A.T. Matyushin

Streamer chamber study of the cross sections and multiplicities in nucleus-nucleus interactions at the incident momentum of 4.5 GeV/c per nucleon

Abstract The experimental data obtained with the SKM-200 streamer chamber set-up are presented. The cross-section values and multiplicity distributions of negative secondaries in the inelastic 12 C interactions and in the central 12 C and 16 O collisions with pure nuclear targets (C, Ne, Si, Cu and Zr) are discussed. The results of this experiment and of the earlier ones concerning the 4 He-nucleus interactions at the same incident momentum of 4.5 GeV/ c are analyzed and compared with those of several other experiments and with the predictions of some theoretical models.

HBT measurement of the expansion velocity of pion production volume

Abstract Using a new method of data processing in the investigation of interference correlations of identical particles, a direct proof of nonstationarity of the π − production volume in central MgMg collisions at a beam momentum of p Iab = 4.4 GeV/c per nucleon was obtained. The velocity of a source of correlated π − meson pairs is introduced as a free parameter in the Lorentz transformed approximation formula of the interference peak. This velocity increases with increasing the velocity of a subset of π − mesons which are chosen for the interference analysis. The source velocity is the new experimentally measurable physical variable of interference analysis, apart from space-time sizes of the source.

Observation of the (e+e−)-decay modes of neutral vector mesons

Abstract The (e + e − ) decay rates of vector mesons have been measured using spark chambers and Cerenkov gamma-spectrometers.

New method for measuring the effective mass in the decays: x→γ+γ

Abstract A new method is described for effective mass measurement in the decays: x→ γ + γ ; x→e + +e − ; x→ π 0 + γ ; x→ π 0 + π 0 ; etc. with a two-channel system of jointly operating spark chambers and Cerenkov gamma-spectrometers. The system is calibrated for the decays: η 0 → γ + γ . The ΔM / M resolution has been obtained to be ±10%.

Observation of the ϕ → e+e− decay

Abstract Five events of the ϕ → e + e − decay have been identified using spark chambers and Cerenkov total absorption gamma spectrometers. The probability for these events to be simulated by the background is smaller than 0.1%. New data on the e + e − -decays of ϱ and ω-mesons have been obtained.