The differential cross sections for inclusive neutral pions as a function of transverse and longitudinal momentum in the very forward rapidity region have been measured at the Large Hadron Collider (LHC) with the Large Hadron Collider forward detector (LHCf) in proton-proton collisions at √ s = 2.76 and 7 TeV and in proton-lead collisions at nucleon-nucleon center-of-mass energies of √ sNN = 5.02 TeV. Such differential cross sections in proton-proton collisions are compatible with the hypotheses of limiting fragmentation and Feynman scaling. Comparing proton-proton with protonlead collisions, we find a sizable suppression of the production of neutral pions in the differential cross sections after subtraction of ultra-peripheral proton-lead collisions. This suppression corre-arXiv:1507.08764v3 [hep-ex]

The purpose of this study was to determine the contribution of different types of retinal neurons to the d-wave of the primate electroretinogram using pharmacological agents. NMDA + TTX was used to suppress inner retinal activity, and APB and PDA to block the activity of the ON- and OFF-pathways, respectively. Results indicated that the inner retinal neurons had a small but certain contribution to the d-wave. The initial rapid phase of the d-wave originates from the activity of the cone OFF-pathway nearly exclusively, and the later slow phase is shaped by the cone photoreceptors. The cone ON-pathway acts in a direction opposite to that of the other components.

In this paper, we report the measurement relative to the production of forward neutrons in proton-proton collisions at √ s = 13 TeV obtained using the LHCf Arm2 detector at the Large Hadron Collider. The results for the inclusive differential production cross section are presented as a function of energy in three different pseudorapidity regions: η > 10.76, 8.99 < η < 9.22 and 8.81 < η < 8.99. The analysis was performed using a data set acquired in June 2015 that corresponds to an integrated luminosity of 0.194 nb −1. The measurements were compared with the predictions of several hadronic interaction models used to simulate air showers generated by Ultra High Energy Cosmic Rays. None of these generators showed good agreement with the data for all pseudorapidity intervals. For η > 10.76, no model is able to reproduce the observed peak structure at around 5 TeV and all models underestimate the total production cross section: among them, QGSJET II-04 shows the smallest deficit with respect to data for the whole energy range. For 8.99 < η < 9.22 and 8.81 < η < 8.99, the models having the best overall agreement with data are SIBYLL 2.3 and EPOS-LHC, respectively: in particular, in both regions SIBYLL 2.3 is able to reproduce the observed peak structure at around 1.5-2.5 TeV.

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The Large Hadron Collider forward (LHCf) experiment was motivated to understand the hadronic interaction processes relevant to cosmic-ray air shower development. We have developed radiation-hard detectors with the use of Gd2SiO5 (GSO) scintillators for proton-proton √s = 13 TeV collisions. Calibration of such detectors for photon measurement has been completed at the CERN SPS T2-H4 line in 2015 using electron beams of 100–250 GeV and muon beams of 150–250 GeV . After the channel-by-channel absolute energy calibration, the energy resolution of the calorimeters is confirmed to be better than 3% for electrons with energy above 100 GeV . The position dependence of the energy scale of the calorimeters was reduced to the level of 1% after the corrections for scintillator nonuniformity and the shower leakage effect. The position resolution of the new shower imaging detector, a GSO-bar hodoscope interleaved in the calorimeter, was 100 μm for 200 GeV electrons. The experimental results are well explained by Monte Carlo simulations. We have confirmed that the new detectors meet the requirement of the LHCf experiment at √s = 13 TeV.

In this paper, we report the measurement of the energy flow, the cross section and the average inelasticity of forward neutrons (+ antineutrons) produced in √ s = 13 TeV proton-proton collisions. These quantities are obtained from the inclusive differential production cross section, measured using the LHCf Arm2 detector at the CERN Large Hadron Collider. The measurements are performed in six pseudorapidity regions: three of them (η > 10.75, 8.99 < η < 9.21 and 8.80 < η < 8.99), albeit with smaller acceptance and larger uncertainties, were already published in a previous work, whereas the remaining three (10.06 < η < 10.75, 9.65 < η < 10.06 and 8.65 < η < 8.80) are presented here for the first time. The analysis was carried out using a data set acquired in June 2015 with a corresponding integrated luminosity of 0.194 nb −1. Comparing the experimental measurements with the expectations of several hadronic interaction models used to simulate cosmic ray air showers, none of these generators resulted to have a satisfactory agreement in all the phase space selected for the analysis. The inclusive differential production cross section for η > 10.75 is not reproduced by any model, whereas the results still indicate a significant but less serious deviation at lower pseudorapidities. Depending on the pseudorapidity region, the generators showing the best overall agreement with data are either SIBYLL 2.3 or EPOS-LHC. Furthermore, apart from the most forward region, the derived energy flow and cross section distributions are best reproduced by EPOS-LHC. Finally, even if none of the models describe the elasticity distribution in a satisfactory way, the extracted average inelasticity is consistent with the QGSJET II-04 value, while most of the other generators give values that lie just outside the experimental uncertainties.

Recently, the RHICf Collaboration measured the transverse single-spin asymmetries of the very forward neutral pion in polarized p+p collisions at √ s = 510 GeV, produced at large pseudorapidity (η 6). The data show large asymmetries both in longitudinal momentum fraction xF and transverse momentum pT at pT < 1 GeV/c. Employing baryonic triple Regge exchanges, we describe the complete RHICf data for the first time and show that the neutral pion production at low pT can be interpreted as a diffractive one.

Precise understanding of hadronic interactions at high energies is a key to improve mass composition measurements of very high energy cosmic-rays and to solve the muon excess issue observed in high energy cosmic-ray experiments using an air-shower technique. The LHCf and RHICf experiments measures the differential production cross sections of very forward neutral particle as photons, neutral pions and neutrons at LHC and RHIC, respectively. These data are critically important to test and tune hadronic interaction models used for air-shower simulations. In this presentation, we introduce the recent results of both the experiments as well as our future operation plans. LHCf published an updated result of forward neutron measurement at pp, √ = 13 TeV. From the observed neutron energy spectra, we also obtained the average inelasticity, which is one of the key parameters for air shower development, as 0.536 +0.031-0.037. In addition, several analysis are on-going; neutral pion measurement at pp, √= 13 TeV, central-forward correlation analysis with LHCf+ATLAS, photon measurement by RHICf. LHCf plans to have operations at and O during the LHC-Run3 period. At pp collisions, new silicon readout system will be introduced to improve the read-out speed, and 10 times more statistics of the previous operation in 2015 will be obtained. Thanks to high statistics, rare particles such as , 0 and Λ will be addressed also. We also plan another operation at RHIC in 2024 with a new detector. The detector, a calorimeter composed of tungsten, Si pad and pixel layers, will have a much wider acceptance and higher sensitivity of 0 measurement than the current detector.