[en] Results are presented of investigations of the specifications of a narrow-gap two-coordinate drift chamber with the 80% CF₄+20% i-C₄H₁₀ mixture, operating in a 10 kOe magnetic field. Ionization electron drift is investigated in a magnetic field, perpendicular to the chamber plane. The spatial resolution along the X coordinate is 220 mcm and does not depend on the magnetic field value. The chamber coordinate resolution along the Y coordinate is 150 mcm without the magnetic field and in its presence. 10 refs.; 10 figs

[en] An experimental study of the radiative decay π^- → e^- anti vγ is carried out in a secondary beam of negative π mesons with energy 17 GeV at the U-70 accelerator of the Institute of High-Energy Physics using the ISTRA setup of the Institute of Nuclear Research, Academy of Sciences of the USSR. The performance of the experiment in a high-energy beam permitted them to investigate the decay in a broad range of kinematic variables: E_γ > 21 MeV and E_e > 70 - 0.8 E_γ MeV. The ratio of the axial and vector form factors γ = 0.41 ± 0.23 is determined uniquely. Using a model-independent method, the authors found the value of the vector form factor |F_v| = 0.014 ± 0.009. The total probability of the π→ evγ decay in the indicated kinematic range is Λ(π^- → e^- anti vγ)/Λ (π^- → all) = (1.61 ± 0.23) x 10^-7. The contributions coming from the structural radiation and internal bremsstrahlung are investigated

[en] The main characteristics of cathode readout multiwire proportional chambers with 760 x 760 mm² active area are presented for particle loads up to 10³ part./mm²xs. The following chamber characteristics were obtained: efficiency, epsilon = 99%, space resolution, delta = 0.3 mm, rms of charge ratio Qsub(x)/Qsub(Y) for charges on the X- and Y-plane of one chamber deltasub(QX/QY) = 7%. A description is given of chamber design and operation, calibration and detector check-up procedures, and registered charged particle coordinate reconstruction methods. Calculated dependencies for the probability of obtaining the true multitrack event coordinate on the deltasub(QX/QY) value are presented. (orig.)

[en] An experiment studying the radiative pion decay, π^-→e^-anti νγ, has been performed with a secondary 17 GeV negative pion beam on the IHEP machine with the ISTRA facility of the Institute for Nuclear Research. The high energy beam has enabled us to investigate this decay in a wide range of kinematic variables: Eγ>21 MeV, Ee> 70-0.8Eγ MeV, which included events with θ_θγ>60deg. The axial-to-vector form factor ratio has been determined unambiguously: G=0.41±0.23. The vector form factor has been determined in a model independent way: vertical strokeFvertical stroke=0.014±0.009. The probability of the π^-→e^-νγ decay was found to be B.R.=(1.61±0.23)x10^-7 for the region under consideration. The contributions of the inner bremsstrahlung and of the structure dependent radiation were investigated. (orig.)

[en] An experiment studying the radiative pion decay, π^-→e^-anti νγ, has been performed with a secondary 17 GeV negative pion beam on the IHEP machine with the ISTRA facility of the Institute for Nuclear Research. The high energy beam has enabled us to investigate this decay in a wide range of kinematic variables: E_γ>21 MeV, E_e>70-0.8E_γ MeV, which included events with θ_eγ>60deg. The axial-to-vector form factor ratio has been determined unambiguously: γ=0.41±0.023. The vector form factor has been determined in a model independent way: vertical strokeF_vvertical stroke=0.014±0.009. The probability of the π^-→e^-anti νγ decay was found to be BR=(1.61±0.23)x10^-7 for the region under consideration. The contributions of the inner bremsstrahlung and of the structure dependent radiation were investigated. A possible interpretation is discussed. (orig.)

[en] The invariant mass spectrum of neutral final states produced in π^-p charge-exchange scattering at 40 GeV/c has been studied, searching for heavy particles decaying into 2γ. A peak is observed around 2.85 GeV/c². The cross section of the reaction π^-p→X(2.85)+n, times the branching ratio of the X→2γ decay, is measured to be sigma X BR approximately =2X10^-34cm². (Auth.)

[en] New results on a high statistics measurement of pion-nucleon charge exchange scattering at 40 GeV/c, extending in momentum transfer up to -t = 1.8 (GeV/c)², are reported and compared with an optical impact parameter model, together with previous data for the reaction π^-p→etan at the same energy. The imaginary part of the pole trajectory b₀(s) is determined from the slope of the tangent to the maxima of (-t)sup(1/2) dsigma/dt. The linear increase of Im b₀(s) with log s, which has been observed at low energies, continues up to 40 GeV/c. (Auth.)

[en] Measurements were made of the differential cross sections for the charge exchange of K^- mesons on protons at momenta of 25 and 40 GeV/c using a high-precision spectrometer with no magnetic field. In the range 5-40 GeV/c the reaction cross section follows a power-law dependence psub(K^-)sup(-1.52). In the small momentum transfer region (-t< approximately m²sub(π) a minimum is observed, similar to that discovered at lower energies. The differential cross sections at t=0 are considerably less than those predicted by the Regge-pole model. The parameters of the effective trajectory are determined. (Auth.)

[en] A high statistics measurement of the reaction π^-p → π⁰n has been performed at the Serpukhov accelerator for 15, 20, 25, 30 and 40 GeV/c incident pion momentum using the NICE set-up with its associated 648-channel hodoscope spectrometer for γ-ray detection. More than 3 million charge-exchange events have been recorded in total. It is found that the spin-flip and non-spin-flip amplitudes can be parametrized, for small mod(t) as exponentials with the same slopes to within a few per cent. Also the behaviour of the differential cross section for small and medium mod(t) agrees with the prediction of a geometrical s-channel model which describes binary reactions in terms of a complex pole b₀(s). The imaginary part of this universal pole, Im b₀(s), has been determined and found to be growing logarithmically with s. (Auth.)

[en] A description of the response of the NOMAD electromagnetic calorimeter to electrons and photons is discussed. In particular, the dependence of the two-dimensional shower shape on the angle and energy of the incident particle is parametrized by analytical functions. Some applications to the neutrino event reconstruction are also reported