Analysis of test beam data taken with a prototype of TPC with resistive Micromegas for the T2K Near Detector upgrade

In this paper we describe the performance of a prototype of the High Angle Time Projection Chambers (HA-TPCs) that are being produced for the Near Detector (ND280) upgrade of the T2K experiment. The two HA-TPCs of ND280 will be instrumented with eight Encapsulated Resistive Anode Micromegas (ERAM) on each endplate, thus constituting in total 32 ERAMs. This innovative technique allows the detection of the charge emitted by ionization electrons over several pads, improving the determination of the track position. The TPC prototype has been equipped with the first ERAM module produced for T2K and with the HA-TPC readout electronics chain and it has been exposed to the DESY Test Beam in order to measure spatial and dE/dx resolution. In this paper we characterize the performances of the ERAM and, for the first time, we compare them with a newly developed simulation of the detector response. Spatial resolution better than 800 ${\mu \rm m}$ and dE/dx resolution better than 10% are observed for all the incident angles and for all the drift distances of interest. All the main features of the data are correctly reproduced by the simulation and these performances fully fulfill the requirements for the HA-TPCs of T2K

Multiplicity and net-electric charge fluctuations in central Ar+Sc interactions at 13A, 19A, 30A, 40A, 75A, and 150A GeV ⁣/ ⁣cA\,\hbox {GeV}\!/\!c beam momenta measured by NA61/SHINE at the CERN SPS

This paper presents results on multiplicity fluctuations of positively and negatively charged hadrons as well as net-electric charge fluctuations measured in central Ar+Sc interactions at beam momenta 13A, 19A, 30A, 40A, 75A, and 150AGeV/c. The fluctuation analysis is one of the tools to search for the predicted critical point of strongly interacting matter. Results are corrected for the experimental biases and quantified using cumulant ratios. In most instances, multiplicity and net-charge distributions appear narrower than the corresponding Poisson or Skellam distributions. Cumulant ratios are compared with the Epos1.99 model predictions, which provide a qualitative description that aligns with observations for positively and negatively charged particles. The obtained results are also compared to earlier NA61/SHINE results from inelastic p+p interactions in the same analysis acceptance

Measurements of π+\pi^+, π−\pi^-, pp, pˉ\bar{p}, K+K^+ and K−K^- production in 120 GeV/cc p + C interactions

This paper presents multiplicity measurements of charged hadrons produced in 120 GeV/$c$ proton-carbon interactions. The measurements were made using data collected at the NA61/SHINE experiment during two different data-taking periods, with increased phase space coverage in the second configuration due to the addition of new subdetectors. Particle identification via $dE/dx$ was employed to obtain double-differential production multiplicities of $\pi^+$, $\pi^-$, $p$, $\bar{p}$, $K^+$ and $K^-$. These measurements are presented as a function of laboratory momentum in intervals of laboratory polar angle covering the range from 0 to 450 mrad. They provide crucial inputs for current and future long-baseline neutrino experiments, where they are used to estimate the initial neutrino flux

Measurements of π+^{+} , π−^{−} , p , pˉ\bar{p} , K+^{+} and K−^{−} production in 120 GeV / c p + C interactions

This paper presents multiplicity measurements of charged hadrons produced in 120  GeV/c proton-carbon interactions. The measurements were made using data collected at the NA61/SHINE experiment during two different data-taking periods, with increased phase space coverage in the second configuration due to the addition of new subdetectors. Particle identification via dE/dx was employed to obtain double-differential production multiplicities of π+, π−, p, ¯p, K+, and K−. These measurements are presented as a function of laboratory momentum in intervals of laboratory polar angle covering the range from 0 to 450 mrad. They provide crucial inputs for current and future long-baseline neutrino experiments, where they are used to estimate the initial neutrino flux

Measurements of π±\pi ^\pm, K±K^\pm, p and pˉ\bar{p} spectra in 40Ar+45Sc^{40}\hbox {Ar+}^{45}\hbox {Sc} collisions at 13A to 150A Ge V ⁣/ ⁣c\text{ Ge }\hspace{-1.00006pt}\text{ V }\!/\!c

The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of nuclei of varied sizes. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of $π^±, K^±, p$ and $\bar{p}$ producedin $^{40}$Ar+$^{45}$Sc collisions at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A GeV/c. The analysis uses the 10% most central collisions, where the observed forward energy defines centrality. The energy dependence of the $K^±/π^±$ ratios as well as of inverse slope parameters of the $K^±$ transverse mass distributions are placed in between those found in inelastic $p + p$ and central $Pb + Pb$ collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical or dynamical models

Measurement of hadron production in π–^{–}−C interactions at 158 and 350 GeV / c with NA61/SHINE at the CERN SPS

We present a measurement of the momentum spectra of π $^{±}$, K$^{±}$, p$^{±}$, Λ, $\overline{Λ}$, and K$^{0}$$_{S}$ produced in interactions of negatively charged pions with carbon nuclei at beam momenta of 158 and 350 GeV/c. The total production cross sections are measured as well. The data were collected with the large-acceptance spectrometer of the fixed target experiment NA61/SHINE at the CERN SPS. The obtained double-differential p−pT spectra provide a unique reference dataset with unprecedented precision and large phase-space coverage to tune models used for the simulation of particle production in extensive air showers in which pions are the most numerous projectiles

Two-pion femtoscopic correlations in Be+Be collisions at sNN=16.84\sqrt{s_{\text {NN}}} = 16.84 GeV measured by the NA61/SHINE at CERN

This paper reports measurements of two-pion femtoscopic correlations in Be+Be collisions at a beam momentum of 150A GeV/c (energy available in the center- of-mass system for nucleon pair $\sqrt{s_{\text {NN}}} = 16.84$ GeV) by the NA61/SHINE experiment at the CERN SPS accelerator. The obtained momentum space correlation functions can be well described by a Lévy distributed source model. The transverse mass dependence of the Lévy source parameters is presented, and their possible theoretical interpretations are discussed. The results show that the Lévy exponent α is approximately constant as a function of mT , and far from both the Gaussian case of α = 2 or the conjectured value at the critical end- point, α = 0.5. The radius scale parameter R shows a slight decrease in $m_T$ , which can be explained as a signature of transverse flow. Finally, an approximately constant trend of the intercept parameter λ as a function of $m_T$ was observed, similar to previous NA44 S + Pb results (obtained with a Gaussian approximation, but unlike RHIC results)

Measurements of K0^{0}S_{S}, Λ , and Λˉ\bar{Λ} production in 120 GeV / c p + C interactions

This paper presents multiplicity measurements of K0S, Λ, and ¯Λ produced in 120  GeV/c proton-carbon interactions. The measurements were made using data collected at the NA61/SHINE experiment during two different periods. Decays of these neutral hadrons impact the measured π+, π−, p and ¯p multiplicities in the 120  GeV/c proton-carbon reaction, which are crucial inputs for long-baseline neutrino experiment predictions of neutrino beam flux. The double-differential multiplicities presented here will be used to more precisely measure charged-hadron multiplicities in this reaction, and to reweight neutral hadron production in neutrino beam Monte Carlo simulations