We present the inclusive and semi-inclusive production of protons, π+, π−, for the full range of kinematic variables, from 7850 inelastic interactions obtained in the 4.7 m liquid-hydrogen bubble chamber Mirabelle at the Serpukhov accelerator and with an incident proton beam of 69 GeV/c. We compare the data with those at other energies, and we give the results of different phenomenological fits.
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The reactions e + d → e ' + p S + p + π − and e + d → e ' + n S + n + π + were measured detecting electron and pion in coincidence at an invariant hadronic mass of 2.19 GeV. The measurements were performed at electron four-momentum transfer squared of f 2 = 0.70 and 1.35 GeV 2 in the range of t = ( γ v − π ) 2 between t min and −1.0 GeV 2 . The cross section d 2 σ / dtdφ of the reaction e + n → e' + p + π − was determined.
ACTUALLY RATIO OF PI- TO PI+ PRODUCTION OFF DEUTERIUM.
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At the Bonn 2.5 GeV electron synchrotron the angular distribution of the target asymmetry T = (σ↑ − σ↓) (σ↑ + σ↓) for the reaction γp↑ → π + n was measured at a mean photon energy of 700 MeV and pion CM-angles from 50° to 155°. The combination of a 3 He-cryostat, polarizing the free protons in the target up to 65%, with a large acceptance magnet for pion detection led to statistical errors of the target asymmetry comparable with those of cross section measurements.
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A partial wave analysis of the K 0 π + π − system produced in the charge exchange reaction K − p → ( K 0 π + π − ) n at 4.2 GeV/ c has been performed both as a function of Kππ mass and of t ′. The 1 + S wave forms the largest contribution to the K ππ system and peaks at roughly the same mass as the Q in diffractive K ππ production. The polarization properties of the 1 + S ( K ∗ π) and 1 + S (Kϱ) waves differ fromt those of the diffractive 1 + wave. There is some evidence for a resonance contribution to 1 + S ( K ∗ π) . The strong 2 + wave the K ∗ (1420) and the K ϱ/ K ∗ ϱ decay branching ratio determined to be 0.36±0.10. An enhancement with spin-parity 1 − is observed under K ∗ (1420) .
CROSS SECTION CORRECTED FOR BREIT-WIGNER TAILS, THE TP CUT, UNSEEN <AK0 PI> AND <K RHO> DECAY MODES. BRANCHING RATIO K*(1420) --> <K RHO>/<K* PI> = 0.36 +- 0.10.
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Measurements of the polarised beam asymmetry parameter Σ for eta photoproduction from protons, have been carried out at incident energies of 2.5 GeV and 3.0 GeV, and for various t -values between −0.2 (GeV/c) 2 and −1.2 (GeV/c) 2 . The values of Σ are close to +1 for values of | t | less than 0.7 (GeV/c) 2 , showing that there can be little contribution from unnatural parity exchange in any Regge exchange model of the process, in disagreement with present theories. Differential cross sections for the process werre also measured, and are consistent with those from other experiments.
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Based on a sample of about 3500 events, we have measured the total and differential cross sections of p p → n n in the 700–760 MeV/ c incident momentum region. It is found that σ CE = 10.7 ± 0.2 mb at the average momentum of 730 MeV/ c . The differential angular distribution is characterised by a sharp peak and a dip in the forward direction followed by a secondary maximum. The position of the dip corresponds to | t | ≈ m π 2 . These results are compared with the predictions of the model of Bryan-Phillips. On the other hand, this dip-bump structure can be well understood on a simple picture involving a π exchange and a constant background (for | t | ≲ 3 m π 2 ).
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Elastic scattering of 32.1 GeV/ c K + on protons has been measured in a bubble chamber experiment. Results are presented in the momentum transfer interval 0.06–1.40 GeV 2 and compared with data at different energies. An effective Regge trajectory is calculated using K + p elastic data from 10 to 175 GeV/ c .
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The Λ p total cross section has been measured in the Λ momentum range 4–14 GeV/c. The weighted mean of the cross section over this momentum interval is σ( Λ p) = 49.3 ± 3.7 mb for an average Λ momentum of 8.3 ± 2.7 GeV/ c . This value differs from the corresponding value for σ(Λp) measured previously by 14.5 ± 3.8 mb. Assuming a variation with Λ momentum, pΛ , of the form σ( Λ p) − σ(Λp) = σ 1pΛ − 1 2 , a value of σ 1 = 47 ± 10 mb GeV − 1 2 is obtained.
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The results of a study of the reaction π-p→π-π-π+p at2 147 GeV/c carried out at the Fermilab Proportional Wire 30″ Bubble Chamber Hybrid Spectrometer are reported. More than 92% of the cross-section ((670±41) μb) for this reaction is contained in those for proton and pion diffraction dissociation. The cross-sections for pion diffraction events with three-pion invariant mass in given regions are in agreement with values obtained by extrapolation of fits to data at lower incidentpion momenta. ρ0π- events make an important contribution in the A1 and A2 mass regions, and the data are consistent with contributions from f0π- in the A3 mass region. The cross-section for proton diffraction events is in agreement with a smooth extrapolation of the data at lower momentum.
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The results presented in this paper were obtained from a 105 000 frame exposure of the FNAL Hybrid Proportional Wire Chamber-30 inch Bubble Chamber System, in a tagged beam of 147 GeV/ c negative particles. Elastic, total and topological cross sections were obtained for both π − p and K − p interactions. Comparisons with other data, taken with various beam particles over large momentum intervals, show good agreement with KNO scaling, and similarity in the scaling behavior of σ n for the different beam particles.
THESE CROSS SECTIONS ARE NOT NORMALIZED TO ANY OTHER ABSOLUTE MEASUREMENT. THE ERRORS INCLUDE SOME SYSTEMATIC ERRORS.
THE FORWARD CROSS SECTION AGREES WELL WITH THE OPTICAL POINT FROM TOTAL CROSS SECTION MEASUREMENTS.
THESE CROSS SECTIONS ARE NOT NORMALIZED TO ANY OTHER ABSOLUTE MEASUREMENT.
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