Interactions of 683-MeV/c negative pions with protons were investigated using the BNL 14-in. hydrogen bubble chamber in a 17-kG field. Two thousand elastic scatterings were analyzed, yielding a cross section of 18.9±1.0 mb. No evidence for powers of cosθ higher than the second was observed in the elastic angular distribution. The angular distribution obtained was dσdω=(0.384±0.026)+(1.70±0.06)cosθ+(3.36±0.11)cos2θ mb/sr. The single-pion production reactions π−+p→π−+π0+p and π−+p→π−+π++n were studied in detail. A total of 441 π0 productions and 833 π+ productions were analyzed giving cross sections of 3.99±0.50 and 7.50±0.80 mb, respectively. The differential distributions for these inelastic processes are presented and compared with the predictions of the model of Olsson and Yodh. The distribution of events on the Dalitz plots for π0 production is accounted for by the model. However, for the π+ reaction, the model (so far developed) does not describe adequately the distribution of events on the Dalitz plot. In particular, the model fails to account for the enhancement at high (π+π−) effective masses in ππ mass distribution. The center-of-mass angular distributions for π0 and π+ production reactions are presented and compared with the model.
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The cross section for production of ρ0 mesons has been measured in the reaction e+p→e+p+π++π−. The cross section is presented as a function of W, the c.m. energy of the virtual-photon-proton system, and -Q2, the square of the virtual-photon mass. The vector-dominance model is not able to describe the dependence of the cross section on the parameters Q2 and W. The slope parameter B describing the scattering of the proton exhibits a significant variation with Q2.
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The production of the ω meson by virtual photons has been measured as a function of Q2 and W. The ratio of ω production to ρ0 production is independent of Q2 in contrast to indications at lower values of W.
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The cross section for the fully constrained reaction ep→eppp¯ has been determined as a function of the electroproduction variables Q2 and s, in the range 0.7<Q2<3 GeV2 and 8<s<16 GeV2. Evidence is presented and cross-section estimates are made for resonances in the final-state p¯p system.
The cross section for virtual photon are derived from E- P cross section bydividing on the virtual-photon flux factor.
The cross section for virtual photon are derived from E- P cross section bydividing on the virtual-photon flux factor.
Charged-particle multiplicity distributions in 400-GeV/c pd interactions have been studied in an experiment in the Fermilab 30-inch bubble chamber. From the fractions of odd-prong and backward-proton events, a rescatter fraction of 0.22±0.01 is found (for N≥3). The pn multiplicity distribution is obtained from the odd-prong distribution plus a no-cascade assumption. After making one-prong and two-prong estimates, mean charged-particle multiplicities of 9.49±0.12 for pd (including slow particles) and 8.57±0.12 for pn are obtained. In the incident momentum range 100 to 400 GeV/c, pd and pp distributions are very similar to each other and are different from pn distributions.
Axis error includes +- 0.0/0.0 contribution (?////SHORT PROTON VISIBILITY, UNOBSERVED DALITZ PAIRS, UNOBSERVED VEES, UNOBSERVED CLOSE SECONDARIES, UNCOUNTABLE EVENTSTHE ONE- AND TWO-PRONG EVENTS WERE NOT MEASURED AND WERE ESTIMATED USING ADDITIONAL ASSUMPTIONS AND DATA OF OTHER EXPERIMENTS//TO OBTAIN THE FREE-NEUTRON DISTRIBUTIONS THE ASSUMPTION THAT RESCATTERING IS MULTIPLICITY INDEPENDENT HAS BEEN MADE, AND CORRECTION FOR DEUTERON-FINAL-STATE EVENTS AND FOR WAVE-FUNCTION SYMMETRY REQUIREMENTS HAS BEEN MADE).
Axis error includes +- 0.0/0.0 contribution (?////SHORT PROTON VISIBILITY, UNOBSERVED DALITZ PAIRS, UNOBSERVED VEES, UNOBSERVED CLOSE SECONDARIES, UNCOUNTABLE EVENTSTHE ONE- AND TWO-PRONG EVENTS WERE NOT MEASURED AND WERE ESTIMATED USING ADDITIONAL ASSUMPTIONS AND DATA OF OTHER EXPERIMENTS//TO OBTAIN THE FREE-NEUTRON DISTRIBUTIONS THE ASSUMPTION THAT RESCATTERING IS MULTIPLICITY INDEPENDENT HAS BEEN MADE, AND CORRECTION FOR DEUTERON-FINAL-STATE EVENTS AND FOR WAVE-FUNCTION SYMMETRY REQUIREMENTS HAS BEEN MADE).
Axis error includes +- 0.0/0.0 contribution (?////SHORT PROTON VISIBILITY, UNOBSERVED DALITZ PAIRS, UNOBSERVED VEES, UNOBSERVED CLOSE SECONDARIES, UNCOUNTABLE EVENTSTHE ONE- AND TWO-PRONG EVENTS WERE NOT MEASURED AND WERE ESTIMATED USING ADDITIONAL ASSUMPTIONS AND DATA OF OTHER EXPERIMENTS//TO OBTAIN THE FREE-NEUTRON DISTRIBUTIONS THE ASSUMPTION THAT RESCATTERING IS MULTIPLICITY INDEPENDENT HAS BEEN MADE, AND CORRECTION FOR DEUTERON-FINAL-STATE EVENTS AND FOR WAVE-FUNCTION SYMMETRY REQUIREMENTS HAS BEEN MADE).
A search has been made for direct photon production in pBe interactions at 200 and 300 GeV/ c over the kinematic region 1.5 < P ⊥ < 4.0 GeV/ c and −0.7 < X F < 0 (90° < θ cms < 160°). An excess of single photons above that which is predicted from the measured π 0 and η 0 production is observed. Theratio of γ / π 0 production is calculated assuming that the excess arises from direct photon production. We find that this ratio averages 0.070 ± 0.025 (including systematic errors) in this region of X F and P ⊥ for our 200 and 300 GeV/ c data. We have used our measured value of the η / π 0 ratio of 0.47 ± 0.10 in the determination of the γ / π 0 ratio. The variation of γ / π 0 with X F , P ⊥ , X R and θ cms presented.
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We have used the ratio between the production rates of $K^0$'s and $π^−$'s in antineutrino-nucleon interactions in the Fermilab 15 ft bubble chamber to measure the size of the SU (3) symmetry violation in the production of quark-antiquark pairs to be 0.27 ± 0.04. This value is significantly larger than the value obtained from a recent ep experiment. There is no apparent dependence of the $K^0$/$π^−$ ratio with $W^2 , Q ^2 , x_b$ or $p_T^2$ .
OBTAINED RESULT FOR SIG/SIG IS MODEL DEPENDENT.
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The results of a study of strange particle production in charged current $\bar{\nu}_{\mu} N$ interactions in the Fermilab 15 ft bubble chamber filled with a heavy $Ne-H_2$ mixture are presented. Production rates and average multiplicities of $K^0$'s and Λ's as functions of W 2 and Q 2 are given. The experimental data agree well with the quark-parton model predictions if a yield of 0.06 ± 0.02 of $K^0$'s and Λ's from charm production is included. Upper limits for D-meson production are given and the shape of the charmed quark fragmentation function is discussed. Inclusive production of the K ∗ (890) and Σ(1385) resonances is measured and it is shown that only about 5% of the K 0 mesons and Λ hyperons results from resonance decays. Relative production rates of neutral strange particles on proton and neutron targets are studied.
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We present results on inclusive particle production in the antineutrino charged current induced hadron jets observed in the Fermilab 15 ft bubble chamber. Fractional energy distributions, particle ratios and average multiplicities of the hadrons in the jets are measured. Ratios between the inclusive production rates of different mesons in the jets are studied to seek evidence for the d-quark origin of the observed hadrons. Good over-all agreement with the hypothesis of d-quark fragmentation with universal fragmentation functions obeying isospin systematics is established.
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