Measurement of zero degree single photon energy spectra for sqrt(s) = 7TeV proton-proton collisions at LHC

In early 2010, the Large Hadron Collider forward (LHCf) experiment measured very forward neutral particle spectra in LHC proton-proton collisions. From a limited data set taken under the best beam conditions (low beam-gas background and low occurance of pile-up events), the single photon spectra at sqrt(s)=7TeV and pseudo-rapidity (eta) ranges from 8.81 to 8.99 and from 10.94 to infinity were obtained for the first time and are reported in this paper. The spectra from two independent LHCf detectors are consistent with one another and serve as a cross check of the data. The photon spectra are also compared with the predictions of several hadron interaction models that are used extensively for modeling ultra high energy cosmic ray showers. Despite conservative estimates for the systematic errors, none of the models agree perfectly with the measurements. A notable difference is found between the data and the DPMJET 3.04 and PYTHIA 8.145 hadron interaction models above 2TeV where the models predict higher photon yield than the data. The QGSJET II-03 model predicts overall lower photon yield than the data, especially above 2TeV in the rapidity range 8.81<eta<8.99

The performance of the LHCf detector for hadronic showers

The Large Hadron Collider forward (LHCf) experiment has been designed to use the LHC to benchmark the hadronic interaction models used in cosmic-ray physics. The LHCf experiment measures neutral particles emitted in the very forward region of LHC collisions. In this paper, the performances of the LHCf detectors for hadronic showers was studied with MC simulations and beam tests. The detection efficiency for neutrons is from 60% to 70% above 500 GeV. The energy resolutions are about 40% and the position resolution is 0.1 to 1.3mm depend on the incident energy for neutrons. The energy scale determined by the MC simulations and the validity of the MC simulations were examined using 350 GeV proton beams at the CERN-SPS.Comment: 15pages, 19 figure

Measurement of forward photon production cross-section in proton-proton collisions at s\sqrt{s} = 13 TeV with the LHCf detector

In this paper, we report the production cross-section of forward photons in the pseudorapidity regions of $\eta\,>\,10.94$ and $8.99\,>\,\eta\,>\,8.81$, measured by the LHCf experiment with proton--proton collisions at $\sqrt{s}$ = 13 TeV. The results from the analysis of 0.191 $\mathrm{nb^{-1}}$ 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.Comment: 21 pages, 4 figure

Measurement of forward neutral pion transverse momentum spectra for s\sqrt{s} = 7TeV proton-proton collisions at LHC

The inclusive production rate of neutral pions in the rapidity range greater than $y=8.9$ has been measured by the Large Hadron Collider forward (LHCf) experiment during LHC $\sqrt{s}=7$\,TeV proton-proton collision operation in early 2010. This paper presents the transverse momentum spectra of the neutral pions. The spectra from two independent LHCf detectors are consistent with each other and serve as a cross check of the data. The transverse momentum spectra are also compared with the predictions of several hadronic interaction models that are often used for high energy particle physics and for modeling ultra-high-energy cosmic-ray showers.Comment: 18 Pages, 10 figures, submitted to Phys. Rev.

Developing a High Resolution ZDC for the EIC

The Electron Ion Collider offers the opportunity to make un-paralleled multidimen- sional measurements of the spin structure of the proton and nuclei, as well as a study of the onset of partonic saturation at small Bjorken-x [1]. An important requirement of the physics program is the tagging of spectator neutrons and the identification of forward photons. We propose to design and build a Zero Degree Calorimeter, or ZDC, to measure photons and neutrons with excellent energy & position resolution

Measurement of zero degree inclusive photon energy spectra for s=\sqrt{s}= 900 GeV proton-proton collisions at LHC

The inclusive photon energy spectra measured by the Large Hadron Collider forward (LHCf) experiment in the very forward region of LHC proton-proton collisions at $\sqrt{s}=$ 900 GeV are reported. The results from the analysis of 0.30 $\mathrm{nb^{-1}}$ of data collected in May 2010 in the two pseudorapidity regions of $\eta > 10.15$ and $8.77 < \eta < 9.46$ are compared with the predictions of the hadronic interaction models DPMJET 3.04, EPOS 1.99, PYTHIA 8.145, QGSJET I -.1em I-03 and SIBYLL 2.1, which are widely used in ultra-high-energy cosmic-ray experiments. EPOS 1.99 and SYBILL 2.1 show a reasonable agreement with the spectral shape of the experimental data, whereas they predict lower cross-sections than the data. The other models, DPMJET 3.04, QGSJET I -.1em I-03 and PYTHIA 8.145, are in good agreement with the data below 300 GeV but predict harder energy spectra than the data above 300 GeV. The results of these comparisons exhibited features similar to those for the previously reported data for $\sqrt{s}=$ 7 TeV collisions