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The study of open charm meson production provides an efficient tool for the investigation of the properties of hot and dense matter formed in nucleus–nucleus collisions. The interpretation of the existing di-muon data from the CERN SPS suffers from a lack of knowledge on the mechanism and properties of the open charm particle production. Due to this, the heavy-ion programme of the NA61/SHINE experiment at the CERN SPS has been extended by precise measurements of charm hadrons with short lifetimes. A new Vertex Detector for measurements of the rare processes of open charm production in nucleus–nucleus collisions was designed to meet the challenges of track registration and high resolution in primary and secondary vertex reconstruction. A small-acceptance version of the vertex detector was installed in 2016 and tested with Pb + Pb collisions at 150 A GeV / c . It was also operating during the physics data taking on Xe + La and Pb + Pb collisions at 150 A GeV / c conducted in 2017 and 2018. This paper presents the detector design and construction, data calibration, event reconstruction, and analysis procedure.

We present experimental results on inclusive spectra and mean multiplicities of negatively charged pions produced in inelastic p+p interactions at incident projectile momenta of 20, 31, 40, 80 and 158 GeV/ c ( s = 6.3, 7.7, 8.8, 12.3 and 17.3 GeV, respectively). The measurements were performed using the large acceptance NA61/SHINE hadron spectrometer at the CERN super proton synchrotron. Two-dimensional spectra are determined in terms of rapidity and transverse momentum. Their properties such as the width of rapidity distributions and the inverse slope parameter of transverse mass spectra are extracted and their collision energy dependences are presented. The results on inelastic p+p interactions are compared with the corresponding data on central Pb+Pb collisions measured by the NA49 experiment at the CERN SPS. The results presented in this paper are part of the NA61/SHINE ion program devoted to the study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter. They are required for interpretation of results on nucleus–nucleus and proton–nucleus collisions.

A measurement of charged hadron pair correlations in two-dimensional [Formula omitted] space is presented. The analysis is based on total 30 million central Be + Be collisions observed in the NA61/SHINE detector at the CERN SPS for incident beam momenta of 19A, 30A, 40A, 75A, and 150A [Formula omitted]. Measurements were carried out for unlike-sign and like-sign charge hadron pairs independently. The [Formula omitted] correlation functions were compared with results from a similar analysis on p + p interactions at similar beam momenta per nucleon. General trends of the back-to-back correlations are similar in central Be + Be collisions and p + p interactions, but are suppressed in magnitude due to the increased combinatorial background. Predictions from the Epos and UrQMD models are compared to the measurements. Evolution of an enhancement around [Formula omitted] with incident energy is observed in central Be + Be collisions. It is not predicted by both models and almost non-existing in proton-proton collisions at the same momentum per nucleon.

The NA61/SHINE collaboration studies at the CERN Super Proton Synchrotron (SPS) the onset of deconfinement in hadronic matter by the measurement of particle production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range. This paper presents results on inclusive double-differential spectra and mean multiplicities of [Formula omitted] mesons produced in the 5% most central [Formula omitted]Be + [Formula omitted]Be collisions at beam momenta of 19A, 30A, 40A, 75A and 150 [Formula omitted] obtained by the so-called [Formula omitted] method which does not require any particle identification. The shape of the transverse mass spectra differs from the shapes measured in central Pb + Pb collisions and inelastic p+p interactions. The normalized width of the rapidity distribution decreases with increasing collision energy and is in between the results for inelastic nucleon-nucleon and central Pb + Pb collisions. The mean multiplicity of pions per wounded nucleon in central [Formula omitted]Be + [Formula omitted]Be collisions is close to that in central Pb + Pb collisions up to 75 [Formula omitted]. However, at the top SPS energy the result lies between those for nucleon-nucleon and Pb + Pb interactions. The results are discussed in the context of predictions for the onset of deconfinement at the CERN SPS collision energies.

The production of [Formula omitted] and [Formula omitted] hyperons in inelastic p+p interactions is studied in a fixed target experiment at a beam momentum of 158 [Formula omitted]. Double differential distributions in rapidity [Formula omitted] and transverse momentum [Formula omitted] are obtained from a sample of 33M inelastic events. They allow to extrapolate the spectra to full phase space and to determine the mean multiplicity of both [Formula omitted] and [Formula omitted]. The rapidity and transverse momentum spectra are compared to transport model predictions. The [Formula omitted] mean multiplicity in inelastic p+p interactions at 158 [Formula omitted] is used to quantify the strangeness enhancement in A+A collisions at the same centre-of-mass energy per nucleon pair.

The measurement of [Formula omitted] resonance production via its [Formula omitted] decay mode in inelastic p+p collisions at beam momentum 158 [Formula omitted] ( [Formula omitted] [Formula omitted]) is presented. The data were recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The template method was used to extract the [Formula omitted] signal and double-differential transverse momentum and rapidity spectra were obtained. The full phase-space mean multiplicity of [Formula omitted] mesons was found to be [Formula omitted]. The NA61/SHINEresults are compared with the Epos1.99 and Hadron Resonance Gas models as well as with world data from p+p and nucleus-nucleus collisions.

Results on [Formula omitted] meson production in inelastic [Formula omitted] collisions at CERN SPS energies are presented. They are derived from data collected by the NA61/SHINE fixed target experiment, by means of invariant mass spectra fits in the [Formula omitted] decay channel. They include the first ever measured double differential spectra of [Formula omitted] mesons as a function of rapidity [Formula omitted] and transverse momentum [Formula omitted] for proton beam momenta of [Formula omitted] and [Formula omitted], as well as single differential spectra of [Formula omitted] or [Formula omitted] for beam momentum of [Formula omitted]. The corresponding total [Formula omitted] yields per inelastic [Formula omitted] event are obtained. These results are compared with existing data on [Formula omitted] meson production in [Formula omitted] collisions. The comparison shows consistency but superior accuracy of the present measurements. The emission of [Formula omitted] mesons in [Formula omitted] reactions is confronted with that occurring in [Formula omitted] collisions, and the experimental results are compared with model predictions. It appears that none of the considered models can properly describe all the experimental observations.

Measurements of inclusive spectra and mean multiplicities of [Formula omitted], K [Formula omitted], p and [Formula omitted] produced in inelastic p + p interactions at incident projectile momenta of 20, 31, 40, 80 and 158 [Formula omitted] ( [Formula omitted] 6.3, 7.7, 8.8, 12.3 and 17.3 [Formula omitted], respectively) were performed at the CERN Super Proton Synchrotron using the large acceptance NA61/SHINE hadron spectrometer. Spectra are presented as function of rapidity and transverse momentum and are compared to predictions of current models. The measurements serve as the baseline in the NA61/SHINE study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter.

Measurements of particle emission from a replica of the T2K 90 cm-long carbon target were performed in the NA61/SHINE experiment at CERN SPS, using data collected during a high-statistics run in 2009. An efficient use of the long-target measurements for neutrino flux predictions in T2K requires dedicated reconstruction and analysis techniques. Fully-corrected differential yields of [Formula omitted]-mesons from the surface of the T2K replica target for incoming 31 GeV/c protons are presented. A possible strategy to implement these results into the T2K neutrino beam predictions is discussed and the propagation of the uncertainties of these results to the final neutrino flux is performed.