[en] The method for calibrating the BARS large liquid-argon spectrometer constituting a part of the Traced neutrino complex of the U-70 accelerator is described. Registration of stopped muons in the spectrometer forms the basis of the method. The iteration way of determining the calibration coefficient by means of comparing the experimental data with the modeling data, obtained with an account of the readout noises and thresholds of the data acquisition system is proposed. The calibration method proposed may be applied also for other calorimeters with thin granulation and low registration threshold

[en] Paper dwells upon the procedure of the light-emitting diode calibration of a scintillation trigger detector of the D0 facility forward muon system making use of the Fermilab (the Fermi National Accelerator Laboratory) Tevatron accelerator, Batavia, USA. The deviation of the 4214 counters-averaged signal amplitudes within four year period was maximum 4% with the dispersion of the distribution of the mentioned deviations of all counters equal to 10%. Within the mentioned time period the signals remained time-stable ones within 0.23 ns limits with the dispersion of the deviation distribution equal to 0.52 ns. Paper describes as well the procedure to calibrate detector based on the measurement of the amplitude response of the counters as the muons resulting from the proton-antiproton collisions in the Tevatron accelerator pass through them. The absolute value variations of the amplitude responses within the four year period of the operation is maximum 3% - 9%

[en] The distributions of various characteristics of multiple interaction muon events in liquid-argon spectrometer BARS have been compared with Monte Carlo simulation for a spectrum of muons arising from π, K-decays in the atmosphere. Estimates of the slope of parent particle generation spectrum have been obtained

[en] The data accumulated in the long-term exposure of the large liquid argon spectrometer BARS, are analyzed in the horizontal cosmic rays flow. The events corresponding to the registration of the muon groups of the atmospheric origin are separated. The evaluations of the muon groups relative intensity at high zenith angles are obtained

[en] Experimental data accumulated due to long-term exposure of the BARS full-size liquid-argon spectrometer (Institute of High Energy Physics, Protvino) in a cosmic ray horizontal flow are analyzed to determine events corresponding to production of muon pairs by muons within a detector working volume. The observed number of such events is compared with calculations based on application of the available theoretical formulae for cross section of the mentioned process

[en] The charge asymmetry of the g, h, and k Dalitz plot parameters for K^±→π^±π⁰π⁰ decays has been measured with 35 GeV/c hadron beams at the 70 GeV IHEP accelerator. The g, h, and k values obtained appear to be identical for K^± decays within the errors quoted. In particular, the charge asymmetry A_g=(g⁺-g^-)/(g⁺+g^-) of the slope gis equal to (0.2±.9).10^-3. (orig.)

[en] The results are presented for the charge asymmetry of the Dalitz plot parameters g, h, and k measured for K^± → π^±π⁰π⁰ decays. The experiment has been carried out in the 35-GeV/c kaon beams at the IHEP accelerator. The g, h, and k parameters appear to be identical for K⁺ and K^- decays within the experimental uncertainty. In particular, a value of (0.2 ± 1.9) x 10^-3 is obtained for the charge asymmetry A_g = (g⁺ - g^-)/(g⁺ + g^-) of the Dalitz plot slope

[en] Experimental data accumulated over a long-term exposure of the big liquid-argon spectrometer BARS at the Institute for High Energy Physics (IHEP, Protvino) in a horizontal flux of cosmic rays are analyzed with the aim of selecting events that correspond to muon-pair production by muons in the sensitive volume of the detector. The results obtained in this way make it possible to perform, for the first time, a direct experimental test of various theoretical estimates of the total cross section for electromagnetic muon-pair production by high-energy muons

[en] A new type of scintillation detector for shower arrays is considered. The detector represents an octagonal scintillation assembly with total area 1 m² divided into sectors. Thickness of the plastic is 20 mm. The light is collected by wavelength shifter bars to the photomultiplier, which is located in the center of the detector. A solution to ensure the uniformity of light collection for any coordinate is proposed. Front-end electronics of the detector consists of the controller, the measuring part (QDC, TDC), the system of calibration and the HV converter. The data acquisition system is based on CAN-open standard. There is also a system of temperature stabilization that guarantees not more than 0.5 deg. deviation of the temperature of measuring part elements. Measuring electronics allows obtaining the dynamic range from 1 up to 10⁴ particles and 1 ns time digitization. The time resolution of the detector is about 3 ns.

[en] An amplitude analysis of an exclusive sample of 5765 events from the reaction π^- p → η(prime)π^- p at 18 GeV/c is described. The η(prime)π^- production is dominated by natural parity exchange and by three partial waves: those with J^PC = 1^-+, 2⁺⁺, and 4⁺⁺. A mass-dependent analysis of the partial-wave amplitudes indicates the production of the a₂(1320) meson as well as the a₄(2040) meson, observed for the first time decaying to η(prime)π^-. The dominant, exotic (non-q(bar q)) 1^-+ partial wave is shown to be resonant with a mass of 1.597 ± 0.010_-0.010^+0.045 GeV/c² and a width of 0.340 ± 0.040 ± 0.050 GeV/c². This exotic state, the π₁(1600), is produced with a t dependence which is different from that of the a₂(1320) meson, indicating differences between the production mechanisms for the two states