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The polarization and angular distribution of protons scattered from protons, helium, beryllium, carbon, aluminum, calcium, iron, and tantalum were measured as functions of angle at 725 MeV. A variation of the usual double-elastic-scattering method was used, in that the sense of the first scattering angle was reversed in finding asymmetries, rather than the second angle. Energy analysis of the scattered beam was accomplished by means of a 102-degree magnetic spectrometer allowing a total resolution of ±10 MeV. The data were fitted with an optical model. In the proton-nucleus scattering the polarization reaches a maximum value of about 40% at angles less than the diffraction minimum. Results in proton-proton scatterings are more interesting; however, because of an uncertainty in the analyzing power of carbon, a definite statement cannot be made. One can say, however, that either the polarization in proton-proton scatterings is above 50% at this energy or the analyzing power of carbon at 6 deg and 600 MeV is more than 40%, which is considerably greater than the 30% measured at 725 MeV.
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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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Differential cross sections for elastic π−p scattering were measured at eight energies for positive pions and seven energies for negative pions. Energies ranged from 310 to 650 MeV. These measurements were made at the 3-GeV proton synchrotron at Saclay, France. A beam of pions from an internal BeO target was directed into a liquid-hydrogen target. Fifty-one scintillation counters and a matrix-coincidence system were used to measure simultaneously elastic events at 21 angles and charged inelastic events at 78 π−p angle pairs. Events were detected by coincidence of pulses indicating the presence of an incident pion, scattered pion, and recoil proton, and the results were stored in the memory of a pulse-height analyzer. Various corrections were applied to the data and a least-squares fit was made to the results at each energy. The form of the fitting function was a power series in the cosine of the center-of-mass angle of the scattered pion. Integration under the fitted curves gave values for the total elastic cross sections (without charge exchange). The importance of certain angular-momentum states is discussed. The π−−p data are consistent with a D13 resonant state at 600 MeV, but do not necessarily require such a resonant state.
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The elastic, the pion-production, and the multipion-annihilation cross sections for antiproton-proton interactions at 3.28 and 3.66 BeV/c incident antiproton momenta have been measured. A comparison of the elastic interactions at 3.28 BeV/c with a purely-absorbing disc optical model gave a best value for the radius of interaction of 1.3 F. The real part of the forward scattering amplitude has been found to be less than 20% of the imaginary part. A study of the asymmetries in double elastic scatters yielded a value for a polarizing power of the hydrogen consistent with zero when averaged over production angles.
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Angular distributions for π0 photoproduction from hydrogen at energies between 660 and 800 MeV and proton center-of-mass angles from 0° to 140° have been measured and analyzed. Some variation from a pure d32 state is seen in the resonance region. A possible high-momentum-transfer enhancement of the cross section is discussed.
Axis error includes +- 0.0/0.0 contribution (3 TO 10////).
Axis error includes +- 0.0/0.0 contribution (3 TO 10////).
Axis error includes +- 0.0/0.0 contribution (3 TO 10////).
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Twenty-nine proton-proton differential elastic cross sections for lab momenta p0 from 11 to 31.8 BeV/c, at four-momentum transfers squared, −t, from 2.3 to 24.4 (BeV/c)2, have been measured at the Brookhaven alternating gradient synchrotron. The circulating proton beam impinged upon a thin CH2 internal target. Both scattered protons from p−p elastic events were detected by scintillation-counter telescopes which were placed downstream from deflection magnets set at the appropriate angles to the incident beam. The angular correlation of the protons, their momenta, and the coplanarity of the events were determined by the detection system. The results show that at high momentum transfers the differential cross section, dσdt, depends strongly upon the energy; for −t=10 (BeV/c)2, the value of dσdt at p0=30 BeV/c is smaller by a factor∼1000 than at p0=10 BeV/c. At all energies, dσdt falls rapidly with increasing |t| for scattering angles up to about 65° (c.m.), while in the range from 65 to 90° the cross section falls only by a factor of about 2. The smallest cross section measured was 9×10−37 cm2 sr−1 (c.m.), at p0=31.8 BeV/c and −t=20.4 (BeV/c)2; this is about 3×10−12 of the zero-degree cross section at the same energy.
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