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

O. Adriani, L. Bonechi, M. Bongi, G. Castellini, R. D'Alessandro, A. Faus, K. Fukatsu, M. Haguenauer, Y. Itow, K. Kasahara, K. Kawade, D. Macina, T. Mase, K. Masuda, Y. Matsubara, H. Menjo, G. Mitsuka, Y. Muraki, M. Nakai, K. NodaP. Papini, A. L. Perrot, S. Ricciarini, T. Sako*, Y. Shimizu, K. Suzuki, T. Suzuki, K. Taki, T. Tamura, Shoji Torii, A. Tricomi, W. C. Turner, J. Velasco, A. Viciani, K. Yoshida

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    114 Citations (Scopus)


    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 occurrence of pile-up events), the single photon spectra at √s=7 TeV and pseudo-rapidity (Η) ranges from 8.81 to 8.99 and from 10.94 to infinity were obtained for the first time and are reported in this Letter. 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 2 TeV 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 2 TeV in the rapidity range 8.81<η<8.99.

    Original languageEnglish
    Pages (from-to)128-134
    Number of pages7
    JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
    Issue number2
    Publication statusPublished - 2011 Sept 7


    • Hadron interaction models
    • LHC
    • Ultra-high energy cosmic-ray

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics


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