L.S. Okhrimenko

A Study of the production and lifetime of the lightest relativistic hypernuclei

Abstract All results on the production cross sections of the lightest hypernuclei and the lifetimes of the hydrogen hypernuclei obtained in Dubna streamer chamber experiments are presented.

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.

Measurement of the decay probability KL → 2πo

Abstract Using the 180-liter ITEP liquid xenon bubble chamber we have measured the branching ratio Γ (K L → 2 π o )/ Γ (K L → 3 π o ) to be (3.7 ± 0.8) × 10 −3 . We find | η oo | to be (2.02 ± 0.23) × 10 −3 .

Neutral decay modes of the η0 particle

Abstract Results of an investigation of the η0 meson decay modes η0 → γγ, η0 → π0γγ and η0 → 3π0 are presented. The branching ratios of the neutral decay modes have been evaluated.

Search for the neutral decays ωO → ηγ and ωO → πOπOγ

Abstract The decays of ω O → ηγ and ω O → π O π O γ are investigated by means of the effective mass method. Decay branching ratios of ω O → ηγ and ω O → π O π O γ are determined.

Investigation of the M(πoπo) effective mass spectrum

Abstract Investigation of the effective mass spectrum of the πo−πo system is carried out in the interval of mass values M(πoπo) ⩽ 1.3 GeV. A peak is observed at M (π o π o ) = 730 ± 15 MeV .

Pion production in nuclear charge exchange reactions A(t, 3He)

Abstract The charge exchange reaction (t, 3 He) on carbon and magnesium targets is investigated in experiments using a streamer chamber. The experimental pion longitudinal momentum spectrum is compared with the calculated one for events with a single secondary pion. From this comparison it follows that the contribution from quasi-free Δ − excitation in the target nucleus in a single pion channel is only 60–70%. The momentum of the pions in the remaining fraction of events is significantly higher than that of the pions produced in delta de-excitation. The contribution from several possible processes is analyzed. The data indicate a significant role of coherent pion production via N(1440) or/and N(1520) in the target nucleus while part of the pion spectrum can be explained by projectile excitation.

Study of the di-pion in the mass-value region M(πoπo) ⩽ 1.3 GeV

Abstract The results of investigation of the π o π o effective-mass spectrum in the mass-value region M ( π o π o ) ⩽ 1.3 GeV are presented. A peak is observed at M (π o π o ) = 730 MeV .