207 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 forward photon production cross-section in proton-proton collisions at = 13 TeV with the LHCf detector
In this paper, we report the production cross-section of forward photons in
the pseudorapidity regions of and ,
measured by the LHCf experiment with proton--proton collisions at =
13 TeV. The results from the analysis of 0.191 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
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 neutral pion transverse momentum spectra for = 7TeV proton-proton collisions at LHC
The inclusive production rate of neutral pions in the rapidity range greater
than has been measured by the Large Hadron Collider forward (LHCf)
experiment during LHC \,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.
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
The LHCf experiment at LHC
The LHCf experiment will be installed in 2007 on the LHC collider in the forward direction at ±140m from the ATLAS interaction point. The purpose of LHCf is to precisely measure the pion production cross section near zero degrees through the measurement of the photons produced in neutral pion decay. This measurement is crucial for the simulation of the showers induced in the atmosphere by very high energy cosmic rays; the 14 TeV energy available in the center of mass frame corresponds in fact to an equivalent energy of 1017 eV in the laboratory system. The paper focus on the proposed experiment and on the physics results that we expect from it
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
Transverse single-spin asymmetry for very forward neutral pion production in polarized collisions at GeV
Transverse single-spin asymmetries of very forward neutral pions generated in
polarized collisions allow us to understand the production mechanism in
terms of perturbative and non-perturbative strong interactions. During 2017 the
RHICf Collaboration installed an electromagnetic calorimeter in the zero-degree
region of the STAR detector at the Relativistic Heavy Ion Collider (RHIC) and
measured neutral pions produced at pseudorapidity larger than 6 in polarized
+ collisions at = 510 GeV. The large non-zero asymmetries
increasing both in longitudinal momentum fraction and transverse
momentum have been observed at low transverse momentum
GeV/ for the first time at this collision energy. The asymmetries show an
approximate scaling in the region where non-perturbative
processes are expected to dominate. A non-negligible contribution from soft
processes may be necessary to explain the nonzero neutral pion asymmetries.Comment: This paper submitted to PRL is the final result of arXiv:1902.0785
Forward photon energy spectrum at LHC 7 TeV p-p collisions measured by LHCf
Abstract The LHCf experiment is one of the LHC forward experiments. The aim is to measure the energy and the transverse momentum spectra of photons, neutrons and π 0 's at the very forward region (the pseudo-rapidity range of η > 8.4 ), which should be critical data to calibrate hadron interaction models used in the air shower simulations. LHCf successfully operated at s = 900 GeV and s = 7 TeV proton–proton collisions in 2009 and 2010. We present the first physics result, single photon energy spectra at s = 7 TeV proton–proton collisions and the pseudo-rapidity ranges of η > 10.94 and 8.81 η 8.9 . The obtained spectra were compared with the predictions by several hadron interaction models and the models do not reproduce the experimental results perfectly
First results from LHCf for forward physics in √s = 7TeV proton-proton interactions
The LHCf Collaboration has completed the first step of its scheduled physics program for the study of emission of neutral particles in the forward region of proton-proton (pp) interactions at LHC. Between 2009 and 2010 the LHCf
experiment has successfully taken data at 900 GeV and 7TeV total energy in the center-of-mass frame of reference (CM). After a short presentation of the experimental apparatus, the results for the γ-ray spectrum at √s = 7TeV are presented in this paper
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