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

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2015-03, Vol.75 (3)
• Main Authors: Antchev, G., Aspell, P., Atanassov, I., Avati, V., Baechler, J., Berardi, V., Berretti, M., Bossini, E., Bottigli, U., Bozzo, M., Brücken, E., Buzzo, A., Cafagna, F. S., Catanesi, M. G., Covault, C., Csanád, M., Csörgő, T., Deile, M., Doubek, M., Eggert, K., Eremin, V., Ferro, F., Fiergolski, A., Garcia, F., Georgiev, V., Giani, S., Grzanka, L., Hammerbauer, J., Heino, J., Hilden, T., Karev, A., Kašpar, J., Kopal, J., Kundrát, V., Lami, S., Latino, G., Lauhakangas, R., Leszko, T., Lippmaa, E., Lippmaa, J., Lokajíček, M. V., Losurdo, L., Lo Vetere, M., Lucas Rodríguez, F., Macrí, M., Mäki, T., Mercadante, A., Minafra, N., Minutoli, S., Nemes, F., Niewiadomski, H., Oliveri, E., Oljemark, F., Orava, R., Oriunno, M., Österberg, K., Palazzi, P., Peroutka, Z., Procházka, J., Quinto, M., Radermacher, E., Radicioni, E., Ravotti, F., Robutti, E., Ropelewski, L., Ruggiero, G., Saarikko, H., Scribano, A., Smajek, J., Snoeys, W., Sodzawiczny, T., Sziklai, J., Taylor, C., Turini, N., Vacek, V., Welti, J., Whitmore, J., Wyszkowski, P., Zielinski, K.
• Format: Article
• Language: English
• Subjects: Monte Carlo; Monte Carlo Generator; Monte Carlo Prediction; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Reconstructed Track; Systematic Uncertainty
• ISSN: 1434-6044; 1434-6052

The pseudorapidity density of charged particles dNch/dη is measured by the TOTEM experiment in proton–proton collisions at √s = 8 TeV within the range 3.9 < η < 4.7 and –6.95 < η < –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 pT > 0 MeV/c, produced in inelastic interactions with at least one charged particle in –7 < η < –6 or 3.7 < η < 4.8. The dNch/dη has been found to decrease with |η|, from 5.11 ± 0.73 at η = 3.95 to 1.81 ± 0.56 at η = –6.925. Several Monte Carlo generators are compared to the data and are found to be within the systematic uncertainty of the measurement.