The LHCf detector at the CERN Large Hadron Collider

Abstract

LHCf is an experiment dedicated to the measurement of neutral particles emitted in the very forward region of LHC collisions. The physics goal is to provide data for calibrating the hadron interaction models that are used in the study of Extremely High-Energy Cosmic-Rays. This is possible since the laboratory equivalent collision energy of LHC is 10 17 eV. Two LHCf detectors, consisting of imaging calorimeters made of tungsten plates, plastic scintillator and position sensitive sensors, are installed at zero degree collision angle ±140 m from an interaction point (IP). Although the lateral dimensions of these calorimeters are very compact, ranging from 20 mm×20 mm to 40 mm×40 mm, the energy resolution is expected to be better than 6% and the position resolution better than 0.2 mm for γ-rays with energy from 100 GeV to 7 TeV. This has been confirmed by test beam results at the CERN SPS. These calorimeters can measure particles emitted in the pseudo rapidity range η>8.4. Detectors, data acquisition and electronics are optimized to operate during the early phase of the LHC commissioning with luminosity below 10 30 cm −2 s −1 . LHCf is expected to obtain data to compare with the major hadron interaction models within a week or so of operation at luminosity ∼ 10 29 cm −2 s −1 . After ∼10 days of operation at luminosity ∼10 29 cm −2 s −1 , the light output of the plastic scintillators is expected to degrade by ∼10% due to radiation damage. This degradation will be monitored and corrected for using calibration pulses from a laser.

The construction and testing of the silicon position sensitive modules for the LHCf experiment at CERN

“…LHCf [1,2] will make high precision calorimetric measurements of photon and neutron showers taking data at the LHC collider at a centre of mass energy of up to 14 TeV in the very forward region. These data will be used to calibrate Monte Carlo codes that describe the development of showers caused by a cosmic ray hitting the Earth's upper atmosphere, and are currently used by astroparticle physicists.…”

“…One of the calorimeters (ARM1) accomplishes this task by using tightly packed 1mm thick scintillating fibres modules, the other (ARM2, see figure 1) uses instead silicon micro-strip detectors developed for tracking purposes. Only the latter system will be described in this paper while detailed descriptions of the calorimeters and other information on the scintillating fibres modules can be found in [1,2].…”

Search for Dark Matter with ATLAS

“…It studies the structure of the proton while at the same time monitoring the LHC luminosity. Similarly, LHCf [172](LHC forward), is installed 140 m away from the interaction point on both sides of the ATLAS detector. It is intended to study particle cascades similar to cosmic rays that are caused by particles from the proton collisions produced almost collinear to the beam.…”

The performance of the LHCf detector for hadronic showers

“…The LHCf experiment is dedicated to benchmark hadronic interaction models used in cosmic-ray physics [1,2]. It is designed to measure particles emitted in the very forward region (pseudorapidity η > 8.4) of the LHC.…”

“…Scintillation Fiber (SciFi, 1 mm × 1 mm) detectors and silicon strip sensors (160 µm read-out pitch) are used for the position sensors of Arm1 and Arm2, respectively. The details of the LHCf detectors have been previously reported [1,2,6].…”