The inclusive differential cross sections for the production of $$\pi^{\pm}$$ and $$k^{-}$$ mesons, protons, and antiprotons with momenta between 6 and 50 GeV/c and nuclear fragments of mass number $$1\leq A\leq 10$$ in the momentum range between 20 and 220 GeV/c were measured in carbon–lead collisions at a beam kinetic energy of 19.6 GeV per nucleon ( $$\sqrt{S_{NN}}=6.3$$ GeV). A comparison with the respective cross sections for carbon–carbon interactions is performed, and the dependence on the target mass number ( $$A$$ ) is estimated. The present analysis shows that the observed particles originate predominantly from peripheral interactions.

Analytical solutions for amplitude and time measurements from digitized signals of the pseudo-Gaussian shape are considered. The least squares method (l.s.m.) is chosen as the algorithm to determine amplitude A and timestamp t0. For a profile with an uncorrelated sampling the l.s.m. is reduced to analytical formulas consistent with the experiment. This permits to estimate the desired number of points Ns on a profile. The obtained results for Ns are illustrated with qualitative estimates in accordance with the Nyquist–Shannon–Kotelnikov sampling theorem. The optimality of the electronic filters forming the waveform is analyzed in terms of the excess noise factor. An analytical solution is found for the autocorrelation function from stochastic noise sources. It permits to define non-diagonal weight matrix elements in the l.s.m. with formulation of requirements for neglecting sampling correlations.

The inclusive differential cross sections for forward production of nuclear fragments at an angle of 0∘ in CC collisions at beam energy 20.5 GeV/nucleon (SNN=6.3GeV) are presented. Measurements have been performed at the U-70 Accelerator Complex (Protvino) using a combined spectrometer on base of the beamline. Fragments selection was carried out by measuring of ionization in scintillation counters taking into account the data from threshold Cherenkov counters and hadron calorimeter. Fragment mass was determined through Cherenkov light emission angle measured in the spectrometer of ring imaging Cherenkov radiation. Data are given for fragments with charge 1≤Z≤6, atomic number 1≤A≤10 and A/Z<3.4 with momenta from 20 to 210 GeV/c. The measurements are compared with Fritiof model, statistical models and theoretical parameterizations. The discovered differences between theory and experiment are discussed.

The invariant cross sections for forward charged-hadron production at zero angle in carbon–carbon collisions at a beam kinetic energy of 19.6 GeV per nucleon were measured at the U-70 accelerator in an experiment performed with the aid of a combined spectrometer including beam line 22 and detectors of the modified FODS setup. The beam line rigidity was varied between 7 and 70 GeV/$$c$$. The results are compared with the predictions of the FTFP model and a self-similar solution for nucleus–nucleus collisions.

The results of the simulation of the spectrometer acceptance for forward production of hadrons and nuclear fragments in nucleus−nucleus collisions at the U-70 accelerator complex are presented. The spectrometer is composed of beamline 22 of the U-70 accelerator and the detectors of the upgraded FODS facility with location of nuclear targets at the beamline head. The calculations have been performed in the virtual Monte Carlo environment of the ROOT package from the GEANT4 toolkit (version 4.10.02.p02). The passage of secondary hadrons (charged π and K mesons, protons, and antiprotons), secondary light nuclei (D, T), and heavier isotopes (He, Li, Be, B, and C) have been studied. In addition to the acceptance for each type of particles and nuclei, the coefficients of their escape from an ensemble due to decays and interactions during their passage through the spectrometer have been calculated.

The issues of determining the momentum of charged particles at the focusing double-arm spectrometer (FODS) are discussed. The coordinate detectors are located at the exit from the analyzing magnet, while a profilometer of the center of gravity of the beam at the target during an accelerator cycle is at its entrance. ANSIS finite-element analysis software is used to obtain a regular grid of magnetic field vector values measured by the Hall sensor in a part of the magnet. The charged-particle momentum is determined based on the algorithm of decision tables with a polynomial approximation. Tables are produced by the Monte Carlo method by reconstructing the motion of a particle with a prescribed momentum in the magnetic field. The accuracies in determining the particle momentum and the particle production angles while accounting for the contributions from multiple scattering, measurement errors, and approximation uncertainties are presented. The distribution of the reconstructed trajectories in the target and the momentum spectrum of particles are shown.

A procedure for finding the trajectories of charged particles on the FODS (focusing double-arm spectrometer) is described, which includes channel calibration (r(t)-dependence) of drift detectors for calculating the coordinates of particles and reconstruction of tracks. The organization of time measurements and construction of a least-squares functional on their basis is considered. The criteria for selecting candidates for the tracks are discussed. A procedure has been developed for obtaining geodesic corrections for drift chambers and tubes at the analysis of physical events. Accuracies of measuring the coordinates in drift chambers of 600 μm and chambers on drift tubes of 500 μm were obtained. The distribution of particle trajectories in the target is given.

The zero angle production of light nuclei has been studied in CC-interactions at beam energy 20.5 GeV/n on accelerator U-70. The measurements were performed with employing of the beamline no. 22 as spectrometer of secondary particles with verying its rigidity from 10 to 70 GeV/c. We observed secondary protons and deuterons with momenta above kinematic limit of NN-interactions. The measured dependence of forward yields on momentum are compared with the model predictions in the framework of Geant4. The models more or less correctly give positions of maxima of the distributions and their general qualitative dependence on the momentum. But in the quantitative predictions of the yields there are significant differences with the experiment which grow with increase of atomic mass number A.

Relative yields of high-x F charged hadrons (π ±, К±, р, \(\overline p \), and d) in proton–nucleus interactions at incident-proton momenta of 25 and 50 GeV/c were measured at an angle of 0° in the momentum range between 15 and 40 GeV/c. An upper limit on the forward production of two protons in proton–nucleus interactions at 50 GeV/c was estimated. The properties of a carbon beam with an energy of 25 GeV per nucleon and fragment yields in its interaction with nuclear targets were measured within a short exposure.

The results of an analysis of data from the SERP-Е-184 experiment devoted to studying mechanisms of the production of charmed particles in proton–nucleus interactions at 70 GeV and their decays are presented. The data in question were obtained upon irradiating the SVD-2 active target consisting of carbon, silicon, and lead plates with a beam of 70-GeV protons. A detailed simulation on the basis of the FRITIOF7.02 and GEANT3.21 code packages made it possible to optimize event-selection criteria and to calculate the detection efficiency for Λ c + baryons. After selecting a signal from the threebody decay of a Λ c + baryon, the inclusive cross section for its production at near-threshold energies, its lifetime, and the parameter of the A dependence of the cross section were found. The Λ c + -baryon yields are tabulated along with data from other experiments and theoretical predictions.

Amplitude and time spectra of a drift tube (DT) were investigated using cosmic radiation at different voltages applied to it and different compositions of an Ar + CO 2 gas mixture. The dependence of the drift time on the CO 2 concentration was studied. The mode of DT response mainly to the first cluster was selected. The working point for the high voltage applied to the tube was determined. It was shown that the spatial resolution of a DT for the FODS tracking system for cosmic events is ~0.5 mm.

Beamline 22 for selecting and transporting light high-energy nuclei at the U-70 accelerator (Protvino) has been simulated. The calculations have been performed in the virtual Monte Carlo environment of the ROOT package as a part of the GEANT4 program. The passage both of carbon beam nuclei and of secondary nuclear fragments and particles from scattering of carbon nuclei and protons with a momentum of 24 AGeV/c (A is the mass number) from a carbon target installed at the head of beamline 22 is studied. The cross sections of nuclear fragment production are estimated. The yields of secondary nuclei and particles at the end of beamline 22 per one accelerator cycle are calculated for the magnetic rigidity of the beamline ranging from 6 to 70 GeV/c. The contribution of background particles to the process including interaction of the beam flucton is estimated at the end of beamline 22.

The π 0, η, K 0, ω, and f 2(1270) masses were measured at the HYPERON-Msetup in meson-nucleus interactions at a momentum of 7 GeV/c by using six nuclear targets: Be, C, Al, Cu, Sn, and Pb. The experiment in question proved to be insensitive to the expected effects of a modification to the omega-meson mass in nuclear matter. As for the f 2(1270) meson, its mass and width values averaged over all experimental data, \(m_{f_2 }\) = 1275.8 ± 1.0(stat.) ± 0.4(syst.) MeV/c 2 and \(\Gamma _{f_2 }\) = 190.3 ± 1.9(stat.) ± 1.8(syst.) MeV/c 2, agree well with the world-average values. At the same time, our experimental data do not rule out the possible effect of an in-medium modification to the f 2(1270)-meson mass for heavy nuclei at a level better than 0.4%.

A method for correcting the nonlinearity of the electromagnetic calorimeter response is described. This method is based on minimizing the deviation of the measured mass of a neutral π0 meson decaying into two photons, depending on their energy. This method has been developed for the LGD2 electromagnetic calorimeter and used in the Hyperon-M experiment at the U-70 accelerator of the Institute for High Energy Physics. The proposed correction technique has made it possible to substantially reduce variations of the reconstructed π0 and η meson masses in accordance with their minimum energies.

This paper presents the analysis of procedures dedicated for time and amplitude reconstruction from sampling measurements of the ALICE electromagnetic spectrometer PHOS signal profile. The proposed approach is based on the least squares method to fit the profile measured in discrete number of points to the known impulse response function of electronic filter. Assuming semi-Gaussian shape of this function one can reduce the problem of simultaneous determination of signal time mark t0 and amplitude A to the solution of algebraic equation of the nth power, where n is the order of used electronic filter. The proper analytical formulae to define parameters A and t0 as well as their uncertainties σA and σt are proposed. This approach allows one to reduced substantially the processing time for effective estimation of A and t0 with simplification of the used software. The application of obtained formulae to the analysis of beam test data from the prototype of electromagnetic spectrometer PHOS equipped with the ALTRO electronics are considered together with corresponding Monte-Carlo simulation.

A structure of the multicomputer data acquisition complex for the Hyperon-M experiment at the U-70 accelerator (Protvino, Russia) is described. This complex has been designed to collect and merge data from several particle detectors, the electronic systems of which are made either to the MISS or SUMMA standard. The MISS system is autonomously operated under control of a special ЛЭ-74 controller that collects information in its internal buffer storage during a beam spill. The data acquired are combined with the information from the SUMMA electronics and are copied to an external storage device (a hard disk of a computer) in intervals between spills. On the contrary, software control is needed for the SUMMA electronics to read data on each event. Software-and hardware-based methods are used to provide joint operation of the electronic systems made to diverse standards and guarantee that the streams of incoming data are correctly merged. The problems of net interactions between different parts of the multicomputer system and monitoring of this system are analyzed.

A large-scale prototype of the PHOS electromagnetic spectrometer, which is part of the ALICE detector, has been built and tested. This prototype has 256 detector channels and is operated at −25°C. Each detector channel is a lead-tungstate crystal coupled to an Avalanche Photo-Diode with a low-noise preamplifier. The prototype includes a 16×16 crystal matrix, photo-detectors, analog and digital electronics, a thermo-stabilized cooling system, a light-emitting diode monitoring system, and a charged-particle detector acting as veto counter. Results of measurements using electron and hadron beams of the CERN PS and SPS accelerators are discussed, and the performance of the prototype is evaluated.

The possibility of colliding heavy nuclei with high luminosity at the Large Hadron Collider, expected to start operating in 2007 at CERN, offers a unique opportunity to investigate the behaviour of strongly interacting matter under extreme conditions of compression and heating. This will allow unprecedented tests of our understanding of equilibration processes and equilibrium states in Quantum Chromo-Dynamics (QCD), the fundamental theory of strong interactions. In particular, equilibrium QCD predicts that a phase transition to a plasma of deconfined partons, (the Quark–Gluon Plasma, or QGP), occurs at a critical energy density which is within experimental reach. Measurements at the LHC will probe extensively the properties of the bulk partonic matter produced in nucleus–nucleus collisions. The ALICE experiment—presently under construction—is the only LHC experiment designed specifically for the study of nucleus–nucleus collisions.

A neural network method is developed to separate direct photons from neutral pions in the PHOS spectrometer of the ALICE experiment at the LHC collider. The neural net has been taught to distinguish different classes of events by analyzing the energy profile tensor of a cluster in its eigenvector coordinate system. The Monte-Carlo simulation shows that this method diminishes the probability of π0-meson misidentification as a photon by an order compared with the direct photon detection efficiency in the energy range up to 120GeV.