The polarization of Ξ¯ + hyperons produced by 800-GeV/c protons in the inclusive reaction p+Be→Ξ¯ ++X has been measured. The average polarization of the Ξ¯ +, at a mean xF=0.39 and pt=0.76 GeV/c, is -0.097±0.012±0.009. The magnetic moment of the Ξ¯ + is 0.657±0.028±0.020 nuclear magneton.
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We have studied the polarization of Ξ− and Ω− hyperons produced by high energy neutral particle beams. An unpolarized neutral beam striking a target at ±1.8 mrad produced 1.4×107Ξ−'s with an average momentum of 395 GeV/c which were unpolarized, within a sensitivity limit of 0.007, and 2.2 × 105 Ω−'s with a polarization of +0.042±0.007 at an average momentum of 374 GeV/c. A polarized neutral beam striking a target at 0.0 mrad produced 7.1×105Ξ−'s which had a polarization of -0.118±0.004 at an average momentum of 393 GeV/c and 1.8 × 104 Ω−'s with a polarization of -0.069±0.023 at an average momentum of 394 GeV/c. The polarized neutral beam measurement is in good agreement with a previous measurement. The unpolarized neutral beam results are not understood in the context of the current models of hyperon polarization.
Unpolarized neutral beam.
Unpolarized neutral beam.
Polarized neutral beam.
The fixed-target MIPP experiment, Fermilab E907, was designed to measure the production of hadrons from the collisions of hadrons of momenta ranging from 5 to 120 GeV/c on a variety of nuclei. These data will generally improve the simulation of particle detectors and predictions of particle beam fluxes at accelerators. The spectrometer momentum resolution is between 3 and 4%, and particle identification is performed for particles ranging between 0.3 and 80 GeV/c using $dE/dx$, time-of-flight and Cherenkov radiation measurements. MIPP collected $1.42 \times10^6$ events of 120 GeV Main Injector protons striking a target used in the NuMI facility at Fermilab. The data have been analyzed and we present here charged pion yields per proton-on-target determined in bins of longitudinal and transverse momentum between 0.5 and 80 GeV/c, with combined statistical and systematic relative uncertainties between 5 and 10%.
The production yields of PI+ and PI- and the ratio of these yields. The first uncertainty given on each value combines statistical uncertainties and systematic uncertainties from backgrounds.
This paper describes a measurement of the neutron-proton differential cross section made at the Argonne National Laboratory Zero Gradient Synchrotron. The differential cross sections, based on about 470 000 events, are presented for 8 different momentum ranges between 4.5 and 12.5 GeV/ c . The data extend from small angles out to about 145° in the c.m.s., corresponding to 0.14 < − t ⪅ 19 (GeV/ c ) 2 at the highest energies. These results in conjunction with previous np charge-exchange data provide almost complete angular distributions in this momentum range. A detailed comparison of the data with existing pp data and with theoretical predictions is made.
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We have measured cross sections for forward neutron production from a variety of targets using proton beams from the Fermilab Main Injector. Measurements were performed for proton beam momenta of 58 GeV/c, 84 GeV/c, and 120 GeV/c. The cross section dependence on the atomic weight (A) of the targets was found to vary as $A^(alpha)$ where $\alpha$ is $0.46\pm0.06$ for a beam momentum of 58 GeV/c and 0.54$\pm$0.05 for 120 GeV/c. The cross sections show reasonable agreement with FLUKA and DPMJET Monte Carlos. Comparisons have also been made with the LAQGSM Monte Carlo.
Total inelastic PP cross section.
Average multiplicities and production cross section for neutral particles from PP interactions at 84 GeV.
Cross sections for neutron production greater than threshold and within an angular range of 20.4 mrad.
Neutron-proton differential cross sections have been measured with good statistics for four-momentum transfers 0.14<−t≲19.0 (GeV/c)2 at laboratory momenta ranging from 4.5 to 12.5 GeV/c. The experiment was carried out in a neutron beam at the Argonne National Laboratory zero-gradient synchrotron. These results in conjunction with previous n−p charge-exchange data provide almost complete elastic-scattering angular distributions in this momentum range.
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We report the results of an experiment which measured n-p elastic scattering differential cross sections over a range in -t from 0.15 to ~ 3.6 (Gev/c)2 for incident neutron momenta from 70 to 400 GeV/c. We find the logarithmic slope parameter, evaluated at -t = 0.2 (GeV/c)2, to be consistent with existing proton-proton parameterizations. The data exhibit a dip in the cross section near -t 1.4 (Gev/c)2 for incident neutron momenta above 200 Gev/c. For neutron momenta less than 280 GeV/c, the neutron-proton cross sections are found to be higher than existing proton-proton data in the range 0.7 ~ -t ~ 1.3 (Gev/c)2 which is in contradic- tion to most Regge predictions.
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In a beam-dump experiment at Fermilab the cross section for charm-particle production has been deduced from a measurement of the prompt neutrino flux. The reaction cross section, if we assume only DD¯ and the dependence on atomic weight A0.75, is 57.2 ± 2.9 ± 8.5 μb/nucleon and the dependence on Feynman x and transverse momentum is EDd3σdpD3∝(1−x)3.2e−1.5p⊥ (p⊥ in GeV/c). The data are consistent with as much as 40% diffractive production of ΛcD¯.
Assuming only (D AD) production and branching ratio BR(D--> NU) = 0.101.
Assuming both (D AD) and (LAMBDA/C AD) production.
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