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.
-At the LHC energy of √ s = 7 TeV, under various beam and background conditions, luminosities, and Roman Pot positions, TOTEM has measured the differential cross-section for proton-proton elastic scattering as a function of the four-momentum transfer squared t. The results of the different analyses are in excellent agreement demonstrating no sizeable dependence on the beam conditions. Due to the very close approach of the Roman Pot detectors to the beam center (≈ 5σ beam ) in a dedicated run with β * = 90 m, |t|-values down to 5 · 10 −3 GeV 2 were reached. The exponential slope of the differential elastic cross-section in this newly explored |t|-region remained unchanged and thus an exponential fit with only one constant B = (19.9±0.3) GeV −2 over the large |t|-range from 0.005 to 0.2 GeV 2 describes the differential distribution well. The high precision of the measurement and the large fit range lead to an error on the slope parameter B which is remarkably small compared to previous experiments. It allows a precise extrapolation over the non-visible cross-section (only 9%) to t = 0. With the luminosity from CMS, the elastic crosssection was determined to be (25.4 ± 1.1) mb, and using in addition the optical theorem, the total pp cross-section was derived to be (98.6 ± 2.2) mb. For model comparisons the t-distributions are tabulated including the large |t|-range of the previous measurement (TOTEM Collaboration (Antchev G. et al.), EPL, 95 (2011) 41001).open access
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)
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