B.A. Kulakov

The pion radius

Abstract The pion radius has been measured by direct scattering of 50 GeV negative pions from stationary electrons in a hydrogen target. We find the square of the radius to be 〈 r π 2 〉 = (0.61 ± 0.15) fm 2 .

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.

A Measurement of the Electromagnetic Size of the Pion from Direct Elastic Pion Scattering Data at 50-GeV/c

Abstract We report the results of a pion-electron scattering experiment to measure the charge radius of the pion. The experiment was performed in a 50 GeV/c negative, unseparated beam at the IHEP accelerator, Serpukhov, and has been briefly reported in an earlier publication [1]. A magnetic spectrometer instrumented with wire spark chambers was used to record the incident pion trajectory and the angles and momenta of the scattered particles. Events are reconstructed by detailed trackfinding programs, and a set of kinematic and geometric cuts define the elastic sample. Electrons are identified both by kinematic criteria and pulse height information from total absorption lead glass Cerenkov counters. The final elastic sample consisted of 40 000 πe events in the region of four-momentum transfer squared 0.013 (GeV/c)2 ⩽ q2 ⩽ 0.036 (GeV/c)2. A full error matrix fit to the form factors of the pion gave the r.m.s. charge radius of the pion: 〈r π 2 〉 1 2 = (0.78 −0.10 +0.09 ) fm .

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 Mgue5f8Mg 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.

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.