Pseudorapidity (η) distributions of charged particles produced in proton-proton collisions at a centre-of-mass energy of 8 TeV are measured in the ranges |η| < 2.2 and 5.3 < |η| < 6.4 covered by the CMS and TOTEM detectors, respectively. The data correspond to an integrated luminosity of L = 45 µb −1 . Measurements are presented for three event categories. The most inclusive category is sensitive to 91-96 % of the total inelastic proton-proton cross section. The other two categories are disjoint subsets of the inclusive sample that are either enhanced or depleted in single diffractive dissociation events. The data are compared to models used to describe high-energy hadronic interactions. None of the models considered provide a consistent description of the measured distributions.

The TOTEM experiment has made a precise measurement of the elastic proton-proton differential cross-section at the centre-of-mass energy √ s = 8 TeV based on a high-statistics data sample obtained with the β * = 90 m optics. Both the statistical and systematic uncertainties remain below 1 %, except for the t-independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of fourmomentum transfer squared 0.027 < |t| < 0.2 GeV 2 with a significance greater than 7 σ. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. Using them for the differential cross-section extrapolation to t = 0, and further applying the optical theorem, yields total cross-section estimates of (101.5 ± 2.1) mb and (101.9 ± 2.1) mb, respectively, in agreement with previous TOTEM measurements.This article is dedicated to the memory of Prof. E. Lippmaa and Prof. M. Lo Vetere who passed away recently

This paper describes the design and the performance of the timing detector developed by the TOTEM Collaboration for the Roman Pots (RPs) to measure the Time-Of-Flight (TOF) of the protons produced in central diffractive interactions at the LHC. The measurement of the TOF of the protons allows the determination of the longitudinal position of the proton interaction vertex and its association with one of the vertices reconstructed by the CMS detectors. The TOF detector is based on single crystal Chemical Vapor Deposition (scCVD) diamond plates and is designed to measure the protons TOF with about 50 ps time precision. This upgrade to the TOTEM apparatus will be used in the LHC run 2 and will tag the central diffractive events up to an interaction pileup of about 1. A dedicated fast and low noise electronics for the signal amplification has been developed. The digitization of the diamond signal is performed by sampling the waveform. After introducing the physics studies that will most profit from the addition of these new detectors, we discuss in detail the optimization and the performance of the first TOF detector installed in the LHC in November 2015.

Luminosity-independent measurements of total, elastic and inelastic cross-sections at √ s = 7 TeVThe TOTEM Collaboration G. Antchev a) , P. Aspell 8) , I. Atanassov 8,a) , V. Avati 8) , J. Baechler 8) , V. Berardi 5b,5a) , M. Berretti 7b) , E. Bossini 7b) , M. Bozzo 6b,6a) , P. Brogi 7b) , E. Brücken 3a,3b) , A. Buzzo 6a) , F. S. Cafagna 5a) , M. Calicchio 5b,5a) , M. G. Catanesi 5a) , C. Covault 9) , M. Csanád 4,e) , T. Csörgő 4) , M. Deile 8) , M. Doubek 1b) , K. Eggert 9) , V. Eremin b) , R. Ferretti 6a,6b) , F. Ferro 6a) , A. Fiergolski c) , F. Garcia 3a) , S. Giani 8) , V. Greco 7b,8) , L. Grzanka 8,d) , J. Heino 3a) , T. Hilden 3a,3b) , R. A. Intonti 5a) , J. Kašpar 1a,8) , J. Kopal 1a,8) , V. Kundrát 1a) , K. Kurvinen 3a) , S. Lami 7a) , G. Latino 7b) , R. Lauhakangas 3a) , T. Leszko c) , E. Lippmaa 2) , M. Lokajíček 1a) , M. Lo Vetere 6b,6a) , F. Lucas Rodríguez 8) , M. Macrí 6a) , T. Mäki 3a) , A. Mercadante 5b,5a) , N. Minafra 8) , S. Minutoli 6a) , F. Nemes 4,e) , H. Niewiadomski 8) , E. Oliveri 7b) , F. Oljemark 3a,3b) , R. Orava 3a,3b) , M. Oriunno 8,f) , K.Österberg 3a,3b) , P. Palazzi 7b) , J. Procházka 1a) , M. Quinto 5a) , E. Radermacher 8) , E. Radicioni 5a) , F. Ravotti 8) , E. Robutti 6a) , L. Ropelewski 8) , G. Ruggiero 8) , H. Saarikko 3a,3b) , A. Santroni 6b,6a) , A. Scribano 7b) , J. Smajek 8) , W. Snoeys 8) , J. Sziklai 4) , C. Taylor 9) , N. Turini 7b) , V. Vacek 1b) , M. Vítek 1b) , J. Welti 3a,3b) J. Whitmore 10) and P. Wyszkowski 8,g)

Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at √ s = 7 TeV in dedicated runs with the Roman Pot detectors placed as close as seven times the transverse beam size (σ beam ) from the outgoing beams. After careful study of the accelerator optics and the detector alignment, |t| , the square of four-momentum transferred in the elastic scattering process, has been determined with an uncertainty of δt = 0.1 GeV |t|. In this letter, first results of the differential cross section are presented covering a |t|-range from 0.36 to 2.5 GeV 2 . The differential cross-section in the range 0.36 < |t| < 0.47 GeV 2 is described by an exponential with a slope parameter B = (23.6 ± 0.5 stat ± 0.4 syst ) GeV −2 , followed by a significant diffractive minimum at |t| = (0.53 ± 0.01 stat ± 0.01 syst ) GeV 2 . For |t|-values larger than ∼ 1.5 GeV 2 , the cross-section exhibits a power law behaviour with an exponent of -7.8 ± 0.3 stat ± 0.1 syst . When compared to predictions based on the different available models, the data show a strong discriminative power despite the small t-range covered.

The TOTEM collaboration has measured the elastic proton-proton differential cross section dσ/dt at √ s = 13 TeV LHC energy using dedicated β * = 90 m

The TOTEM collaboration has measured the proton-proton total cross section at ffiffi ffi s p ¼ 8 TeV using a luminosity-independent method. In LHC fills with dedicated beam optics, the Roman pots have been inserted very close to the beam allowing the detection of $90% of the nuclear elastic scattering events. Simultaneously the inelastic scattering rate has been measured by the T1 and T2 telescopes. By applying the optical theorem, the total proton-proton cross section of ð101:7 AE 2:9Þ mb has been determined, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections: el ¼ ð27:1 AE 1:4Þ mb; inel ¼ ð74:7 AE 1:7Þ mb.

The TOTEM experiment at the LHC has performed the first measurement at $$\sqrt{s} = 13\,\mathrm{TeV}$$s=13TeV of the $$\rho $$ρ parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at $$t=0$$t=0, obtaining the following results: $$\rho = 0.09 \pm 0.01$$ρ=0.09±0.01 and $$\rho = 0.10 \pm 0.01$$ρ=0.10±0.01, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the $$\rho $$ρ measurement, combined with the TOTEM total cross-section measurements in an energy range larger than $$10\,\mathrm{TeV}$$10TeV (from 2.76 to $$13\,\mathrm{TeV}$$13TeV), has implied the exclusion of all the models classified and published by COMPETE. The $$\rho $$ρ results obtained by TOTEM are compatible with the predictions, from other theoretical models both in the Regge-like framework and in the QCD framework, of a crossing-odd colourless 3-gluon compound state exchange in the t-channel of the proton–proton elastic scattering. On the contrary, if shown that the crossing-odd 3-gluon compound state t-channel exchange is not of importance for the description of elastic scattering, the $$\rho $$ρ value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-|t| reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton–proton cross-section measurement $$\sigma _{\mathrm{tot}} = (110.3 \pm 3.5)\,\mathrm{mb}$$σtot=(110.3±3.5)mb, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields $$\sigma _{\mathrm{tot}} = (110.5 \pm 2.4)\,\mathrm{mb}$$σtot=(110.5±2.4)mb.