Issues. AGASA x 0.9 AUGER x 1.3. M Nagano New Journal of Physics 11 (2009) 065012. Difference in the energy scale between different experiments???.

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LHCf status and results

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  1. LHCf status and results Oscar Adriani on behalf of the LHCf collaboration CERN, 23 MARCH 2011

  2. HECR Open Issues AGASA x 0.9 AUGER x 1.3 M Nagano New Journal of Physics 11 (2009) 065012 Difference in the energy scale between different experiments??? Different hadronic interaction models give different answers about the composition of HECR The depth of the maximum of the shower Xmax depends on energy and type of the primary particle Oscar Adriani LHCC Meeting, CERN 23 March 2011

  3. 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 LHCC Meeting, CERN 23 March 2011

  4. 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 Oscar Adriani LHCC Meeting, CERN 23 March 2011

  5. Inclusive photon spectrum analysis Lhcf data taking Oscar Adriani LHCC Meeting, CERN 23 March 2011

  6. 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 • We took data with and without 100 μrad crossing angle for different vertical detector positions Oscar Adriani LHCC Meeting, CERN 23 March 2011

  7. 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 LHCC Meeting, CERN 23 March 2011

  8. 1 TeVp0 candidate event Longitudinal profile A p0candidate event 599GeV gamma-ray and 419GeV gamma-ray in 25mm and 32mm tower respectively. Transverse profile Oscar Adriani LHCC Meeting, CERN 23 March 2011

  9. 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 LHCC Meeting, CERN 23 March 2011

  10. Particle identification Oscar Adriani LHCC Meeting, CERN 23 March 2011

  11. 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 LHCC Meeting, CERN 23 March 2011

  12. PID correction Hatched : dataRed : true-gammaBlue : true-hadronGreen : Red+Blue Bin by bin (energy) correction applied to take into account shape disagreement between Data/MC (see systematic error section) Efficiency and purity for gamma-ray estimated from L90% fitting with MC template (QGSJET2). Oscar Adriani LHCC Meeting, CERN 23 March 2011

  13. Energy Scale Issue Oscar Adriani LHCC Meeting, CERN 23 March 2011

  14. 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 LHCC Meeting, CERN 23 March 2011

  15. p0 mass vsp0energy Arm2 Data No strong energy dependence of reconstructed mass Oscar Adriani LHCC Meeting, CERN 23 March 2011

  16. 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 LHCC Meeting, CERN 23 March 2011

  17. Multi hit rejection Oscar Adriani LHCC Meeting, CERN 23 March 2011

  18. Multi-Hit rejection In order to extract inclusive single gamma spectra, rejection of multi-hit events is mandatory especially at high energy (> 2.5 TeV) Oscar Adriani LHCC Meeting, CERN 23 March 2011

  19. Multi-Hit rejection Multi-hit events are identified thanks to position sensitive layers in ARM1 (SciFi) and Arm2 (Si-mstrip) Oscar Adriani LHCC Meeting, CERN 23 March 2011

  20. Multi-Hit rejection Single gamma detection efficiency for various MC models Multi gamma detection efficiency for various MC models Please have a look to systematic error section! Oscar Adriani LHCC Meeting, CERN 23 March 2011

  21. results Oscar Adriani LHCC Meeting, CERN 23 March 2011

  22. 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 LHCC Meeting, CERN 23 March 2011

  23. Arm1 and arm2 comparison - Multi-hit rejection and PID correction applied - Energy scale systematic not considered due to strong correlation between Arm1 and Arm2 Deviation in small tower: still unclear, but within systematic errors Oscar Adriani LHCC Meeting, CERN 23 March 2011

  24. Combined spectra and Comparison with models Gray hatched:stat.+syst. errorBlue hatched: QGSJET2 stat. error Arm1 and Arm2 combined spectra including syst. errors Oscar Adriani LHCC Meeting, CERN 23 March 2011

  25. Systematic uncertainties Energy scale, multi-hit, Beam center, PID, luminosity Oscar Adriani LHCC Meeting, CERN 23 March 2011

  26. Systematic Uncertainties Estimated for Arm1 and Arm2 by same methods but independently Estimated by Arm2, and apply it to the both Arm 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 LHCC Meeting, CERN 23 March 2011

  27. 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 LHCC Meeting, CERN 23 March 2011

  28. Beam center position • Error of beam center position is estimated to be 1 mm from comparison between our results and the BPM results • The systematic errors on spectra were estimated from the difference between spectra with 1 mm shift of acceptance cut area. Arm1 Results (Large tower, true single-gamma) (Small tower, true single-gamma) Fluctuation in HE is probably statistical 100 GeV<E<2.5 TeV: 10%E>2.5 TeV: 20% 100 GeV<E<3.5 TeV: 5% Oscar Adriani LHCC Meeting, CERN 23 March 2011

  29. Systematic error from PID Efficiency and purity are estimated with two different approaches Template fitting A: 1 degree of freedom: - Absolute normalization Template fitting B: 3 degrees of freedom: - Absolute normalization - Shift of L90% distribution - Width of L90% distribution Hatched : dataRed : true-gammaBlue : true-hadronGreen : Red+Blue Arm1 Systematic error from PID: 100GeV<E<1.7TeV : 5% 1.7TeV<E : 20% Both on small and large tower Oscar Adriani LHCC Meeting, CERN 23 March 2011

  30. Systematic error from MH True/Reconstructed True/Reconstructed Systematic error is estimated from the deformation factor of original MC spectrum wrtreconstructed MC spectrum for various models Oscar Adriani LHCC Meeting, CERN 23 March 2011

  31. conclusions • LHCf Inclusive photon analysis has been completed • Many detailed systematic checks were necessary! • ‘Very safe’ estimation of systematics • First comparison of variuoshadronic interaction models with experimental data in the most challenging phase space region (8.81 < h < 8.99, h > 10.94) • Other analysis are in progress (hadrons, PT distributions, different h coverage etc.) • We are upgrading the detectors to improve their radiation hardness (GSO scintillators) • Discussion are under way to come back in the TAN for the possible p-Pb run in 2013 (LHCC, Alice, LHC, Atlas etc.) • We will anyway come back for the 14 TeV run with upgraded detector!!!! Oscar Adriani LHCC Meeting, CERN 23 March 2011

  32. A Special thought for japan Oscar Adriani LHCC Meeting, CERN 23 March 2011

  33. Back-up Slides Oscar Adriani LHCC Meeting, CERN 23 March 2011

  34. Xmax = 696.6g/cm2± 2.3+15.9, -7.8g/cm2 systematic statistical Impact of LHCf on CR physics Transition curve for 1017eV proton π0 reconstructed spectrum ⇔ΔXmax(DPMJETⅢ-QGSJETⅡ) = 36g/cm2 Oscar Adriani LHCC Meeting, CERN 23 March 2011

  35. Luminosity during the VDM scans 26th April 2010 9th May 2010 Intensity information Oscar Adriani LHCC Meeting, CERN 23 March 2011

  36. Luminosity errors Total systematic uncertainty due to luminosity was estimated to be 6.1% Oscar Adriani LHCC Meeting, CERN 23 March 2011

  37. 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 LHCC Meeting, CERN 23 March 2011

  38. Energy Reconstruction at SPS Difference of energy reconstruction at SPS between data and MC is < 1%.Systematic error for gain calibration factor layer by layer is 2% Oscar Adriani LHCC Meeting, CERN 23 March 2011

  39. Comparison of EJ260 and GSO-Pulse shape- GSO EJ260 • Response for the N2 (Nitrogen) LASER • pulse width is ~300ps （fast enough） • EJ260 : ~12ns decay time • GSO : 30~40ns decay time • Roughly similar decay time Oscar Adriani LHCC Meeting, CERN 23 March 2011

  40. Comparison of EJ260 and GSO-Radiation Hardness- *HIMAC : Heavy Ion Medical Accelerator in Chiba • EJ260 (HIMAC* Carbon beam)10% decrease of light yield after exposure of 100Gy • GSO (HIMAC Carbon beam)No decrease of light yield even after 7*10^5Gy exposure,BUT increase of light yield is confirmed • The increase depend on irradiation rate (~2.5%/[100Gy/hour]) Oscar Adriani LHCC Meeting, CERN 23 March 2011

  41. Linearity of PMT R7400 • PMTs R7400 are used in current LHCf system • The test was held in HIMAC using Xe beam • PMT R7400 showed good linearity within 1% up to signal level corresponding to 6TeV showerMAX in LHCf. Oscar Adriani LHCC Meeting, CERN 23 March 2011

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