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

Measurements of very forward particles production spectra at LHC: the LHCf experiment

International audienceThanks to two small sampling calorimeters installed in the LHC tunnel at ±140 m from IP1, the LHC forward (LHCf) experiment is able to detect neutral particles produced by high energy proton-ion collisions in the very forward region (pseudo-rapidity η > 8.4). The main aim of LHCf is to provide precise measurements of the production spectra relative to these particles, in order to tune hadronic interaction models used by ground-based cosmic rays experiments. In this paper we will present the current status of the LHCf experiment, regarding in particular collected data and analysis results, as well as future prospect

Results from the LHCf Run II in proton-proton collisions at s\sqrt{s} = 13 TeV

International audienceThe LHCf experiment, at the Large Hadron Collider (LHC), consists of two small independent calorimeters placed 140 metres away, on opposite sides of the ATLAS interaction point (IP1). LHCf has the capability to measure zero-degree neutral particles, covering the pseudorapidity region above 8.4. By measuring the very-forward particle production rates at the highest energy possible at an accelerator, LHCf aims to improve our understanding of hadronic interactions in air-showers induced by ultra-high-energy cosmic rays in the atmosphere. This contribution will highlight recent results from Run II measurements with p-p collisions at 13 TeV. At first, the advantages of an ATLAS-LHCf combined analysis are discussed and a preliminary energy spectrum of very-forward photons produced in diffractive collisions as tagged by ATLAS is shown. The neutron energy spectrum measurements, for several pseudorapidity regions, are presented and compared with the predictions of various hadronic interaction models. From these measurements the average inelasticity of the collisions, which strongly affects the development of an air-shower, has also been extracted. Finally, the preliminary $\pi^0$ Feynman-x and transverse momentum spectra, which affect the development of the electromagnetic component of an air-shower, are shown

Very-forward π0\pi^0 production cross section in proton-proton collisions at s\sqrt {s} = 13 TeV measured with the LHCf experiment

The LHCf experiment, situated at the LHC accelerator, is composed of two independent detectors located at 140 metres from the ATLAS interaction point (IP1) on opposite sides along the beam axis. LHCf covers the pseudorapidity region above 8.4, with the capability to measure zero-degree neutral particles. The physics motivation of the experiment is to test the hadronic interaction models commonly used in ground-based cosmic rays experiments to simulate air-showers induced by ultra-high-energy cosmic rays (UHECR) in the Earth atmosphere. The data from accelerator experiments are very important for the tuning of these phenomenological models in order to reduce the systematic uncertainty of UHECR measurements. A precise measurement of the $\pi^0$s produced in the very-forward region in high energy collisions provides the possibility to study the electromagnetic component of secondary particles produced in the first interaction of a UHECR with the atmosphere. In this contribution the preliminary results from the $\pi^0$ analysis of the data acquired in proton-proton collisions at $\sqrt{s}$ = 13 TeV will be presented. The Feynman-x and transverse momentum spectra obtained with the two detectors will be compared to show the consistency of the results

LHCf plan for proton-oxygen collisions at LHC

International audienceThe LHCf experiment is designed to provide precise measurements of very forward neutral particle production from high energy proton-proton, proton-ion and ion-ion collisions. This information is necessary to test and tune hadronic interaction models used by ground-based cosmic rays experiments to extract the average composition of Ultra High Energy Cosmic Rays. In order to reach this goal, LHCf makes use of two small sampling calorimeters installed in the LHC tunnel at $\pm 140$ m from Interaction Point 1, both able to detect neutral particles having pseudo-rapidity $\eta > 8.4$. In LHC Run I and II, the LHCf experiment acquired data relative to p-p collisions at $\sqrt{s} =$ 0.9, 2.76, 7 and 13 TeV, and p-Pb collisions at $\sqrt{s_{NN}} =$ 5.02 and 8.16 TeV. Forward production from p-p and p-Pb collisions are not directly applicable to the tuning of the model used to simulate extensive air showers, since the first interaction between a cosmic ray and an atmospheric nucleus generally involves a light nucleus, like N or O. In LHC Run III, we will have the unique opportunity to directly measure forward production from high energy p-O collisions, without the need to obtain this information by interpolating the measurements from p-p and p-Pb collisions. In this contribution, we discuss the importance of such a measurement, focusing on all the benefits in terms of a more direct and complete input for model tuning, and on the operation plans, including the importance to take data both from high energy p-O and O-O collisions

Latest results from the LHCf Experiment

The LHC forward (LHCf) is a small experiment at the LHC designed to measure neutral particles emitted in the very forward region (pseudo-rapidity h > 8 : 4). It has measured proton–proton col- lisions at p s = 0 : 9 ; 2 : 76 ; 7 and 13 TeV, and proton–lead collisions at p s NN = 5 : 02 and 8.16 TeV. Its main purpose is to provide precise measurements of the production spectra of these forward particles, in order to calibrate hadronic interaction models used in air shower observations. In this paper we will present the current status of the LHCf experiment, regarding in particular collected data and analysis results, as well as future prospects