V.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.

Studying of hypernuclei with nuclotron beams

A spectrometer is created to study relativistic hypernuclei produced with beams of accelerated nuclei from the Nuclotron facility (Dubna, JINR). Test runs have been carried out and the conclusion is drawn that the properties of the facility meet the requirements of the task of searching for unknown and studying poorly known neutron-rich hypernuclei.

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.

Relativistic hypernuclei at Dubna

At the Laboratory of High Energies (JINR, Dubna) a unique approach was elaborated with hypernuclei produced by the excitation of the beam nuclei and their decays observed at a distance of tens of cm behind the production target. While the very first experiments were carried out in the Synchrophasotron beams, more extensive hypernuclei research programme is planned for the Nuclotron accelerator and the new spectrometer created by the authors. At the time of the conference the first test run in the Nuclotron beam was in progress. Investigation of hydrogen hypernuclei isotopes is in the first line of the experimental research plans. Namely, lifetimes and production cross sections of Λ 4 H and Λ 3 H will be measured. Search for Λ 6 H is also among the tasks.