The absolute differential cross sections for ap elastic scattering and for the sum of elastic and quasielastic aa scattering have been measured at a momentum of 17.9 GeV/c in the four-momentum transfer region (0.01 < | t | < 0.2) GeV2/c2 with normalization errors less than 3%. Such measurements in the energy region of a few GeV have been performed for the first time. The measurements have been carried out using the alpha particle beam with the intensity of (1-5)x105 particles/s extracted from the synchrophasotron during 0.3-0.5s. The cryogen target filled with hydrogen (0.847+-0.001 g/cm2) and helium was used. The substance amount along the particle path constituted 0.11 g/cm2 in an unfilled target. The total cross sections, diffraction cone slope parameters and total elastic cross sections for ap and aa scattering have been obtained. The results are compared with the calculations carried out in the frames of the Glauber-Sitenko diffraction multiple scattering theory. The deviation of the calculated differential cross sections from the experimental ones is observed. In the region of the diffraction cone the deviation has a different sign for ap and aa scattering and amounts to 10-15%
The reactions K − d→ Σ − p, K − d→ Σ − (1385)p, K − d→ Λ (1405)n and K − d→ Λ (1520)n have been studied at K − momenta between 686 and 844 MeV/ c in an experiment with the 81 cm Saclay bubble chamber at CERN. About 630 000 pictures have been analyzed. Partial and differential cross sections are presented. A one-nucleon-exchange model is used to extract the kaon-nucleon-hyperon coupling constants from these results. For g( K N Σ(1197)), g( K N Σ(1385)) and g( K N Λ(1405)) we find values which are compatible with the SU(3) predictions. The coupling constant g( K N Λ(1520)) obtained by our method agrees with that determined from the partial decay width for Λ(1520)→ K N .
Differential cross sections and polarizations have been measured for the reaction π − p → K 0 Λ and π − p → K 0 Σ 0 at 3.9 GeV/ c π − momentum. Comparison of these data with those of the related reactions K − n → π − Λ and K − p → π − Σ + (at approximately the same c.m. energy) indicate that simple Regge-pole models involving only K ∗ (890) and K ∗ (1420) exchange are unable to describe all the features of the data. On the other hand, comparison of the π − p → K 0 Σ 0 data with that of π + p → K + Σ + shows that the data are consistent with absence of exotic strange-meson exchange.
A partial-wave analysis of the (3 π ) 0 system produced peripherally in the reaction K − p → π + π − π 0 Λ at 4.2 GeV/ c is presented. The observation of the weak Λ decay allows a determination of all the transversity production amplitudes except for two phases. The production of known resonances having decay modes other than 3 π is used to test the isobar model ansatz. Significant ω(783), φ(1020) and A 2 (1310) production is observed. The spin parity of the ω ∗ (1675) is established as 3 − . No evidence for production of other resonances, such as axial vector-mesons, is found.
We have measured the differential cross-section and the analyzing power (polarization) for p-He4 elastic scattering at incident kinetic energies of 0.56, 0.80, 1.03, 1.24, and 1.73 GeV. The experiment used a polarized proton beam incident on a liquid helium target and a single arm magnetic spectrometer to detect elastic scattering. Both the differential cross sections and the analyzing power show structure near −t=0.25 (GeV/c)2 which decreases in magnitude with increasing energy. Both multiple scattering and optical model interpretations of the data are discussed. NUCLEAR REACTIONS elastic scattering, p-He4; GeV energies; measured differential cross section; measured polarization; comparison with theory.
Measurements on large-angle photoproduction of π+ mesons from hydrogen have been made at the Stanford Linear Accelerator Center for photon energies between 5 and 15.5 GeV and u values from +0.05 to -1.8 (GeV/c)2. The measured cross section decreased with energy approximately as k−3, showing no shrinkage in this range of u values. Furthermore, it had a smooth u dependence with no sign of a dip at u≃−0.15 (GeV/c)2 as would be expected from nucleon exchange. π−Δ++ production was measured at 5 GeV and shows a rapid decrease with increasing |u|.
The total and topological 4Hep cross sections as well as the cross sections of the separate 4Hep interaction channels and the differential cross sections of the elastic 4Hep scattering were measured using the 2m hydrogen bubble chamber exposed to a separated beam of alpha-particles from the ITEP synchrotron at 5 GeV/c (the kinetic energy of the initial protons in the nuclear rest frame was 620 MeV). The data obtained have been compared with the results of the previous experiments and with the theoretical predictions based on the Glauber-Sitenko multiple-scattering theory.
The reaction γ d→d ππ , γ p→p ππ and γ n→n ππ were studied in the SLAC 82″ deuterium filled bubble chamber, exposed to a linearly polarized photon beam of 7.5 GeV. All three reactions are dominated by ϱ 0 production. The differential cross section has a slope of ∼6.5 GeV −2 for nucleon reactions and a slope of ∼27 GeV −2 for coherent deuteron reactions. The behaviour of the density matrix elements shows that ϱ production conserves s -channel c.m.s. helicity and is dominated by natural parity exchange.
The charge-exchange cross sections were measured for π − on Li, C, Al and Cu nuclei at momentum 48 GeV/ c . By comparing the data obtained for nuclei with those for hydrogen under the same conditions the effective numbers of protons are defined. The conclusion is made that η 0 mesons are absorbed in nuclei weaker then π 0 . The total cross section of η 0 interactions with the nucleon is determined to be σ tot ( η 0 N) = 15 ± 5 mb in agre ement with the quark model.
The results of a wire chamber spectrometer experiment studying K ∗ (890) production in the reaction K − p→ K − π + n at 13 GeV are presented. Strong forward structure is observed for | t |< m 2 π in the s -channel density matrix elements and differential cross section. These features are similar to those observed in π − p→ϱ 0 n data and are characteristics of π exchange. In contrast in the intermediate, | t | ∼ 0.2 GeV 2 , and large momentum transfer regions K ∗ (890) production is demonstrated by the natural parity ϱ−A 2 exchange contribution.
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