No abstract available

No abstract available

[en] The azimuthal asymmetry is measured for the emission of Z ≥ 2 particles from the interaction of ²²Ne, ²⁴Mg, ³²S, ⁵⁶Fe, ¹⁹⁷Au, and ²⁰⁷Pb nuclei with photoemulsion nuclei that is induced by semicentral collisions characterized by projectile energies in the range E_pr = 1.88-200 GeV per nucleon and by impact-parameter (b) values in the range 0.12 ≤ b/b_max ≤ 0.70. The results of these measurements are compared with the results of similar measurements for protons. It is found that, at a low energy of E_pr ∼ 2 GeV per nucleon, the ratio of the azimuthal-anisotropy coefficients v₂ for Z ≥ 2 particles and protons is 6 ± 2, but that, for energies in the region E_pr ≥ 4 GeV per nucleon, the coefficients in question agree with each other. This may suggest that, at low energies, Z ≥ 2 particles are predominantly formed at an early stage of the development of a collective flow. For E_pr ≥ 4 GeV per nucleon, these particles are presumably formed at the stage of nuclear-matter expansion. Other possible explanations for the results of the observation of an elliptic flux of Z ≥ 2 particles are discussed

[en] The emission of light nuclei (p, d, t) in the annihilation of K"− mesons stopped in a nuclear photoemulsion is measured. The deuteron-to-proton yield ratio is found to be d/p = 0.32 ± 0.05. The observed excess of evaporated protons is due to intranuclear-nucleon correlations

[en] The energy spectra of fast (10¹−10² keV) electrons accompanying π⁺ → μ⁺ decays of positively charged pions (π⁺) stopped in a nuclear emulsion are obtained. These spectra are compared with the analogous spectra obtained earlier for electrons accompanying the decay μ⁺ → е⁺. The comparison in question confirms qualitatively the hypothesis that, in either process, fast electrons appear via the mechanism based on Migdal’s shakeup effect.

[en] It is shown that, upon the stopping of a negatively charged kaon and its absorption by a nucleus, there arise particles whose appearance does not comply with thermodynamic evaporation theory. An identification of these particles by various methods makes it possible to evaluate the nearly identical yields of ³H and ³He nuclei. This result may serve as an indication that direct reactions induced by interaction with ⁴He are observed in K⁻-meson absorption in nuclei.

[en] It is shown that during the stopping and decaying of positively charged muon (μ⁺) in a nuclear emulsion, there arises with a probability of about 10⁻² electron with energies between 10 and 180 keV. The energy spectrum and angular distribution of these electrons are measured. A hypothesis on the possible mechanism behind the appearance of electrons corresponding to μ⁺ decay is put forth.

[en] The limits on the parameters of the ν_μ↔ν_τ oscillations are obtained in the E-564 hybrid experiment: Δm²≤4.5 eV² and sin²(2θ)≤6.0x10^-2(90% CL). A possibility of direct observation of τ-lepton decays in the nuclear emulsion vertex detector allowed the sensitivity of this experiment to the parameters of the oscillations to be increased. (orig.)

[en] About 0.85 × 10⁵ events involving stopped μ⁺ and muonium decay were observed in a nuclear photoemulsion with the aim of searches for a light dark photon (DPh) in the decay process DPh → e⁺e⁻. With a probability of about 10⁻⁵, no event of the decay μ⁺ → #0435#⁺ν_μν_е accompanied by an electron–positron pair was observed. In the interval of 1.1 MeV ≤ m_DPh ≤ 60 MeV, the mixing parameter ε² was estimated at about 10⁻⁵ to 10⁻⁴.

[en] We describe the (2x800 kg) emulsion target in the CHORUS hybrid detector set-up for the search of ν_μ→ν_τ oscillations, together with the CERN pouring and processing facilities (upgraded for this purpose), and the techniques employed to treat the emulsions used as the active target in the experiment