The polarization of Lambda0, AntiLambda0, Sigma+ and Xi- inclusively produced in Sigma- induced interactions at 330 GeV has been measured in the experiment WA89 at CERN. This is the first measurement of polarization of baryons produced by a hyperon beam. No polarization of AntiLambda is observed, as was also the case in proton beam data. At transverse momenta of about 1GeV/c Lambda0 and Sigma+ show little polarization, significantly lower than in the proton beam data, while Xi- have a polarization comparable to the polarization of Lambda0 produced in proton beams.
Target Consisted of a copper and a carbon block arranged side by side.
Target Consisted of a copper and a carbon block arranged side by side.
Target Consisted of a copper and a carbon block arranged side by side.
Inelastic interactions of nuclei accelerated to a momentum of 4.5 GeV/$c$ per projectile nucleon with photoemulsion nuclei have been investigated. The main features of these interactions - mean ranges of $^6$Li nuclei, mean multiplicities of secondaries, the isotopic composition of fragments, fragmentation channels, and the mean transverse momenta of projectile fragments - have been measured. The probability of the charge-exchange reaction featuring lithium nuclei has been determined. The results obtained for the $^6$Li nucleus have been compared with data for other nuclei. The observed features of $^6$Li interactions with other nuclei indicate that the $^6$Li structure in the form of the loosely bound system consisting of an $\alpha$-particle and a deuteron cluster clearly manifests itself in these interactions. Events resulting in the coherent dissociation of $^6$Li nuclei into $^4$He+$d$, $^3$He+$t$, and $t+d+p$ and involving low-lying excitations of $^6$Li have been observed.
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Inclusive cross sections for Ξ- hyperon production in high-energy Σ-, π- and neutron induced interactions were measured by the experiment WA89 at CERN. Secondary Σ- and π- beams with average momenta of 345 GeV/c and a neutron beam of 260 GeV/c were produced by primary protons of 450 GeV/c from the CERN SPS. The influence of the target mass on the Ξ- cross section is explored by comparing reactions on copper and carbon nuclei. Both single and double differential cross sections are presented as a function of the transverse momentum and the Feynman variable xF. A strong leading effect for Σ- produced by Σ- is observed.
We report the first observation of the Xi- pi+ decay mode of the Xi0(1690), confirming the existence of this resonance. The Xi0(1690) were produced by Sigma- of 345 Gev/c mean momentum in copper and carbon targets. The mass and width are close to those observed earlier for the Xi-(1690) in the Lambda K- decay channel. The product of inclusive production cross section and branching ratio is given relative to that of the Xi0(1530).
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NUCLEUS IS NUCLEAR PHOTOEMULSION. EVENT WITH A TOTAL CHARGE OF ALL SPECTATOR FRAGMENTS OF A PROJECTILE = 0.
NUCLEUS IS NUCLEAR PHOTOEMULSION. EVENT WITH A TOTAL CHARGET OF ALL SPECTATOR FRAGMENTS OF A PROJECTILE = 1.
NUCLEUS IS NUCLEAR PHOTOEMULSION. EVENT WITH A TOTAL CHARGET OF ALL SPECTATOR FRAGMENTS OF A PROJECTILE = 0.
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Charge distributions of projectile fragments produced in the interactions of 22Ne beams with emulsion at 4.1A GeV/c have been studied. Correlations between projectile and target fragments and among projectile fragments are presented. The change of charge yield distribution with the violence of the collision has been shown. The present analysis contradicts theoretical calculations describing the inclusive charge yield distribution of fragments by a single process.
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The fragmentation topology of28Si at 3.7A GeV and 14.6A GeV and32S at 200A GeV in reactions with emulsion nuclei is presented. The fragmentation cross sections are very similar at all three energies. A statistical percolation model can qualitatively describe the data forZ≥ 6. The He production is underestimated and the 3 ≤Z ≤ 5 fragments overestimated by this model.
JINR.
BNL-815.
CERN-EMU-001.
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