The reaction K − n → K − π + π − n has been studied in the SLAC 82″ liquid deuterium bubble chamber with a beam momentum of 12 GeV/ c . Although the kinematic fit for this final state has only one constraint, nonetheless a reasonably pure sample has been obtained. The cross section for the reaction is 1.02 ± 0.10 mb. The process K − n → K ∗0 890 Δ − is observed with cross section 36 ± 9 μ b and t -slope of 10 ± 2 (GeV/ c ) −2 . A kaon diffraction dissociation sample has been obtained, although the Q-signal is not so strong as in experiments with proton targets. Neutron dissociation into n π + π − is also observed with similar properties to those of proton dissociation into p π + π − , but with a broader t -distribution.
BEAM AND TARGET DIFFRACTION DISSOCIATION DATA ARE REPORTED.
The diffractive dissociation of a 200-GeV/c π− beam into KS0KS0π+π−π− has been observed. The diffractive KS0KS0π+π−π− cross section is 1.59±0.78 μb. The ratio of the diffractive KS0KS0π+π−π− cross section to the diffractive KS0KS0π− cross section is 0.40±0.13, which is in good agreement with a diffractive-fragmentation-model prediction of 0.36. There is evidence for simultaneous production of K*− and K*+ in the diffractive KS0KS0π+π−π− sample. The K*+−KS0π−+ mass distribution shows an enhancement near 1.95 GeV.
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Elastic scattering of p¯ on p has been studied for cosθc.m. between -0.88 and -1.0 and Plab(p¯) between 0.70 and 2.16 GeV/c. The momentum dependence of the cross section shows a sharp dip at 0.9 GeV/c and a broad peaking around 1.4 GeV/c. The possibility of the peak resulting from direct formation of boson resonances has been studied. Alternatively, a diffraction model agrees qualitatively with our data and other elastic data at different angles.
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Measurements have been made of the differential cross section for p p elastic scattering over a c.m. angular range −0.95 ⩽ cos θ ∗ ⩽ 0.93 at 21 incident antiproton momenta between 0.69 GeV/ c and 2.43 GeV/ c (c.m. energy 1.96–2.58 GeV). About 10 5 events were obtained at each momentum. The results are discussed primarily in terms of the formation of s -channel resonances in the T and U mass regions, and within the context of the optical model of Frahn and Venter.
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An experimental analysis of p p interactions between the p p threshold (√ s = 1878 MeV) and √ s = 2 100 MeV leads to clear evidence for an s -channel effect in the reaction p p → π + π − π + π − π 0 at 1949 ± 10 MeV /c 2 (Γ ⋍ 80 MeV /c 2 ) . A comparison is made with the backward elastic scattering and charge-exchange behaviour. An interpretation in terms of an object strongly coupled to mesonic decay modes, with small or middle-sized elasticity ( x ⩽ 0.135 −0.06 +0.13 ) is given. No significant narrow structure is observed in the backward elastic scattering between 1.9 and 2 GeV. The experimental resolution of √ s in this case is 2 MeV.
LOWER MOMENTUM RESULTS WERE REPORTED IN CH. D'ANDLAU ET AL., PL 58B, 223 (1975). TABULATED NUMERICAL VALUES OF DATA ON FIGURES SUPPLIED BY M. LALOUM.
We report on experimental results on deuteron-deuteron elastic scattering at a centre-of-mass energy of √ s = 53 GeV . The data were obtained using the Split Field Magnet detector at the CERN intersecting Storage Rings. The t -dependence of the elastic cross section is measured up to − = 1.5 GeV 2 . We observed a narrow interference minimum in the differential cross section at − = 0.18 GeV 2 . The inclusion of inelastic intermeduate states in the multiple scattering Glauber theory is essential in the description of the data over the entire t -range where discrepancies of up to 25% are observed with the basic theory.
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The negative kaon electromagnetic form factor has been measured in the space-like q 2 range 0.015–0.10 (GeV/ c ) 2 by the direct scattering of 250 GeV kaons from electrons at the CERN SPS. It is found that the kaon mean square charge radius 〈 r 2 K 〉 = 0.34 ± 0.05 fm 2 . From data collected simultaneously for πe scattering, the difference between the charged pion and kaon mean square radii (which is less sensitive to systematic errors) is found to be 〈 r 2 π 〉 − 〈 r 2 K = 0.1 0 ± 0.045 fm 2 .
Ratio is assumed free of systematic error.
Measurements of proton-deuteron scattering have been performed using an incident 24.0 GeV/ c proton beam. Momentum-loss spectra of forward-scattered protons were measured by a single-arm spectrometer over a range of proton angles from 13 to 107 mr. The contributions to the proton spectra of single and double scattering can be separated experimentally, thus allowing estimates of proton-neutron elastic cross sections to be deduced from the data over a range of four-momentum transfer squared, |t| 5.8 GeV 2 . Elastic p - d scattering, in which the proton and deuteron were detected in coincidence, has also been measured over a range of | t | from 0.6 to 1.8 GeV 2 .
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EXTRACTED FROM SINGLE AND DOUBLE PEAK DEUTERIUM DATA BY THE GLAUBER METHOD WITH FERMI MOTION CORRECTIONS.
A tagged medium-energy neutron beam has been used in a precise measurement of the absolute differential cross section for np back-scattering. The results resolve significant discrepancies within the np database concerning the angular dependence in this regime. The experiment has determined the absolute normalization with 1.5% uncertainty, suitable to verify constraints of supposedly comparable precision that arise from the rest of the database in partial wave analyses. The analysis procedures, especially those associated with evaluation of systematic errors in the experiment, are described in detail so that systematic uncertainties may be included in a reasonable way in subsequent partial wave analysis fits incorporating the present results.
Final differential cross sections averaged over data samples.
Measurements of the spin transfer parameters, K NN and K LL , at 500, 650 and 800 MeV are presented for the reaction p d → n pp at 0°. The data are useful input to the NN data base and indicate that the quasi-free charge exchange (CEX) reaction us a useful mechanism for producing neutrons with at least 40% polarization at energies as low as 500 MeV.
QUASI-FREE NP ELASTIC SCATTERING.
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