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.

Early results of the LHCf experiment and their contribution to ultra-high-energy cosmic ray physics

LHCf is an experiment dedicated to the measurement of neutral particles emitted in the very forward region of LHC collisions. The physics goal is to provide data for calibrating hadron interaction models that are used in the study of Extremely High-Energy Cosmic-Rays. The LHCf experiment acquired data from April to July 2010 during commissioning time of LHC operations at low luminosity. Production spectra of photons and neutrons emitted in the very forward region (η> 8.4) have been obtained. In this paper preliminary results of the photon spectra taken at s√ = 7TeV are reported

The LHCf detector at the CERN Large Hadron Collider

LHCf is an experiment dedicated to the measurement of neutral particles emitted in the very forward region of LHC collisions. The physics goal is to provide data for calibrating the hadron interaction models that are used in the study of Extremely High-Energy Cosmic-Rays. This is possible since the laboratory equivalent collision energy of LHC is 10(17) eV. Two LHCf detectors, consisting of imaging calorimeters made of tungsten plates, plastic scintillator and position sensitive sensors, are installed at zero degree collision angle +/- 140m from an interaction point (IP). Although the lateral dimensions of these calorimeters are very compact, ranging from 20 mm x 20 mm to 40 mm x 40 mm, the energy resolution is expected to be better than 6% and the position resolution better than 0.2 mm for gamma-rays with energy from 100 GeV to 7 TeV. This has been confirmed by test beam results at the CERN SPS. These calorimeters can measure particles emitted in the pseudo rapidity range eta > 8.4. Detectors, data acquisition and electronics are optimized to operate during the early phase of the LHC commissioning with luminosity below 10(30) cm(-2)S(-1). LHCf is expected to obtain data to compare with the major hadron interaction models within a week or so of operation at luminosity similar to 10(29) cm(-2)s(-1). After similar to 10 days of operation at luminosity similar to 1029 cm(-2)s(-1), the light output of the plastic scintillators is expected to degrade by similar to 10% due to radiation damage. This degradation will be monitored and corrected for using calibration pulses from a laser

The genome landscape of indigenous African cattle

Background: The history of African indigenous cattle and their adaptation to environmental and human selection pressure is at the root of their remarkable diversity. Characterization of this diversity is an essential step towards understanding the genomic basis of productivity and adaptation to survival under African farming systems. Results: We analyze patterns of African cattle genetic variation by sequencing 48 genomes from five indigenous populations and comparing them to the genomes of 53 commercial taurine breeds. We find the highest genetic diversity among African zebu and sanga cattle. Our search for genomic regions under selection reveals signatures of selection for environmental adaptive traits. In particular, we identify signatures of selection including genes and/ or pathways controlling anemia and feeding behavior in the trypanotolerant N’Dama, coat color and horn development in Ankole, and heat tolerance and tick resistance across African cattle especially in zebu breeds. Conclusions: Our findings unravel at the genome-wide level, the unique adaptive diversity of African cattle while emphasizing the opportunities for sustainable improvement of livestock productivity on the continent

Transverse single-spin asymmetry for very forward neutral pion production in polarized p+pp+p collisions at s=510\sqrt{s} = 510 GeV

Transverse single-spin asymmetries of very forward neutral pions generated in polarized $p + p$ 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 $p$+$p$ collisions at $\sqrt{s}$ = 510 GeV. The large non-zero asymmetries increasing both in longitudinal momentum fraction $x_{F}$ and transverse momentum $p_{T}$ have been observed at low transverse momentum $p_{T} < 1$ GeV/$c$ for the first time at this collision energy. The asymmetries show an approximate $x_{F}$ scaling in the $p_{T}$ 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

Comparison of hadron interaction models with measurement of forward spectra by the LHCf apparatus

The LHCf experiment is a forward experiment of LHC. The two LHCf detectors, each composed of a pair of sampling and imaging calorimeters, have been installed at the forward region of IP1 to measure energy and transverse momentum spectra of neutral particles emitted in the very forward region of LHC collisions (η > 8.4). The operation at 900 GeV and 7TeV pp collisions has been completed in the middle of July 2010. We present some preliminary results in this paper

Measurement of very forward particle production at RHIC with √s=510 GeV proton-proton collisions

The Relativistic Heavy Ion Collider forward (RHICf) experiment has measured neutral particles produced in the very forward direction in the √s=510 GeV proton-proton collisions at RHIC in June 2017. The production cross sections of these particles are crucial to understand the hadronic interaction relevant to the air shower development at the cosmic-ray equivalent energy of 1.4×10$^{14}$ eV, just below the energy of the knee. Together with the data at LHC, accelerator data can cover the interaction in the cosmic-ray energy of 10$^{14}$ eV to 10$^{17}$ eV. In addition, RHICf is able to improve the former measurements of single-spin asymmetry in the polarized proton- proton collisions that is sensitive to the fundamental process of the meson exchange. Common data taking with the STAR experiment will shed light on the unexplored low mass diffraction process