Recent results from LHCf

Abstract

Abstract. The LHCf experiment is one of the LHC forward experiments. The aim of LHCf is to provide critical calibration data of hadronic intraction models used in air shower simulations. The LHCf has completed the operations for p-p collisions with a collision energy of √ s = 0.9 and 7 TeV p-p in 2010 and for p-Pb collisions with a collision energy per nucleon of √ s N N = 5.02. The recent LHCf result of forward neutron energy spectra at 7 TeV p-p collision and forward π 0 spectra at p-Pb collisions are presented in this paper. LHCf experimentThe LHCf experiment is an LHC experiment dedicated to the measurement of very forward neutral-particle spectra. The aim is to provide critical date for the calibration of hadronic interaction models used in MC simulations of cosmic-ray induced air showers. One of the key parameters of air shower development is the energy spectra of the energetic secondaries produced in the forward region of hadronic interactions. The LHCf detectors were designed to measure such forward energetic particles of p-p and pPb collisions at an LHC interaction point. The pseudorapidity coverage of the detectors is more than 8.4 at the beam crossing angle of 140 µrad.The LHCf has two independent detectors, so called Arm1 and Arm2, which were installed +/− 140 m from the ATLAS interaction point (IP1). Each detector has two sampling and imaging calorimeter towers. They consist of tungsten plates, 16 scintillator layers and four position sensitive layers. The scintillator layers were inserted between tungsten plates for shower sampling with 2 radiation length step. The position sensitive layers were developed to measure the shower impact position with different techniques of X-Y scintillating a e-mail: menjo@stelab.nagoya-u.ac.jp fiber hodoscopes and X-Y silicon strip detectors for Arm1 and Arm2, respectively. The transverse cross sections of calorimeters are 20×20 mm 2 and 40×40 mm 2 in Arm1 and 25×25 mm 2 and 32×32 mm 2 in Arm2. The total thickness of calorimeter towers is 44 radiation lengths and 1.7 interaction length. The LHCf detectors are able to measure only neutral particles like photons and neutrons because the charged particles produced at IP1 are swept out by the magnetic field of dipole magnets located between IP1 and the LHCf detectors. The energy resolution of detectors is about 5% for photons and 40% for neutrons. The position resolution is better than 200 µm for photons and a few mm for neutrons. More details of the detector performance were reported elsewhere [1,2].The LHCf has successfully completed operating with proton-proton collisions at √ s = 0.9, 7 TeV in 2010 and with proton-lead collisions at √ s N N = 5.02 TeV in 2013. The forward photon and π 0 spectra for proton-proton collisions has been published [3][4][5]. Neutron spectrum in √ s = 7 TeV p-p collisionsThe measurement of the neutron energy spectrum is a way to access one of the key parameters for air-shower This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which p...

Cosmic rays and hadronic interactions

“…As already discussed, some of the properties of hadronic interactions that are most significant for the [19][20][21] show interesting discrepancies with the available Monte Carlo results. The implication of these results for CR shower development are still not clear, because the data were obtained in a very restricted kinematical region, and the determination of the inclusive energy spectra depends on assumptions about the p ⊥ distributions.…”

Cosmic rays and hadronic interactions

“…The LHCf results Fig. 4 [19][20][21] show interesting discrepancies with the available Monte Carlo results. The implication of these results for CR shower development are still not clear, because the data were obtained in a very restricted kinematical region, and the determination of the inclusive energy spectra depends on assumptions about the p ⊥ distributions.…”