Measurement of forward photon production cross-section in proton–proton collisions at [formula omitted] with the LHCf detector

O Adriani,Y Muraki,A Tricomi,T Suzuki,K Masuda,M Ueno,A Tiberio,M Haguenauer,M Shinoda,P Papini,S Ricciarini,M Bongi,K Kasahara,N Sakurai,Y Itow,T Tamura,E Matsubayashi,H Menjo,L Bonechi,R D’alessandro ,Takashi Sako ,Yuya Makino ,Shoji Torii ,E Berti ,W C Turner ,Tadahisa Iwata ,Q Zhou

doi:10.1016/j.physletb.2017.12.050

Abstract

In this paper, we report the production cross-section of forward photons in the pseudorapidity regions of η>10.94 and 8.99>η>8.81, measured by the LHCf experiment with proton–proton collisions at s=13TeV. The results from the analysis of 0.191nb−1 of data obtained in June 2015 are compared to the predictions of several hadronic interaction models that are used in air-shower simulations for ultra-high-energy cosmic rays. Although none of the models agree perfectly with the data, EPOS-LHC shows the best agreement with the experimental data among the models.

Highlights

Hadronic interaction models play an important role in ultra-high energy cosmic-ray (UHECR) observations
They are used in Monte Carlo (MC) simulations of air-shower developments induced by UHECRs, which are one of the key tools used for reconstructing information about primary cosmic rays from observables measured by ground-based detectors
The experiments have published the results of the measured observables which are sensitive to the chemical composition of UHECRs, they have not yet reached any clear conclusions, because of the uncertainty related to the choice of hadronic interaction model [3, 4, 5]

Summary

Introduction

Hadronic interaction models play an important role in ultra-high energy cosmic-ray (UHECR) observations. The major models used in air-shower simulations for UHECRs were re-tuned and updated by taking into account several experimental results obtained from proton–proton collisions with center-of-momentum collision energies of 0.9 and 7 TeV. These models, QGSJET II-04 [7], EPOS-LHC [8], and SIBYLL 2.3 [9], are called the post-LHC models. Each of the two detectors, Arm and Arm, has two calorimeter towers with acceptances of 20 mm × 20 mm and 40 mm × 40 mm (Arm1), and 25 mm × 25 mm and 32 mm × 32 mm (Arm2) This double-calorimeter configuration allows the photon pairs to be detected from the decay of π0 and η mesons with threshold energies of 600 GeV and 2.2 TeV, respectively. The trigger efficiency was 100% for photons with energies greater than 200 GeV

MC Simulation

Analysis

Energy scale

Results

Summary