2001335 SzGeCERN 20220810145726.0 oai:cds.cern.ch:2001335 cerncds:FULLTEXT cerncds:CERN:FULLTEXT cerncds:CERN DOI 10.1016/j.physletb.2015.09.041 arXiv oai:arXiv.org:1503.03505 Inspire 1351909 arXiv arXiv:1503.03505 hep-ex CERN-PH-EP-DRAFT-LHCF-2015-001 CERN-PH-EP-2015-056 eng CERN Library PH-EP-2015-056 Adriani, O. INFN, Florence Florence U. INFN Section of Florence, Italy University of Florence, Italy Measurement of very forward neutron energy spectra for 7 TeV proton--proton collisions at the Large Hadron Collider 2015-09-19 Geneva CERN 11 Mar 2015 7 p arXiv 10pages, 6 figures takashi.sako@cern.ch takashi.sako@cern.ch cds-ph-ep-publications-referee [CERN] The Large Hadron Collider forward (LHCf) experiment is designed to use the LHC to verify the hadronic-interaction models used in cosmic-ray physics. Forward baryon production is one of the crucial points to understand the development of cosmic-ray showers. We report the neutron-energy spectra for LHC $\sqrt{s}$ = 7 TeV proton--proton collisions with the pseudo-rapidity $\eta$ ranging from 8.81 to 8.99, from 8.99 to 9.22, and from 10.76 to infinity. The measured energy spectra obtained from the two independent calorimeters of Arm1 and Arm2 show the same characteristic feature before unfolding the difference in the detector responses. We unfolded the measured spectra by using the multidimensional unfolding method based on Bayesian theory, and the unfolded spectra were compared with current hadronic-interaction models. The QGSJET II-03 model predicts a high neutron production rate at the highest pseudo-rapidity range similar to our results and the DPMJET 3.04 model describes our results well at the lower pseudo-rapidity ranges. However no model perfectly explains the experimental results in the whole pseudo-rapidity range. The experimental data indicate the most abundant neutron production rate relative to the photon production, which does not agree with predictions of the models. HEPDATA CERN-LHC. The Large Hadron Collider forward (LHCf) experiment is designed to use the LHC to verify the hadronic-interaction models used in cosmic-ray physics. Forward baryon production is one of the crucial points to understand the development of cosmic-ray showers. We report the neutron-energy spectra for LHC $\sqrt{s}$ = 7 TeV proton-proton collisions with the pseudo-rapidity $\eta$ ranging from 8.81 to 8.99, from 8.99 to 9.22, and from 10.76 to infinity. Elsevier The Large Hadron Collider forward (LHCf) experiment is designed to use the LHC to verify the hadronic-interaction models used in cosmic-ray physics. Forward baryon production is one of the crucial points to understand the development of cosmic-ray showers. We report the neutron-energy spectra for LHC $\sqrt{s}$=7 TeV proton–proton collisions with the pseudo-rapidity η ranging from 8.81 to 8.99, from 8.99 to 9.22, and from 10.76 to infinity. The measured energy spectra obtained from the two independent calorimeters of Arm1 and Arm2 show the same characteristic feature before unfolding the detector responses. We unfolded the measured spectra by using the multidimensional unfolding method based on Bayesian theory, and the unfolded spectra were compared with current hadronic-interaction models. The QGSJET II-03 model predicts a high neutron production rate at the highest pseudo-rapidity range similar to our results, and the DPMJET 3.04 model describes our results well at the lower pseudo-rapidity ranges. However, no model perfectly explains the experimental results over the entire pseudo-rapidity range. The experimental data indicate a more abundant neutron production rate relative to the photon production than any model predictions studied here. arXiv The Large Hadron Collider forward (LHCf) experiment is designed to use the LHC to verify the hadronic-interaction models used in cosmic-ray physics. Forward baryon production is one of the crucial points to understand the development of cosmic-ray showers. We report the neutron-energy spectra for LHC $\sqrt{s}$ = 7 TeV proton--proton collisions with the pseudo-rapidity $\eta$ ranging from 8.81 to 8.99, from 8.99 to 9.22, and from 10.76 to infinity. The measured energy spectra obtained from the two independent calorimeters of Arm1 and Arm2 show the same characteristic feature before unfolding the difference in the detector responses. We unfolded the measured spectra by using the multidimensional unfolding method based on Bayesian theory, and the unfolded spectra were compared with current hadronic-interaction models. The QGSJET II-03 model predicts a high neutron production rate at the highest pseudo-rapidity range similar to our results and the DPMJET 3.04 model describes our results well at the lower pseudo-rapidity ranges. However no model perfectly explains the experimental results in the whole pseudo-rapidity range. The experimental data indicate the most abundant neutron production rate relative to the photon production, which does not agree with predictions of the models. preprint CC-BY-4.0 publication CC-BY-4.0 SCOAP3 preprint CERN 2015 publication CERN 2015 Public comments CERN EDS LANL EDS CERN-PH-EP arXiv Particle Physics - Experiment arXiv Nuclear Physics - Experiment CERN QCD CERN forward physics CERN particle and resonance production CERN minimum bias CERN experimental results CERN forward neutron production CERN hadronic-interaction model ARTICLE CERN LHCf_Papers CERN LHC LHCf LANL EDS hep-ex LANL EDS nucl-ex Berti, E. INFN, Florence Florence U. INFN Section of Florence, Italy University of Florence, Italy Bonechi, L. INFN, Florence INFN Section of Florence, Italy Bongi, M. INFN, Florence Florence U. INFN Section of Florence, Italy University of Florence, Italy Castellini, G. INFN, Florence IFAC, Florence INFN Section of Florence, Italy IFAC-CNR, Italy D'Alessandro, R. INFN, Florence Florence U. INFN Section of Florence, Italy University of Florence, Italy Del Prete, M. INFN, Florence Florence U. INFN Section of Florence, Italy University of Florence, Italy Haguenauer, M. Ec. Polytech., Palaiseau (main) Ecole-Polytechnique, France Itow, Y. Nagoya U., Solar-Terrestrial Environ. Lab. KMI, Nagoya Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, Japan Kasahara, K. Waseda U., RISE RISE, Waseda University, Japan Kawade, K. INSPIRE-00419409 Nagoya U., Solar-Terrestrial Environ. Lab. Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Makino, Y. Nagoya U., Solar-Terrestrial Environ. Lab. Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Masuda, K. Nagoya U., Solar-Terrestrial Environ. Lab. Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Matsubayashi, E. Nagoya U., Solar-Terrestrial Environ. Lab. Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Menjo, H. Nagoya U. Graduate School of Science, Nagoya University, Japan Mitsuka, G. Florence U. University of Florence, Italy Muraki, Y. Nagoya U., Solar-Terrestrial Environ. Lab. Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Okuno, Y. Nagoya U., Solar-Terrestrial Environ. Lab. Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Papini, P. INFN, Florence INFN Section of Florence, Italy Perrot, A-L. CERN CERN, Switzerland Ricciarini, S. INFN, Florence IFAC, Florence INFN Section of Florence, Italy IFAC-CNR, Italy Sako, T. Nagoya U., Solar-Terrestrial Environ. Lab. KMI, Nagoya Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, Japan Sakurai, N. KMI, Nagoya Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, Japan Sugiura, Y. Nagoya U., Solar-Terrestrial Environ. Lab. Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Suzuki, T. Waseda U., RISE RISE, Waseda University, Japan Tamura, T. Kanagawa U. Kanagawa University, Japan Tiberio, A. INFN, Florence Florence U. INFN Section of Florence, Italy University of Florence, Italy Torii, S. Waseda U., RISE RISE, Waseda University, Japan Tricomi, A. Catania U. INFN, Catania INFN Section of Catania, Italy University of Catania, Italy Turner, W.C. LBNL, Berkeley LBNL, Berkeley, USA Zhou, Q.D. Nagoya U., Solar-Terrestrial Environ. Lab. Solar-Terrestrial Environment Laboratory, Nagoya University, Japan PH-EP LHCf Collaboration 360-366 Phys. Lett. B 750 2015 https://rivet.hepforge.org/analyses/LHCF_2015_I1351909 Rivet analyses reference 1063119 150650 http://cds.cern.ch/record/2001335/files/arXiv:1503.03505.pdf 1063115 23606 http://cds.cern.ch/record/2001335/files/arm1modelcomp20150125.png 00002 Measured Arm1 energy spectra of neutron-like events together with MC predictions. Left panel shows the results for the small tower, and the center and right panels show the results for the large tower. The vertical bars represent the statistical (they are very small) and systematic uncertainties except the energy scale and luminosity uncertainties. Colored lines indicate MC predictions by EPOS 1.99 (magenta), QGSJET II-03 (blue), SYBILL 2.1 (green), DPMJET 3.04 (red), and PYTHIA 8.145 (yellow). 1063116 23253 http://cds.cern.ch/record/2001335/files/unfA1A2comp8.png 00004 Unfolded energy spectra of the small towers ($\eta>10.76$) and the large towers ($8.99 < \eta<9.22$ and $8.81<\eta<8.99$). The hatched areas show the Arm1 systematic errors, and the bars represent the Arm2 systematic errors except the luminosity uncertainty.. 1063117 28074 http://cds.cern.ch/record/2001335/files/Unfoldedspectra14.png 00005 Comparison of the LHCf results with model predictions at small tower ($\eta>10.76$) and large towers ($8.99 < \eta<9.22$ and $8.81<\eta<8.99$). The black markers and gray hatched areas show the combined results of the LHCf Arm1 and Arm2 detectors and the systematic errors, respectively. 1063118 42813 http://cds.cern.ch/record/2001335/files/UnfoldDemoRatio6.png 00003 Comparison of unfolded spectra with true spectra for DPMJET 3.04 and EPOS 1.99 models at the small tower of Arm1. Bottom panel shows the ratio of the unfolded spectra to the true spectra. 1063120 22280 http://cds.cern.ch/record/2001335/files/A1A2comp8.png 00001 Energy spectra of neutron-like events measured by the Arm1 and Arm2 detectors. The left panel shows the results from the small towers, and the center and right panels show the results for the large towers. The horizontal axes represent the reconstructed energy. The vertical bars represent the statistical (they are negligibly small) and systematic uncertainties except the energy scale and the luminosity uncertainties. 1063121 34297 http://cds.cern.ch/record/2001335/files/L2D_4.png 00000 The L$_{{\rm 2D}}$ parameter distribution for the experimental data and the MC simulations from the template MC. The closed circles represent the Arm1 experimental results, whereas the red and blue histograms correspond to photon and neutron predictions. The open circles is the scaled results of the MC simulation obtained by method A. 1161146 543989 http://cds.cern.ch/record/2001335/files/scoap3-fulltext.pdf Article from SCOAP3 takashi.sako@cern.ch Approval requested for number CERN-PH-EP-2015-056 CERN-PH-EP-2015-056 EPPHAPP 2015-03-03 02:45:37 2015-03-10 02:45:37 takashi.sako@cern.ch waiting Document approved CERN-PH-EP-2015-056 EPPHAPP 2015-03-09 16:33:05 roger.forty@cern.ch approved n 201510 13 LHCf_Papers ARTICLE CERN 1995528