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The LHCf experiment

The LHCf experiment. Hiroaki MENJO INFN Firenze on behalf for the LHCf collaboration at 29 March 2010, MC4LHC. Outline. What is the LHCf experiment ? - LHCf is one of forward experiments at LHC, with calorimeters covering h>8.4. Why does LHCf look at the very forward region ?

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The LHCf experiment

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  1. The LHCf experiment Hiroaki MENJO INFN Firenze on behalf for the LHCf collaboration at 29 March 2010, MC4LHC

  2. Outline • What is the LHCf experiment ? - LHCf is one of forward experiments at LHC, with calorimeters covering h>8.4. • Why does LHCf look at the very forward region ? - To measure the most energetic secondaries which make an important role in air shower developments of cosmic rays. • What can LHCf measure ? - Energy spectra and PT distribution of neutral particles, gamma-rays, neutrons and p0. LHCf = “LHC forward”

  3. - LHCf collaboration - CMS/TOTEM ALICE LHCb ATLAS 6 countries 12 institutes 31 members LHCf

  4. Detector 140m LHCf Detector(Arm#1) ATLAS TAN 96mm IP 140m 96mm Location Inside of TAN -Neutral particle absorber- LHCf Detector (Arm#2) Detectors at zero degree of collisions Neutral particles charged particles The detector has been installed in 96mm gap of the beam pipes.

  5. 40mm Schematic view of the calorimeters in Arm#1 20mm The Main Calorimeters Two independent calorimeters allow to reconstruct π0 • Sampling Calorimeter • W 44 r.l , 1.7λI • Scintilator x 16 Layers • Position Detector • Scifi x 4 (Arm#1) • Silicon strip detector x 4 (Arm#2) 32mm Schematic view of the calorimeters in Arm#2 25mm Expected Performance: Energy resolution (> 100GeV) < 5% for photons 30% for neutrons Position resolution < 200μm (Arm#1) 40μm (Arm#2)

  6. Arm#1 Arm#2 620mm 620mm 280mm 92mm 90mm 280mm

  7. Detector p,e-,mu Beam test at SPS Energy Resolution for electrons with 20mm cal. • - Electrons 50GeV/c – 200GeV/c • Muons 150GeV/c • Protons 150GeV/c, 350GeV/c Position Resolution (Silicon) Position Resolution (Scifi) σ=172μm for 200GeV electrons σ=40μm for 200GeV electrons

  8. 10m p0 reconstruction at a beam test Fixed Target Arm#1 Detector Acrylic or Carbon ADC counts(0.025pC) Light Intensity(MIPs) p0 mass was reconstructed from gamma-ray pair measured by the both two calorimeters Calibration over SPS energy 70,000 MIPs eq. Response of all PMTs for large amount of light over SPS energy upto 70,000 MIPs eq. (7TeV elemag shower)has been calibrated by a fast N2 laser.

  9. http://op-webtools.web.cern.ch/op-webtools/vistar/vistars.php?usr=LHCFhttp://op-webtools.web.cern.ch/op-webtools/vistar/vistars.php?usr=LHCF Sub detectors -Front Counter- • Thin scintillators with 8x8cm2 acceptance, which have been installed in front of each main detector. Schematic view of Front counter • To monitor beam condition. • For background rejection of beam-residual gas collisions by coincidence analysis

  10. η η Transverse projection of Arm#1 calorimeters at crossing angle of 140urad. Transverse projection of Arm#1 calorimeters at zero-crossing angle. Shadow of beam pipes between IP and TAN neutral beam axis neutral beam axis neutral beam axis Shadow of beam pipes between IP and TAN 8.4 8.7 Shadow of beam pipes between IP and TAN ∞ ∞ Movable detectors Transverse projection of Arm#1 calorimeters

  11. Detectors in LHC IP1,ATLAS Detectors in slots of TANlocated 140m far from IP1

  12. Fe XMAX AGN etc. Proton Proton E=1019eV Photons <XMAX> [g/cm2] Iron 1018eV 1019eV Depth[g/cm2] = Why the very forward region = The motivation comes from observations of Ultra High Energy Cosmic-Rays (UHECRs). -Experiments- AGASA HiRes AUGER TA <Xmax> : one of indicators for cosmic-ray composition ~1020eV EPOS QGSJET2 Phys. Rev. Lett., 2010, 104, 091101

  13. = Why the very forward region = Uncertainty of hadron interaction models induces effective systematic error, especially for composition study of UHECRs. • Total cross section↔ TOTEM, ATLAS(ALFA) • Multiplicity↔ Central detectors • Inelasticity/Secondary spectra↔Forward calorimetersLHCf, ZDCs But now we have LHC to calibrate interaction models at 7+7TeV pp, equivalent to 1017eV in lab. !! Key parameters

  14. Rapidity distributions at 7+7TeV pp = Multiplicity = = Energy Flux = In forward region (h>8.4), • Quite Low multiplicity, but • Covering > 50% of total energy flux. Calculated with DPMJET3, dashed line: neutral particles

  15. XF0.1 1.0 η> 8.4 η> 8.7 Spectra of Secondary gamma-rays Ratio Detectable/All Most of all energetic neutral particle (XF>0.1) are detectable by LHCf

  16. = What can LHCf measure ? = What LHCf can measure Energy spectra and Transverse momentum distribution of Gamma-rays (E>100GeV,DE/E<5%)Neutral Hadrons (E>a few 100 GeV, DE/E~30%)Neutral Pion (E>700GeV, DE/E<3%) at psudo-rapidity range >8.4 LHCf can measure only inclusive spectra !! LHCf trigger is completely independent on ATLAS trigger. However it is possible to identify coincidence events with ATLAS event by offline, and to analyze with center region (ATLAS) in future.

  17. MC model discrimination at 14TeV at 7TeV + 7TeV pp g 106 collisions ↔ 2min. exposure @ 1029cm-2s-1 n w/o resolution n

  18. MC model discrimination at 14TeV 　Reconstruction of p0 Expected Measurement spectrum by Arm1 p0 = PT distribution = 107 collisions ↔ 20min. exposure @ 1029cm-2s-1

  19. MC model discrimination at 7TeV Energy spectra at 3.5TeV + 3.5TeV pp g with 5% energy resolution n with 30% energy resolution 1.5 x 106 collisions ↔ 3min. exposure @ 1029cm-2s-1 We will see 7TeV collisions tomorrow !!

  20. MC model discrimination at 900GeV at 450GeV + 450GeV pp Expected energy spectra with the 20x20mm calorimeterat 107 collisions g DPMJET3 QGSJET2 QGSJET1 SYBILL n w/o resolution w/o resolution Backgrounds We took data in 2009

  21. Preliminary resaults at 900GeV • In last year, LHCf took 6,000 shower events at 900GeV collisions. ↔ > 106collisions at all IPs. Red: colliding bunch= collision + BG Blue: single bunch = BG only Shadow of beam pipes Presented at 18-Dec-2009

  22. Preliminary resaults at 900GeV MC with DPMJET3 Data in 2009 Not calibrated yet preliminary can say nothing about hadron results for the moment ! Checking detector response for hadrons carefully by beam test data. Presented at LHCC 17-Feb-2009 Analysis is ongoing, and we will get more statistic soon !!

  23. Operation Plan We will take data in LHC commissioning phases with low luminosity at every collision energy. + we want to measure at intermediate energy ~1.5+1.5TeV, if LHC has. + we want to measure at light Ions+Ions collisions.

  24. Summary • The LHCf experiment is • one of forward experiments at LHC, with calorimeters covering h>8.4. • LHCf looks at very forward region to measure the most energetic secondaries which play an important role in air shower developments of cosmic rays. • LHCf can measure energy spectra and PT distribution of neutral particles, gamma-rays, neutrons and p0.

  25. Backup

  26. Arm1 g event

  27. Arm2 g event

  28. Arm2 neutron event Transition curve in the calorimetric towers is used to discriminate between g and n g: L90%<20 X0 n: L90%>20 X0

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