We have measured a complete isotope distribution of projectile-like nuclear-charge pickup products, formed by bombarding a Al17 target with 790A MeV Xe129 ions. The shape of the cross-section distribution indicates a dominant influence of evaporation processes during the formation of the final cesium fragments observed, thus masking to a large extent the primary processes involved in the charge exchange. We can show, however, that an intranuclear-cascade-plus-evaporation calculation can reproduce the observed yields, and that the effect of Δ-formation during the first stage of the reaction is visible even in the inclusive cross sections. The same model can explain the strong increase in total charge-pickup cross sections with increasing projectile mass noted previously by other authors. It is therefore not necessary to invoke coherent processes to explain this increase as has been suggested previously.
No description provided.
The total cross section for γp→ηp near threshold has been measured using the PHOENICS tagging system at the ELSA electron facility of the Physikalisches Institut der Universität Bonn. The photons are created by bremsstrahlung, and are tagged by measuring the momentum of each electron after the photon has been emitted. The recoil proton from γp→ηp is detected by the AMADEUS counter setup in coincidence with the tagging system. Data were taken with AMADEUS at 3.3° in the laboratory, where the large Jacobian increases our event rate so that we obtain the cross section from threshold (Eγ=707.2 MeV) to Eγ≃720 MeV with adequate statistics. The γp→ηp events are identified by kinematics, dE/dx, and timing information. We find that in our energy region the production cross section is consistent with S-wave production.
No description provided.
We have investigated the fragmentation of 3.65 GeV/nucleon O16, Mg24, and S32 projectiles on C, Al, Cu, Ag, and Pb targets using solid state nuclear track detectors. Track counting was performed by an automatic measuring system. Total charge changing and the partial cross sections for the production of fragments with charges 9≤Z≤15 for S32 projectiles and of charge 6≤Z≤11 for Mg24 were determined. Comparison with theoretical models and other experimental data is made.
No description provided.
Pion-induced double charge exchange (π+,π−) on Se76,78,80,82, leading to the double isobaric analog states (DIAS) and the ground states of Kr76,78,80,82, has been studied at a laboratory angle of 50 and incident pion kinetic energy of 293.2 MeV. Cross sections for these transitions have been extracted, and those for the DIAS are compared to two simple models of pion double charge exchange.
No description provided.
The values of the pion nucleon (πN) σ term, as determined, on the one hand, from experimental pion nucleon scattering by means of dispersion relations and, on the other hand, from baryon masses by means of chiral perturbation theory, differ by 10 to 15 MeV. The origin of this discrepancy is not yet understood. If the difference between the two values is attributed to the scalar current of strange sea quark pairs within the proton, the contribution to the proton mass would be of the order of 120 MeV. The discrepancy may hint at either theoretical deficiencies or an inadequate πN database. In order to provide reliable experimental data we have measured angular distributions of elastic pion proton scattering at pion energies Tπ=32.2 and 44.6 MeV using the magnet spectrometer LEPS located at the Paul-Scherrer-Institute (PSI) in Villigen, Switzerland. From the data covering the region of the Coulomb nuclear interference, the real parts of the isospin-even forward scattering amplitude ReD+(t=0), have been determined as a function of energy. The results have been compared with the predictions of the Karlsruhe-Helsinki phase shift analysis KH80, revealing discrepancies most pronounced for the π+p data. The experimentally determined values for ReD+(t=0), however, support the KH80 prediction (which is based on πN data available in 1979).
Statistical and systematic errors are addet in quadrature.
Statistical and systematic errors are addet in quadrature.
Strange baryon and in particular multi-strange baryon production is suggested to be a useful probe in the search for quark gluon plasma formation in heavy ion collisions. We have measured the (Ω − + Ω + ) (Ξ − + Ξ + ) production ratio to be 0.8±0.4 at central rapidity and ϱ T > 1.6 GeV/c.
No description provided.
The shower particles multiplicity distribution produced in 60A GeV16O-Em collisions is studied in the framework of an extended Glauber model in which terms higher than the first (optical limit) in the phase shift expansion are considered. These are the so-called eclipse correction terms. The calculated distribution shows satisfactory agreement with the present experimental data.
TARGET NUCLEUS IS NUCLEI OF FUJI EMULSION.
A comparative study is made for12C-Em and16O-Em reactions, according to the soft-sphere model using measured mean free path and hence cross-sections together with other collected data. The fragmentation of projectile intoZ-fragments was studied in all interactions of16O-emulsion. The interactions depending on the impact parameter (which is characteristic of the target component) are investigated.
VALUES OF SIG WERE ESTIMATED USING FOLLOWING EQUATION: SIG=1/NL, WHERE N IS EFFECTIVE CONCENTRATION OF NUCLEI IN AN EMULSION OBTAINED 3.78*10**22 ATOMS/CM**3, AND L IS MEAN FREE PATH: 14.43 +-0.33 CM FOR C12 AND 12.8 +-0.33 CM FOR O16.
We present the basic characteristics of singly, doubly and heavily charged fragments of the incident nucleus in inelastic interactions of relativistic24Mg nuclei in nuclear emulsion. The relationship between the charge of the incident projectile nuclei and those of the projectile fragments is studied. The result reflects the importance of the charge of the incident projectiles and consequently the electromagnetic interactions in the fragmentation processes.
No description provided.
No description provided.
No description provided.
Experimental data on multiplicities and correlations of charged particles of different types produced in collisions of 4.5 A GeV/c carbon-12 with emulsion are reported and discussed. The data are compared with the results of other experiments on nucleus–nucleus and hadron–nucleus collisions. It is found that the particle production mechanism in nucleus–nucleus collisions is almost the same as in hadron–nucleus collisions. It is also observed that the shower particles' multiplicity distributions obey a KNO type scaling law, which supports the aforementioned result.
No description provided.
No description provided.
No description provided.
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