The total proton-proton cross section (excluding Coulomb scattering) has been measured at energies from 410 Mev up to 2.6 Bev, using external beams from the Cosmotron. Fast counting equipment was used to measure the attenuation of the beams through polyethylene, carbon, and liquid H2 absorbers. At each energy E, σp−p(E, Ω) was measured as a function of the solid angle Ω subtended by the rear counter at the center of the absorber. The total cross section σp−p was obtained by a least squares straight line extrapolation to Ω=0. The measured σp−p as a function of energy rises sharply from 26.5 mb at 410 Mev to 47.8 mb at 830 Mev and then remains approximately constant out to 1.4 Bev, above which energy it decreases gradually to about 42 mb at 2.6 Bev. Using the same equipment and procedure, we have also measured the D2O-H2O difference cross section, called "σp−n," for protons over the same energy range. From a comparison of "σp−n," and σp−p, with the n−p and n−d measurements of Coor et al. at 1.4 Bev, it is apparent that one nucleon is "shielded" by the other in the deuteron. This effect is not present at energies below 410 Mev. Comparing the measured p−p and "p−n" (corrected) cross sections with the results of other high-energy experiments, one may infer the following conclusions: (1) The sharp rise in σp−p from 400 to 800 Mev results from increasing single pion production, which may proceed through the T=32, J=32 excited nucleon state. (2) Above 1 Bev the inelastic (meson production) p−p cross section appears to be approximately saturated at 27-29 mb. (3) The rise in cross section for n−p interaction in the T=0 state, associated with the rise in double pion production, implies that double meson production also proceeds through the T=32 nucleon state. (4) The probable equality of σp−d and σn−d at 1.4 Bev implies the validity of charge symmetry at this energy.
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As a part of our program to study p−p collisions at Cosmotron energies, the differential cross sections for elastic scattering were measured at five laboratory angles between 2.3° and 17° for each incident energy. Total elastic cross sections obtained by integration are 21.4±1.4, 17.0±0.8, and 14.7±0.7 mb at 1.35, 2.1, and 2.9 BeV, respectively. The angular distribution as a function of the momentum transfer, exhibits a forward diffraction peak, the width of which shrinks slightly as the incident energy increases. The experimental results were fitted by simple optical model calculations and also compared with the predictions of the composite particle theory of Chew and Frautschi.
No description provided.
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The polarization parameter in proton-proton scattering has been measured at incident proton kinetic energies of 1.7, 2.85, 3.5, 4.0, 5.05, and 6.15 BeV and for four-momentum transfer squared between 0.1 and 1.0 (BeV/c)2. The experiment was done with an unpolarized proton beam from the Bevatron striking a polarized proton target. Both final-state protons were detected in coincidence and the asymmetry in counting rate for target protons polarized parallel and antiparallel to the scattering normal was measured. The maximum polarization was observed to decrease from 0.4 at 1.7 BeV to 0.2 at 6.1 BeV. The maximum of the polarization at all energies studied occurs at a four-momentum transfer squared of 0.3 to 0.4 (BeV/c)2.
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The production of N ∗ (1400) isobar in the reaction pp → pN ∗+ (1400), where N ∗ (1400) → n π + and p π 0 , is investigated with the aid of one-pion exchange model. The one-pion exchange mechanism does not seem to dominate the production process. The isospin of N ∗ (1400) is found to be I = 1 2 , and the elasticity of the resonance is estimated to be 0.66.
Axis error includes +- 0.0/0.0 contribution (?////Due to fitting mass spectrum).
Experimental results are presented on the excitation of the nucleon isobars N ∗ (1518) and N ∗ (1688) in proton-proton collisions at an incident momentum of 19.2 GeV/ c and in the range of four-momentum squared 0.6 ⩽7 z . sfnc ; t | ⩽ 5.8 GeV 2 .
Axis error includes +- 0.0/0.0 contribution (?////Due to the method used in estimating the area under the peak).
Axis error includes +- 0.0/0.0 contribution (?////Due to the method used in estimating the area under the peak).
Axis error includes +- 0.0/0.0 contribution (?////Due to the method used in estimating the area under the peak).
Polarization and differential cross section data for elastic proton-proton scattering between 0.86 and 2.74 GeV/ c are presented. A comparison is made with existing phase-shift analyses.
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Proton-proton total cross-sections have been measured at nine different energies between 179 and 555 MeV (607 and 1162 MeV/ c ) with a typical accuracy of 0.9%. The accuracy is limited by a poor knowledge of the Coulomb-nuclear interference region in elastic scattering.
No description provided.
Polarizationdata for the reaction pp → π + d on polarized protons at 1.04, 1.13, 1.21, 1.37 and 1.45 GeV/ c are presented. The coefficient characterizing the angular distribution of the polarization show an energy dependence similar to that of the total cross-section and are consistent with the view that N ∗ ( 3 2 , 3 2 ) production dominates the reaction mechanism.
No description provided.
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Differential cross sections have been measured for nucleon-isobar production and elastic scattering in p−p interactions from 6.2 to 29.7 GeVc in the laboratory angle range 8<θsc<265 mrad. N*' s at 1236, 1410, 1500, 1690, and 2190 MeV were observed. Computer fits to the mass spectra under varying assumptions of resonance and background shapes show that conclusions on t and s dependence are only slightly affected despite typical variations in absolute normalization of ± 35%. Logarithmic t slopes in the small- |t| range are ∼15 (GeVc)−2 for the N*(1410), ∼5 (GeVc)−2 for the N*'s at 1500, 1690, and 2190 MeV, and ∼9 (GeVc)−2 for elastic scattering. Also for the small- |t| data, cross sections for N*'s at 1410, 1500, 1690, and 2190 MeV and for elastic scattering vary only slightly with Pinc consistent with the dominance of Pomeranchuk exchange and with diffraction dissociation. A fit of N*(1690) total cross sections to the form σ∝P−n gives n=0.34±0.06, while for elastic scattering n=0.20±0.05. For the N*(1690) the effective Regge trajectory has the slope αeff′(0)=0.38±0.17. When compared with N* production in π−, K−, and p¯ beams these data also agree with approximate factorization of the Pomeranchuk trajectory. N*(1236) cross sections are consistent with other measurements at similar momenta. For −t>1 (GeVc)−2, elastic scattering cross sections decrease approximately as Pinc−2, and they and N*(1500)− and N*(1690)− production cross sections have t slopes consistent with 1.6 (GeVc)−2.
No description provided.
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We present measurements of the invariant cross section for the inclusive reaction p+p→p+X in the region 0.14<|t|<0.38 GeV2, 100<s<750 GeV2, and 0.80<x<0.93.
The cross sections are fitted by the formula CONST(C=A)*EXP(SLOPE*T)*(1+CO NST(C=B)/SQRT(S)).
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