6 research outputs found
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
Measurement of zero degree inclusive photon energy spectra for 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 900 GeV are reported. The results from the analysis
of 0.30 of data collected in May 2010 in the two
pseudorapidity regions of and 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 7 TeV collisions
Recent results from LHCf
The Large Hadron Collider forward experiment measured very forward neutral particle spectra in LHC proton-proton collisions in early 2010. In this paper we will discuss the energy and transverse momentum spectra of neutral pion at the 7TeV proton-proton collision, and the inclusive photon energy spectra taken at the 900GeV collisions. The spectra in both collision energies 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