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LHCf: Primi risultati dei runs a 900 GeV

LHCf: Primi risultati dei runs a 900 GeV. Oscar Adriani Università degli Studi di Firenze INFN Sezione di Firenze. Experimental set-up. Detector I Tungsten Scintillator Scintillating fibers. Detector II Tungsten Scintillator Silicon m strips. I NTERACTION POINT IP1 (ATLAS).

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LHCf: Primi risultati dei runs a 900 GeV

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  1. LHCf:Primi risultati dei runs a 900 GeV Oscar Adriani Università degli Studi di Firenze INFN Sezione di Firenze

  2. Experimental set-up Detector I Tungsten Scintillator Scintillating fibers Detector II Tungsten Scintillator Silicon mstrips INTERACTION POINT IP1 (ATLAS) Protons Charged particles Neutral particles 140 m 140 m Beam pipe Beam line Detectors installed in the TAN region, 140 m away from the Interaction Point 1 • Here the beam pipe splits in 2 separate tubes. • Charged particle are swept away by magnets • We cover up to y Oscar Adriani Roma, 26/01/10

  3. LHCf : Monte Carlo discrimination 106 generated LHC interactions  1 minute exposure@1029 cm-2s-1 luminosity Oscar Adriani Roma, 26/01/10

  4. p0 spectra 10mm Lower Gamma2 E2 Gamma1 E1 Emin~ 700GeV Geometrical Acceptance Peak : 134MeV Sigma: 4.9MeV Cut: 125-145MeV p0 produced at collision can be extracted by using gamma pair events Powerful tool to calibrate the energy scale and also to eliminate beam-gas BG Oscar Adriani Roma, 26/01/10

  5. 2009 LHC Operation: Good News! • From End of October 2009 LHC restarted operation • 450 GeV + 450 GeV  1.2 TeV + 1.2 TeV • Exceptional effort and success from LHC!!! • Few weeks of ‘smooth’ running allowed LHCf to collect some statistics at 450+450 GeV in stable beam conditions (Moving from garage to running position)     • Extremely useful period to debug all the system • No particular problem came out from the run • Detectors are working very well and in a stable way Oscar Adriani Roma, 26/01/10

  6. Pedestals and Sigma for silicon Oscar Adriani Roma, 26/01/10

  7. Stability of pedestal of Silicon In run (2265-2267), > 2000. At that time, we found Agilent1 was broken operation for collision Gain mode was change from high to low. Very stable during the stable operation. Oscar Adriani Roma, 26/01/10

  8. 2009 LHC Operation: Not so good news… • No stable beam at 1.2+1.2 TeV  No data at this energy for this year  • No p0 reconstructed in LHCf (Ecmthr  2 TeV) • Neutral particle flux in LHCf region scale as E3 • Flux is reduced by (7 TeV/450 GeV)3 4.104 wrt to 7+7 TeV expectations • Luminosity  1026 cm-2s-1 • 3 orders of magnitude below ‘optimal LHCf low luminosity’) • 20 minutes lost at beginning of stable beam to allow moving from garage to operating positions (already improved for 2010 run) •  Very low statistics •  24 hours data taking •  104 particles less than ‘usual LHCf plot’ Oscar Adriani Roma, 26/01/10

  9. Number of detected showers > 6000! Run table for 2009 (Stable beam) Oscar Adriani Roma, 26/01/10

  10. Dedicated LHCf page on VISTAR Oscar Adriani Roma, 26/01/10

  11. Oscar Adriani Roma, 26/01/10

  12. Arm1 g event Oscar Adriani Roma, 26/01/10

  13. Arm2 g event Oscar Adriani Roma, 26/01/10

  14. Arm2 neutron event Transition curve in the calorimetric towers is used to discriminate between g and n L90%<20 X0 Oscar Adriani Roma, 26/01/10

  15. Arm2 analysis (Fully Italian analysis) • Results are preliminary • Big effort to understand the LHC beam (DIP signals) • Intensity bunch by bunch • Not colliding bunches vs colliding bunches to estimate Beam Gas rate • Timing of the bunches • Etc etc etc • Quite few problems found during the analysis • Timing problems in Atlas (BPTX not synchronized) • Displaced bunches • Missing DIP information • Etc etc etc Oscar Adriani Roma, 26/01/10

  16. Statistics • Integrated Intensity after bad runs cuts= (SbunchIntensity ) x time [sec] • Number of Events in Arm2 Before cuts : 3,656L2TA events, After bad run cuts : 2,000L2TA events (55% efficiency) *) L2TA : Hardware Trigger for showers *) Criteria : integrated energy deposit in calorimeter > 400MIPs g : L90 < 20r.l., h: L90 > 20r.l Oscar Adriani Roma, 26/01/10

  17. Hit map on ARM2 (Silicon data) Oscar Adriani Roma, 26/01/10

  18. Transverse projection in TAN slot Oscar Adriani Roma, 26/01/10

  19. Hit distributions on the 4 Si Layers Y1 X1 Y2 X2 Y3 X3 Y4 X4 Oscar Adriani Roma, 26/01/10

  20. X-Y silicon energy correlation Oscar Adriani Roma, 26/01/10

  21. Analysis method for g and n • Position search : Strip with the biggest dE • Criteria of event cuts : • Integral energy deposit in one tower : > 400 MIPS • Position cuts for gamma-rays : 2 mm inside from the tower edges. • PID : Gamma-rays: L90 < 20r.l. Hadrons: L90 < 20r.l Oscar Adriani Roma, 26/01/10

  22. Neutrons Photons L20 and L90 • Integrate the energy loss in the calorimeter layers, normalized to the total energy • L20 (L90) depth at which we have 20% (90%) of integrated energy dE ∑i<z(dE)/Etot L20 Oscar Adriani Roma, 26/01/10

  23. PID L20 vs L90 Criteria : Sum dE > 400MIPs it correspond to about 10GeV gamma-ray equivalent energy Oscar Adriani Roma, 26/01/10

  24. Distribution of integrated dE • Raw level spectra (no PID and combined 25mm and 32mm) Bunch Crossing : No normalization Non-Bunch Crossing: Normalized by Integral Intensity. (normalization factor = 9.0E14/7.5E14) Oscar Adriani Roma, 26/01/10

  25. Energy spectra for gamma-rays Spectra in B.C. and Non-B.C Spectra After subtraction of Non-B.C. Oscar Adriani Roma, 26/01/10

  26. Energy spectra for hadrons Spectra in B.C. and Non-B.C No cut dedicated for hadron energy reconstruction (like early interaction events) x-axis is not real energy of hadrons  calibration is necessary Spectra After subtraction of Non-B.C. Oscar Adriani Roma, 26/01/10

  27. Comparison 25mm and 32mm Chi2 : 13.3 (DOF=10) Chi2 : 7.7 (DOF=10) The spectra of 32 mm are normalized by the relative acceptance (factor 1.77) No significant difference between 25mm and 32mm spectra. It is consistent with the expectation by simulation (Flat distributions at 450 GeV) Oscar Adriani Roma, 26/01/10

  28. Arm1 (Japanese analysis) The Beam Pipe profile is clearly seen Oscar Adriani Roma, 26/01/10

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  31. Plans for the future • At beginning of 2010, when LHC will restart, we will take data • 1.2+1.2 TeV • 3.5+3.5 TeV • When luminosity will become too high (>1031 cm-2s-1, 2 pb-1) we will go out from the TAN (Radiation damage of the plastic scintillator is significant, LHCf has been designed to run at low luminosity/high energy!) • Test beam for calibration with the ‘old’ LHCf • Replace Plastic Scintillator with GSO + Change position of silicon layers • Test beam with ‘new’ LHCf (Summer 2010) • Re-install LHCf when LHC will increase energy Oscar Adriani Roma, 26/01/10

  32. Backup slides Oscar Adriani Roma, 26/01/10

  33. PID sum dE v.s. L90 Black points : bunch crossing, Red points: non-b.c. Concentrated around low sum dE and high L90.To understand what makes this feature, need more analysis.(low energy hadron events , pedestal fluctuation etc.) Oscar Adriani Roma, 26/01/10

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  36. g and n spectra at different energies 20 min @ 1029 cm-2s-1 1 min @ 1029 cm-2s-1 1 min @ 1029 cm-2s-1 450 GeV 1 TeV 5 TeV g g g 20 min @ 1029 cm-2s-1 1 min @ 1029 cm-2s-1 1 min @ 1029 cm-2s-1 5 TeV 450 GeV 1 TeV n n n DPMJET3 QGSJET2 QGSJET1 SIBYLL No detector resolution taken into account Oscar Adriani Roma, 26/01/10

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