Proton-proton elastic differential cross sections have been measured for incident laboratory momenta of 600-1800 MeVc and c.m. angles of 5°-90°. The data span, in a single experiment, the intermediate energy region from isotropic differential cross sections at lower energies to the development of a clear diffraction peak at higher energies. Parameters for phenomenological formulations derived from the experimental results are presented.
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The ratio of π+p to pp elastic scattering is found to be smoothly varying over the range −t=0.03 to 0.4 GeV2. It is well fitted by a single exponential, indicating the forward behavior must be quite similar for the two reactions.
ACTUALLY THE DATA ARE THE EXPONENTIAL SLOPE OF THE RATIO OF D(SIG)/DT FOR THE TWO REACTIONS.
A comparison of K±p and p±p elastic scattering is made for incident energy 50 to 175 GeV. Average values of 0.19±0.04 and 0.11±0.02 GeV2 were found for the invariant-momentum-transfer values of the Kp and pp crossover points, respectively.
KP AND PP CROSSOVER POINTS AT -T = 0.19 +- 0.04 AND 0.11 +- 0.02 GEV**2 (AVERAGE VALUES) RESPECTIVELY.
The differential cross sections for the elastic scattering of π+, π−, K+, K−, p, and p¯ on protons have been measured in the t interval -0.04 to -0.75 GeV2 at five momenta: 50, 70, 100, 140, and 175 GeV/c. The t distributions have been parametrized by the quadratic exponential form dσdt=Aexp(B|t|+C|t|2) and the energy dependence has been described in terms of a single-pole Regge model. The pp and K+p diffraction peaks are found to shrink with α′∼0.20 and ∼0.15 GeV−2, respectively. The p¯p diffraction peak is antishrinking while π±p and K−p are relatively energy-independent. Total elastic cross sections are calculated by integrating the differential cross sections. The rapid decline in σel observed at low energies has stopped and all six reactions approach relatively constant values of σel. The ratio of σelσtot approaches a constant value for all six reactions by 100 GeV, consistent with the predictions of the geometric-scaling hypothesis. This ratio is ∼0.18 for pp and p¯p, and ∼0.12-0.14 for π±p and K±p. A crossover is observed between K+p and K−p scattering at |t|∼0.19 GeV2, and between pp and p¯p at |t|∼0.11 GeV2. Inversion of the cross sections into impact-parameter space shows that protons are quite transparent to mesons even in head-on collisions. The probability for a meson to pass through a proton head-on without interaction inelastically is ∼20% while it is only ∼6% for an incident proton or antiproton. Finally, the results are compared with various quark-model predictions.
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We give cross sections for annihilation and non-annihilation reactions in p p interactions at 8.8 GeV. The non-annihilation data are compared with pp data from the same experiment. We compare data on resonance production and on the impact parameter structure of the final states in p p annihilation and non-annihilation and pp interactions. We investigate the charge structure of the 2 π + 2 π − π 0 final state, and find it consistent with a simple quark model.
NORMALIZED TO A TOTAL AP P CROSS SECTION OF 55.9 MB. ANNIHILATION CROSS SECTIONS.
NORMALIZED TO A TOTAL AP P CROSS SECTION OF 55.9 MB. NON-ANNIHILATION CROSS SECTIONS.
NORMALIZED TO A TOTAL P P CROSS SECTION OF 40.0 MB.
The Fermilab hybrid 30-in. bubble-chamber spectrometer was exposed to a tagged 147-GeV/c positive beam containing π+, K+, and p. A sample of 3003 K+p, 19410 pp, and 20745 π+p interactions is used to derive σn, 〈n〉, f2cc, and 〈nc〉D for each beam particle. These values are compared to values obtained at other, mostly lower, beam momenta. The overall dependence of 〈n〉 on Ea, the available center-of-mass energy, for these three reactions as well as π−p and pp interactions has been determined.
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Accelerating polarized protons to 22 GeV/c at the Brookhaven Alternating Gradient Synchro- tron required both extensive hardware modifications and a difficult commissioning process. We had to overcome 45 strong depolarizing resonances to maintain polarization up to 22 GeV/c in this strong-focusing synchrotron. At 18.5 GeV/c we measured the analyzing power A and the spin-spin correlation parameter Ann in large- P⊥2 proton-proton elastic scattering, using the polarized proton beam and a polarized proton target. We also obtained a high-precision measurement of A at P⊥2=0.3 (GeV/c)2 at 13.3 GeV/c. At 18.5 GeV/c we found that Ann=(-2±16)% at P⊥2=4.7 (GeV/c)2, where it was about 60% near 12 GeV at the Argonne Zero Gradient Synchrotron. This sharp change suggests that spin-spin forces may have a strong and unexpected energy dependence at high P⊥2.
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2.2 GeV point taken from Brown et al., PR D31(85) 3017.
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We report results from a measurement of antiproton-proton and proton-proton small-angle elastic scattering at √ s = 24.3 GeV in the range 0.001 ⩽ | t | ⩽ 0.06 (GeV/ c ) 2 . The measurement was performed at the CERN p p Collider by using silicon detectors to observe protons recoiling from a hydrogen cluster-jet target intercepting the stored p and p beams. Fits to the measured differential cross sections yield the ratio of the real to the imaginary part of the forward nuclear scattering amplitude ρ and the nuclear slope parameter b for both p p and pp. We find that the difference Δρ = ρ ( p p ) − ρ( pp ) = 0.031 ± 0.010 agrees with conventional fits and disagrees with the “odderon” fit designed to accommodate the recent UA4 measurement of ρ( p p) at 546 GeV.
Data requested from authors.
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Nuclear slopes fixed to world average.
The analyzing power Ay for p+p elastic scattering at θlab=8.64°±0.07° (θcms=18.1°) and at a bombarding energy of 183.1±0.4 MeV has been determined to be Ay=0.2122±0.0017. The error includes statistics, systematic uncertainties, and the uncertainty in bombarding energy and angle. This measurement represents a calibration standard for polarized beams in this energy range. The absolute scale for the measurement has been obtained by comparison with p+C elastic scattering at the same energy at an angle where Ay is very nearly unity.
Axis error includes +- 0.0/0.0 contribution (?////).
Measurements of the pp spin correlation coefficients Axx, Ayy, and Axz and analyzing power Ay for pp elastic scattering at 197.8 MeV over the angular range 4.5°–17.5° have been carried out. The statistical accuracy is approximately ±0.01 for Amn and ±0.004 for Ay, while the corresponding scale factor uncertainties are 2.4% and 1.3%, respectively. The experiment makes use of a polarized hydrogen gas target internal to a proton storage ring (IUCF Cooler) and a circulating beam of polarized protons. The target polarization (Q=0.79) is switched in sign and in direction (x,y,z) every 2 s by reversing a weak guide field (about 0.3 mT). The forward-scattered protons are detected in two sets of wire chambers and a scintillator, while recoil protons are detected in coincidence with the forward protons by silicon strip detectors placed 5 cm from the proton beam. The background rate from scattering by the walls of the target cell is (0.2±0.2)% of the good event rate. Analysis methods and comparisons with pp potential models and pp partial wave analyses are described.
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