Measurements of complete angular distributions of elastic K + p scattering at closely spaced incident momenta from 1368 to 2259 MeV/ c are presented and discussed. A PDP-8 computer controlled system of scintillation counters and core-readout wire spark chambers was used for the detection of elastic events. Diffractive behaviour is already present at the lowest measured momentum and becomes more prominent as the incident momentum increases. An expansion of the angular distributions in terms of Legendre polynomials shows no marked structure of the expansion coefficients as functions of the incident momentum. Our measurements can be adequately described by a number of existing phase shift solutions within 5% of their published values. Also Regge pole extrapolations represent our data satisfactorily.
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Data on the inclusive production spectra of K S 0 and Λ from proton-proton collisions at 19 GeV are presented and discussed in connection with the earlier studied inclusive π − production spectrum. The three single-particle spectra are compared with a crude two-center thermal model for the average radiation from the pp collisions.
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The reaction K − p → X K − p has been measured at 25 and 40 GeV/ c at the Serpukhov accelerator using the CERN-IHEP boson spectrometer. At both energies we observe production of the resonances K ∗− (890) and K ∗− (1420) in the channels K ∗− → K 0 π − and K − π 0 ; the momentum dependence of their production cross sections is found to be σ[ K ∗− (890)] ∞ p inc −1.48±0.04 and σ [ K ∗− (1420)] ∞ p inc −0.8±0.2 .
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The neutron-proton elastic differential cross section has been measured with high statistics for incident momenta between 10 and 24 GeV/ c using wire spark chambers for the neutron detection. The t -range covered by previous experiments could thus be extended to 0.06–3 (GeV/ c ) 2 . In this t -interval the np cross section is found to be very similar to the corresponding pp cross section.
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Final state resonance production and single particle momentum spectra are presented for p p annihilations into K K and π's between 1.09 and 3.45 GeV/ c . Resonance production generally agrees with the Lamb statistical model. Momentum spectra of K's and π's are independent of incident energy, while the mean multiplicity increases in proportion to the c.m. energy, supporting the annihilation model of Jacob and Nussinov.
THESE CROSS SECTIONS WERE GIVEN IN DETAIL IN B. Y. OH ET AL., NP B51, 57 (1973).
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In an experiment with the CERN 2m deuterium bubble chamber the reaction K + d→K o pp (1) and the related reaction K + n→K o p (2) are studied at an incident momentum of 4.6 GeV/ c . The cross section for the latter reaction is found to be slightly larger than the cross section for the reaction K − p → K o n at the same energy. The corresponding differential cross sections agree within the rather large uncertainties. The forward amplitude for reaction (2) is predominantly real. Moreover, the total and forward differential charge exchange cross section values are compatible with those predicted on the basis of an SU (3) sum rule. A comparison of the K ± -charge exchange differential cross sections with the predictions of a Regge pole model is also presented.
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SMALL -T DEUTERIUM CORRECTION APPLIED USING MC GEE WAVE FUNCTION (PAPER ALSO GIVES UNCORRECTED AND HULTHEN CORRECTED DATA).
The differential cross section has been measured using 940 events from the BNL 30-inch deuterium bubble chamber. Events were selected without regard to length of the deuteron, and so wide-angle scatters are included. The data are fitted well by a Glauber model with reasonable assumptions about the parameters.
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INTEGRATED CROSS SECTION USING EXPONENTIAL FIT TO FORWARD PEAK (SLOPE = 25.2 +- 1.4 GEV**-2).
We have studied the K ππ system in the 14.3 GeV/ c reactions K − p → K − π + π − p, K − p → K 0 π − π 0 and K − p → K 0 π + π − n . The data have been obtained from a 500 000 picture exposure of the CERN 2m HBC. The first two final states are dominated by Q-production in the Kππ system; there is also an L-signal at M (K ππ ) ∼ 1.75 GeV. The reaction cross sections are compared to K − p data at other energies. We discuss the K ππ mass dependence of the diffractive production slope. Evidence is presented for a Q − p versus Q + p differential cross section cross-over around | t | = 0.17 GeV 2 . A t -channel isospin analysis for the KN → K ∗(890)π N channels in the Q-region shows that the I = 1 exchange amplitude is ⋍ 10% of the dominant I = 0 exchange amplitude. The K ππ decay distributions indicate a predominant J P = 1 + state in the Q-region, and an important J P = 2 − contribution in the L-region. We find neither s -channel nor t -channel helicity conservation at the meson vertex in the Q- or L-regions. The K π angular correlation moments within the K ππ diffractive system are characteristic of K π elastic scattering, suggesting a π -exchange Deck-type production mechanism. There is evidence for a Kf 0 and κπ contribution (where κ is the J P (K π ) = 0 + state) to the diffractive K ππ system. A fit to the K − π + π − and K 0 π − π 0 Dalitz-plot distributions for the Q-re gion indicates that the ratio of K ϱ to K ∗ π decay amplitudes decreases with increasing K ππ mass.
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Helicity conservation in the reaction π − p → pA 1 at 4.45 GeV/ c has been studied using 50 cm and 55 cm liquid hydrogen bubble chambers. In the Jackson and the helicity frames the dependence of the ϱ matrix elements on the four-momentum transfer squared to the proton ( t ) for A 1 maximum decay has been calculated. The obtained data are in a good agreement with t -channel helicity conservation. The t -channel dependence of the ϱ matrix elements in the mentioned frames is in good agreement with that calculated using the Regge π-pole exchange model (it is suggested that the A 1 maximum nature is explained by a kinematical effect of the Deck type).
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Pions from the reaction γ + p → π + + n were analysed in the backward direction by a magnetic spectrometer. The photon energy region of 0.394 GeV to 1.397 GeV was covered by 19 different momentum settings. Data reduction resulted in 74 measured differential cross sections with statistical uncertainties typically from 4% to 8%. The systematic uncertainty was estimated to be ±5%. The data are compared to other recent experiments and predictions of phenomenological analyses.
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