Search

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.

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 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.

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.

Cross sections for the production of high-transverse-momentum charged hadrons in proton–nucleus interactions at the incident-proton energy of 50 GeV were measured with the aid of the FODS double-arm spectrometer. Single hadrons (charged pions and protons) emitted at a c.m. angle of about 90° and high-effective-mass pairs of hadrons flying apart at a c.m. angle of 180° were detected simultaneously. Results on the production of single hadrons are presented.

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 ( S N N = 6.3 GeV ) 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.

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 + CO2 gas mixture. The dependence of the drift time on the CO2 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.

A data acquisition system of the focusing double-arm spectrometer (FODS) setup is described. The information from each recording electronic module is read in response to each trigger by an ЛЭ-74 high-speed controller with a buffer memory and is transmitted by a PCI-7200 extension card to the computer memory at the end of the spill. All crates are read in parallel, ensuring a high speed of operation of the system (8000 events per spill for one spectrometer arm). The system is able to read data from different detectors (drift chambers, proportional chambers, calorimeters, Cherenkov radiation ring spectrometer, etc.), possesses a high flexibility, i.e., ensures readout of information for several types of triggers (inclusive, arm coincidence, two particles in one arm, etc.), and enables calibration of detectors in each spill. The software is based on the MIDAS project with an open initial code and allows one to control operation of all detectors during experiments.

A monitoring system comprising ionization and scintillation monitors has been developed to measure the intensity and to control the quality of the beam at the FODS spectrometer. The system has been designed for operation with beam intensities of 104–109 particles/s. The characteristics of the system components are presented.

Designs of the hadron calorimeters for the FODS setup and the procedure for their calibration are described. Results of investigations of their characteristics on electron and hadron beams are presented.

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.

The transverse single-spin asymmetry was measured for charged hadrons (π ±, K ±, p, $$\bar p$$ ) produced in proton-nucleus collisions. The measurements were performed at the FODS-2 spectrometer by using a polarized proton beam that was accelerated to an energy of 40 GeV at the accelerator of the Institute for High Energy Physics (IHEP, Protvino) and which was made to hit carbon and copper nuclear targets. The data in question were obtained in the range of c.m. angles between 73° and 94° near the central region (−0.01 < x F < 0.27, 0.7 < p T < 3.6 GeV/c). The single-spin asymmetry for π + and K + mesons is significant at high values of p T and moderately small positive values of x F. The analyzing power for other hadrons (π −, K −, p, $$\bar p$$ ) is compatible with zero in the p T range studied here. The dependence of the analyzing power on the mass number of the target nucleus is insignificant.

The transverse single-spin asymmetry was measured for charged hadrons ({pi}{sup {+-}}, K{sup {+-}}, p, p-bar) produced in proton-nucleus collisions. The measurements were performed with the aid of the FODS-2 spectrometer by using a 40-GeV polarized proton beam from the accelerator of the Institute for High Energy Physics (IHEP, Protvino) and carbon and copper nuclear targets. The data subjected to the analysis in the present study were obtained for c.m. angles in the range 95{sup o}-112{sup o} in the vicinity of the central region (-0.08 < x{sub F} < -0.06, 0.7 < p{sub T} < 3.4 GeV/c). The analyzing power is found to be only slightly dependent on the mass number of the target nucleus. The basic results obtained by measuring the single-spin asymmetry at three values of the particle-detection angle are discussed.

The transverse single-spin asymmetry for charged hadrons (π ±, K ±, p, $$\bar p$$ ) produced in proton-nucleus collisions was measured for c.m. production angles in the range 40°–79°. The measurements were performed with the FODS-2 setup by using a 40-GeV polarized proton beam originating from the accelerator of the Institute for High Energy Physics (Protvino) and hitting carbon and copper nuclear targets. The data in question were obtained in the polarized-proton-fragmentation region (0.0 < x F < 0.7, 0.6 < p T < 2.5 GeV/c). In agreement with data obtained at other energies, the single-spin asymmetry for π ± mesons is significant at high x F. For the first time, a sizable analyzing power, which changes sign at x F = 0.43, is observed for protons. The dependence of the analyzing power on the target-nucleus mass is insignificant.

A method for transportation of the calibration coefficients is described. This method is applicable in the case when the calorimeter is calibrated in one place and used elsewhere.

The end cap hadron calorimeter designed for the Compact Muon Solenoid (CMS) experiment is a sampling calorimeter with active elements based on scintillators read by wave length shifting fibers. We have fabricated 1368 optical elements containing 21096 scintillators. The production and the quality control of the optical elements are described.

An end cap hadron calorimeter, in which scintillators with wavelength-shifting fibers are used as the active elements, has been designed for the compact muon spectrometer (CMS) now under construction at CERN. A total of 1368 optical elements containing 21 096 scintillators have already been manufactured. The production and quality control procedures for these optical elements are described.

A setup has been developed for testing mass-produced scintillation counters. Its design and the quality control procedure for the scintillation counters of the hadron calorimeter are described.

The characteristics of the prototype of the endcap hadron calorimeter for the CMS facility have been measured. Using the relations between the measured calorimeter response to a radiation source, muons, and pions, it is possible to determine the energy scale of the data-acquisition electronics, which will be used in future experiments along with the calorimeter. The light yield in the calorimeter due to a minimum-ionizing particle was measured. The effect of various factors on the duration of the calorimeter signal is analyzed. The joint operation of the hadron and electromagnetic calorimeters was investigated. The possibility of adjusting the uncompensated system using the data from a scintillation counter inserted between the calorimeters is analyzed. It is shown that the presence of a structural material between the calorimeters will not lead to a noticeable degradation in the energy resolution of the hadron calorimeter.