Czech.J.Phys.B

Topological cross sections and characteristics of charged particle multiplicity distributions for¯nn andnn interactions and¯nn annihilations at 6·1 GeV/c are presented. KNO-distributions for¯nn andnn interactions are very similar. Characteristics for¯nn and¯pp annihilations are identical at equal energies.

Nucl.Instrum.Meth.A

Z.Phys.C

The polarization parameter in the reactions π−p→ηn and π−p→η′n at 40 GeV/c with −t ranging from 0 to 2.6 (GeV/c)2 and 1.0 (GeV/c)2, respectively, was measured in experiments using a propanediol polarized target. Only gamma particles from the neutral meson decay were detected. The polarization parameter of the first reaction turns out to be negative in a widet interval (0.05<−t<1.6 (GeV/c)2) and probably changes its sign at larger values oft. The average value of the polarization parameter of the second reaction is equal to −17±8)% in the region 0.05<−t<0.5 (GeV/c)2.

Nucl.Phys.A

By means of a streamer chamber exposed to the LEAR antiproton beams, the total reaction cross sections, the charged-prong multiplicity distributions and lower limits for the production of negative pions and K s 0 in the p̄-Ne interaction were measured at 19.6, 48.7 and 179.6 MeV. Annihilation was found to be dominant over all other non-elastic p̄-Ne processes. An analysis of Ne and other nuclei data in the frame of the Glauber theory allowed us to determine the ratio between the p̄-n and the p̄-p cross sections. An analysis in the light of INC model predictions allowed us to show up events which can be interpreted as annihilations having occurred deeply inside the nuclei.

Phys.Lett.B

A new value of the upper limit for the branching ratio of the decay of K 0 S into e + e − has been experimentally obtained using a lead glass detector. The value is BR (K 0 S → e + e − ) < 1.1 × 10 −4 (90% CL).

EPL

The charged-prong multiplicity distribution of (, Ag/Br) annihilation events has been measured in photographic emulsion at incoming momenta of 500, 400, 300 MeV/c and at rest. In the light of INC model predictions, the results show that the low-multiplicity events are produced mainly by nuclear surface annihilations and the higher multiplicity events can be interpreted as annihilations occurred in deep nuclear matter.

Phys. Lett. B

The antiproton-helium reaction cross section has been measured at 19.6 and 48.7 MeV with a streamer chamber in a magnetic field. Charged prongs and negative pion multiplicities and cross sections for the production of 3 He are given. A comparison with p 2 H is performed. he previously obtained 179.6 MeV results are also taken into account.

Czech. J. Phys. B

Data obtained in the study of the antiproton interaction on4He, Ne and photographic emulsion nuclei are reported. Charged prong multiplicities, branching ratios and reaction cross-section values are given. Some features of¯p annihilation deep inside the nuclear matter are described. Cosmological restrictions deduced from3He production in¯p4He reactions are discussed.

J.Phys.Colloq.

Abstract The results on measuring the asymmetries in the reactions π-p → π°n, π-p → ηn, π-p → η'(958)n, π-p → f (1270)n at 40 GeV/c are presented. Some new phenomena have been discovered in the asymmetry behaviour in these reactions.

Phys. Rev. Lett.

We report the results of a Fermilab Tevatron experiment using a Σ− beam with a measured polarization of 0.22 ± 0.04. We find the electron asymmetry in Σ− beta decay to be αe=−0.53±0.14 on the basis of a sample of 25 000 events, in agreement with the Cabibbo model and in contradiction with previous experiments. The corresponding value for the ratio of axial-vector to vector form factors is g1f1=−0.29±0.07.

Theor. Math. Phys.

Nucl. Phys. A

Helium break-up reactions have been studied in 4 He-proton interactions at 8.6 GeV/ c 4 He momentum in the hydrogen bubble chamber. Total and differential cross sections for different reaction channels without pion production have been measured. The results have been compared with multiple scattering model predictions.

Sov.Phys.J.

Wave functions of the Klein-Gordon and Dirac equations are determined in the quasiclassical approximation. These wave functions allow one to obtain results of the axial approximation as a particular case and to take into account in the emission problem quantum corrections related to both the dynamic of electron motion and quantum recoil during phonon emission.

Yad.Fiz.

The mechanism of the reaction 3 He + p → p + p + d is studied by making use of the ITEP 80 cm liquid-hydrogen bubble chamber exposed to a beam of 5 GeV/ c 3 He nuclei. The reaction cross section is equal to 20.6 ± 0.3 mb. The phase-space regions associated with quasifree scattering (QFS) and final-state interactions (FSI) are selected. Angular, mass and momentum distributions of the reaction products are obtained in the entire kinematically allowed range. The experimental data in the QFS region are compared with theoretical calculations based on the simplest pole-diagram approximation. The 3 He and deuteron wave functions (WF) correspond to the realistic RSC potential. The D-wave components of these WF are taken into account. The absolute value of the cross section and shape of the distributions are described as a whole reasonably well within the frame of the model considered in the kinematical region where FSI may be neglected. But at large spectator momenta there is an essential disagreement. The possible reasons for this are discussed.

Z. Phys. C

We present results obtained in π−A (A=C, Cu, Pb) — collisions at 38 GeV/c. A single particle trigger selects events with one charged particle in the central region and large transverse momentum. The effect of this trigger on the multiplicities of all charged particles and of protons is shown.

Nucl. Instrum. Meth. A

Electron track holograms were registered in a 10 atm helium-methane ( 3 1 ) self-shunted streamer chamber. From the Gabor holograms tracks were reconstructed: a streamer density of (14 ± 1) str/cm and streamer images of about 150 μm in diameter were obtained. The density and diameter values remain constant for delay times of the laser pulse with respect to the high voltage pulse within the range of 200 to 9000 ns.