LHCf Report Takashi SAKO for the LHCf Collaboration 18-Dec-2009 CERN Main Auditorium

What is LHCf?  LHCf determines the energy spectra at zero degree for the calibration of hadron interaction models used in the Cosmic-Ray physics  Small calorimeters are installed either side of IP1 covering η>8.7 (8.4 with crossing angle) ATLAS LHCf Detector 140m away from the interaction point

LHCf Detectors Arm#1 Detector 20mmx20mm+40mmx40mm 4 XY SciFi+MAPMT Arm#2 Detector 25mmx25mm+32mmx32mm 4 XY Silicon strip detectors  Sampling & imaging calorimeters either side of IP1  Two small tower calorimeters in both detectors (Tungsten 44r.l., 1.7λ, 16 plastic scintillator sampling layers, 4 position sensitive layers)

First Events with 900GeV collisions Arm1 (SciFi) Longitudinal development Lateral (X) Distribution Lateral (Y) Distribution

First Events with 900GeV collisions Arm2 (Silicon) Longitudinal development Lateral (X) Distribution Lateral (Y) Distribution

For Physics… Shower Incident position Red: collision + BG Blue: BG only Energy spectrum (to be calibrated to incident energy) Particle ID η=8.7 η=∞ O : collision + BG : BG only Sharp edge at η=8.7 is due to the elliptical beam pipe at D1 magnet between IP and the detector. Good evidence of collision particles!! Compact EM showers

Results with Arm2 Shower Incident positionEnergy spectrum (to be calibrated to incident energy) Particle ID

Summary and Thanks  Successful (almost perfect) commissioning with collision events  Possible to start physics with 6k shower events at 900 GeV collisions  Hope STABLE BEAMS at 2.4TeV collisions in 2010!  Great thanks to CERN, LHC and ATLAS

Backup

LHCf Manipulator  Detectors are 10cm above beam plane during non-STABLE BEAMS  Detectors move down to the beam plane only when STABLE BEAMS are declared

LHCf Aperture