Both the np and the pp analyzing powers were measured simultaneously using the SATURNE II polarized deuteron beam at 0.550, 0.725, 0.900 and 1.15 GeV/nucleon. The results for the pp analyzing power coincide with the free pp elastic scattering data. We thus can assume that also the np analyzing power is equal to the one for scattering of free polarized neutrons. The np data cover the angular region 90° ≤ θ CM ≤ 125°. Our results for the np analyzing power clarify a discrepancy between earlier data at 0.5 GeV and allow conclusions about the energy dependence of the minimum of polarization at θ CM ⋍ 100° in the region from 0.5 to 0.9 GeV.
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The pp analyzing power was measured using the SATURNE II polarized proton beam and the Saclay frozen spin polarized target. The measurements at 0.88 and 1.1 GeV were carried out in the angular region θ CM from 28° to ≅50° and complete our previous measurements from 45 ° to 90°. Above 1.1 GeV the measurements presented here cover both regions, extending from θ CM = 28° (at the lower energies) or θ CM = 18° (at the higher energies) to θ CM > 90°. The shape of the angular distribution A oono ( pp ) = ƒ(θ CM ) changes considerably with increasing energy. The new data show the onset of a characteristic t -dependence of the analyzing power, with a minimum at − t ≅ 1.0 (GeV/ c ) 2 followed by a second maximum at − t ≅ 1.5 (GeV/ c ) 2 . This structure is present at all energies, from kinematic threshold to 200 GeV.
Errors are statistical plus random-like instrumental uncertainties. Results using polarised target.
Errors are statistical plus random-like instrumental uncertainties. Results using polarised target.
Errors are statistical plus random-like instrumental uncertainties. Results using polarised target.
We report Λ 0 -hyperon polarization measurements at the CERN intersecting storage rings from √ s of 31 to 62 GeV. P Λ 0 changes insignificantly, +(0.8±1.7)%, over this range of √ s . However, P Λ 0 is observed to grow with Feynman- x F and with transverse momentum. At an average p t of 1.1 GeV/ c , P Λ 0 depends linearly on x F and approaches −40% at x F =0.8.
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TheA-dependence of the polarization ofΛ0,s produced inclusively in neutron-nucleus interactions at a mean neutron momentum of about 40 GeV/c has been measured in an experiment performed using the BIS-2 spectrometer at the Serpukhov accelerator. Carbon, Aluminium and Copper targets were used. TheΛ0,s were produced in the kinematical region of 0.6
POLARIZATION IS DESCRIBED BY A POWER LOW: POL = C*A**B, WHERE C = -1.1, +0.4, -0.3 , A- ATOMIC NUMBER AND B = -0.15, +0.07, -0.6.
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We have measured the difference between the pp total cross sections for parallel and antiparallel longitudinal spin states at beam momenta of 2.75, 2.92, 3.25, and 3.48 GeV/c. These results reveal possible new structure in this momentum range.
Data read from graph. Statistical errors only.
Final results are presented of the proton-proton elastic-scattering spin parameters CSS=(S,S;0,0) and CLS=(L,S;0,0) for thetac.m.=8°–49° and of CLL=(L,L;0,0) for thetac.m.=8°–90° at 11.75 GeV/c. Comparisons to theoretical models are also made.
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The polarization of Λ0 hyperons in inclusive production by 12-GeV protons on nuclei has been measured for beryllium, copper, and tungsten targets. Data are obtained at five production angles, 3.5°, 5.0°, 6.5°, 8.0°, and 9.5°, covering the kinematic range 0.26≤xF≤0.77 and 0.4≤pT≤1.5 GeV/c. The dependence of the polarization on target nuclei is investigated by statistical analyses of the data. The polarization at fixed pT increases roughly linearly with xF. The present results are compared with other work at higher energies in terms of the A dependence and the (xF,pT) dependence.
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The polarization of Ξ− hyperons produced by 400-GeV protons in the reaction p+Be→Ξ−+X has been measured as a function of momentum at two production angles. The average polarization for the full sample (192 110 events) was -0.108±0.007. Comparisons are made with polarization measurements for other hyperons produced under similar conditions. From the same data, αΛαΞ was measured to be -0.303±0.004±0.004, where αΛ is the asymmetry parameter in the decay Λ→pπ−, αΞ is the asymmetry parameter in the decay Ξ−→Λπ−, and the uncertainties are statistical and systematic, respectively. This yields αΞ=-0.472±0.006±0.011, where the systematic uncertainty is dominated by the uncertainty in αΛ. An updated test of the ΔI=1/2 rule in Ξ decay is presented.
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Angular distributions of the spin-correlation parameters Asl and All for the reaction pp→π+d have been measured at pion center-of-mass angles 40°≤θπ+*≤130° at incident energies of 500, 650, and 800 MeV. Additional measurements of All were made at 600, 700, and 750 MeV. The results of the experiment are compared with the predictions of several unified coupled-channel calculations and partial-wave analyses. While the latest partial-wave analyses were found to fit the data reasonably well, all except one of the various model predictions not only do not fit the data well, but also tend to be in disagreement with each other. The data show no clear sign of a need for proposed dibaryon resonances.
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