Measurement of the forward charged particle pseudorapidity density in pp collisions at  TeV using a displaced interaction point - TOTEM Collaboration

G. Antchev; P. Aspell; I. Atanassov; V. Avati; J. Baechler; V. Berardi; M. Berretti; E. Bossini; U. Bottigli; M. Bozzo; E. Brücken; A. Buzzo; F. S. Cafagna; M. G. Catanesi; C. Covault; M. Csanád; T. Csörgő; M. Deile; M. Doubek; K. Eggert; V. Eremin; F. Ferro; A. Fiergolski; F. Garcia; V. Georgiev; S. Giani; L. Grzanka; J. Hammerbauer; J. Heino; T. Hilden; A. Karev; J. Kašpar; J. Kopal; V. Kundrát; S. Lami; G. Latino; R. Lauhakangas; T. Leszko; E. Lippmaa; J. Lippmaa; M. V. Lokajíček; L. Losurdo; M. Lo Vetere; F. Lucas Rodríguez; M. Macrí; T. Mäki; A. Mercadante; N. Minafra; S. Minutoli; F. Nemes; H. Niewiadomski; E. Oliveri; F. Oljemark; R. Orava; M. Oriunno; K. Österberg; P. Palazzi; Z. Peroutka; J. Procházka; M. Quinto; E. Radermacher; E. Radicioni; F. Ravotti; E. Robutti; L. Ropelewski; G. Ruggiero; H. Saarikko; A. Scribano; J. Smajek; W. Snoeys; T. Sodzawiczny; J. Sziklai; C. Taylor; N. Turini; V. Vacek; J. Welti; J. Whitmore; P. Wyszkowski; K. Zielinski

doi:10.1140/epjc/s10052-015-3343-7

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2015) 75: 126
https://doi.org/10.1140/epjc/s10052-015-3343-7

Regular Article - Experimental Physics

Measurement of the forward charged particle pseudorapidity density in pp collisions at $\sqrt{s} = 8$ TeV using a displaced interaction point

TOTEM Collaboration

G. Antchev¹⁷, P. Aspell¹³, I. Atanassov¹³^,17, V. Avati¹³, J. Baechler¹³, V. Berardi⁷^,8, M. Berretti¹²^,13^*, E. Bossini¹², U. Bottigli¹², M. Bozzo⁹^,10, E. Brücken⁴^,5, A. Buzzo⁹, F. S. Cafagna⁷, M. G. Catanesi⁷, C. Covault¹⁴, M. Csanád⁶^,21, T. Csörgő⁶, M. Deile¹³, M. Doubek², K. Eggert¹⁴, V. Eremin¹⁸, F. Ferro⁹, A. Fiergolski⁷^,19, F. Garcia⁴, V. Georgiev¹⁶, S. Giani¹³, L. Grzanka¹⁵^,20, J. Hammerbauer¹⁶, J. Heino⁴, T. Hilden⁴^,5, A. Karev¹³, J. Kašpar¹^,13, J. Kopal¹^,13, V. Kundrát¹, S. Lami¹¹, G. Latino¹², R. Lauhakangas⁴, T. Leszko¹⁹, E. Lippmaa³, J. Lippmaa³, M. V. Lokajíček¹, L. Losurdo¹², M. Lo Vetere⁹^,10, F. Lucas Rodríguez¹³, M. Macrí ⁹, T. Mäki⁴, A. Mercadante⁷, N. Minafra⁸^,13, S. Minutoli⁹, F. Nemes⁶^,21, H. Niewiadomski¹³, E. Oliveri¹², F. Oljemark⁴^,5, R. Orava⁴^,5, M. Oriunno²², K. Österberg⁴^,5, P. Palazzi¹², Z. Peroutka¹⁶, J. Procházka¹, M. Quinto⁷^,8, E. Radermacher¹³, E. Radicioni⁷, F. Ravotti¹³, E. Robutti⁹, L. Ropelewski¹³, G. Ruggiero¹³, H. Saarikko⁴^,5, A. Scribano¹², J. Smajek¹³, W. Snoeys¹³, T. Sodzawiczny¹³, J. Sziklai⁶, C. Taylor¹⁴, N. Turini¹², V. Vacek², J. Welti⁴^,5, J. Whitmore²³, P. Wyszkowski¹⁵ and K. Zielinski¹⁵

¹ Institute of Physics of the Academy of Sciences of the Czech Republic, Prague, Czech Republic
² Czech Technical University, Prague, Czech Republic
³ National Institute of Chemical Physics and Biophysics NICPB, Tallinn, Estonia
⁴ Helsinki Institute of Physics, Helsinki, Finland
⁵ Department of Physics, University of Helsinki, Helsinki, Finland
⁶ MTA Wigner Research Center, RMKI, Budapest, Hungary
⁷ INFN Sezione di Bari, Bari, Italy
⁸ Dipartimento Interateneo di Fisica di Bari, Bari, Italy
⁹ INFN Sezione di Genova, Genoa, Italy
¹⁰ Università degli Studi di Genova, Genoa, Italy
¹¹ INFN Sezione di Pisa, Pisa, Italy
¹² Università degli Studi di Siena and Gruppo Collegato INFN di Siena, Siena, Italy
¹³ CERN, Geneva, Switzerland
¹⁴ Department of Physics, Case Western Reserve University, Cleveland, OH, USA
¹⁵ AGH University of Science and Technology, Kraków, Poland
¹⁶ University of West Bohemia, Plzen̆, Czech Republic
¹⁷ INRNE-BAS, Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria
¹⁸ Ioffe Physical-Technical Institute of Russian Academy of Sciences, St. Petersburg, Russia
¹⁹ Warsaw University of Technology, Warsaw, Poland
²⁰ Institute of Nuclear Physics, Polish Academy of Science, Kraków, Poland
²¹ Department of Atomic Physics, Eötvös University, Budapest, Hungary
²² SLAC National Accelerator Laboratory, Stanford, CA, USA
²³ Department of Physics, Penn State University, University Park, PA, USA

^* e-mail: mirko.berretti@cern.ch

Received: 19 November 2014
Accepted: 2 March 2015
Published online: 17 March 2015

Abstract

The pseudorapidity density of charged particles dN $_{ ch }$ /d $\eta$ is measured by the TOTEM experiment in proton–proton collisions at $\sqrt{s} = 8$ TeV within the range $3.9<\eta <4.7$ and $-6.95<\eta <-6.9$ . Data were collected in a low intensity LHC run with collisions occurring at a distance of 11.25 m from the nominal interaction point. The data sample is expected to include 96–97 % of the inelastic proton–proton interactions. The measurement reported here considers charged particles with $$p_T>0$$ MeV/c, produced in inelastic interactions with at least one charged particle in $-7<\eta <-6$ or $3.7<\eta <4.8$ . The dN $_{ ch }$ /d $\eta$ has been found to decrease with $|\eta |$ , from 5.11 $\pm$ 0.73 at $\eta =3.95$ to 1.81 $\pm$ 0.56 at $\eta =-$ 6.925. Several Monte Carlo generators are compared to the data and are found to be within the systematic uncertainty of the measurement.