The total cross sections σT of p, p¯, π±, and K± on hydrogen and deuterium have been measured between 6 and 22 GeVc at intervals of 2GeVc to an accuracy greater than previously reported. The method utilized was a conventional good-geometry transmission experiment with scintillation counters subtending various solid angles at targets of liquid H2 and D2. With the increase in statistical accuracy of the data, it was found that a previously adopted procedure of linearly extrapolating to zero solid angle the partial cross sections measured at finite solid angles was not a sufficiently accurate procedure from which to deduce σT. The particle-neutron cross sections are derived by applying the Glauber screening correction to the difference between the particle-deuteron and particle-proton cross sections. The cross sections σT(π+d) and σT(π−d) are equal at all measured momenta, which confirms the validity of charge symmetry up to 20GeVc. Results are presented showing the variation of cross sections with momentum; evidence is presented for a small but significant decrease in σT(pp) [and σT(pn)] in the momentum region above 12GeVc.
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Measurements of π±p, K±p, pp, and p¯p elastic scattering are presented for incident momenta of 3, 3.65, 5, and 6 GeVc and momentum transfers typically 0.03 to 1.8 GeV2. The angle and momentum of the scattered particle were measured with the Argonne Effective Mass Spectrometer for 300 000 events, yielding 930 cross-section values with an uncertainty in absolute normalization of ±4%. Only the K+ and proton data show any significant change in slope of the forward diffraction peak with incident momentum. The particle-antiparticle crossover positions are consistent with no energy dependence, average values being 0.14 ± 0.03, 0.190 ± 0.006, and 0.162 ± 0.004 GeV2 for π' s, K' s, and protons, respectively; these errors reflect both statistics and the ±1.5% uncertainty in particle-antiparticle relative normalization. Differences between particle and antiparticle cross sections isolate interference terms between amplitudes of opposite C parity in the t channel; these differences indicate that the imaginary part of the odd-C nonflip-helicity amplitude has a J0(r(−t)12) structure for −t<0.8 GeV2, as predicted by strong absorption models. The cross-section differences for K± and proton-antiproton are in qualitative agreement with the predictions of ω universality, the agreement improving with increasing energy. The corresponding quark-model predictions relating the π± and K± differences failed by more than a factor of 2. We have combined our π± cross sections with other data to better determine the πN amplitudes in a model-independent way; results of this analysis are presented.
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We have measured π±p and pp elastic differential cross sections in the range |cosθc.m.|<0.35 for incident momenta from 2 to 9.7 GeV/c for π−p and pp and from 2 to 6.3 GeV/c for π+p. We find that the fixed-c.m.-angle πp differential cross sections cannot be described as simple functions of s. The data are compared to the energy and angular dependence predicted by the constituent model of Gunion, Brodsky, and Blankenbecler.
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Measurements of the total cross section have been performed at the ISR with c.m. energies between 23.5 GeV and 62.5 GeV. Two independent experimental methods have been applied, a measurement of total interaction rate and of small angle elastic scattering. Both experiments give consistent results showing that the total cross section increases by (11.8±1.5) % over the ISR energy range. This experiment has also measured the slope of the forward diffraction peak in elastic scattering at small momentum transfer. The elastic cross section shows the same relative rise as the total cross section, and the ratio λ of elastic to total cross section approaches a constant value of λ =0.178±0.003.
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TOTAL CROSS SECTION FROM (INTERACTION RATE)/(LUMINOSITY). SYSTEMATIC ERROR <0.8 PCT.
TOTAL CROSS SECTION FROM APPLYING THE OPTICAL THEOREM TO SMALL ANGLE ELASTIC SCATTERING EXTRAPOLATED TO T=0.
In the energy region around 380 keV (lab.) and at detection angles near 45° (lab.) the cross section of proton-proton scattering exhibits a deep minimum, since the Coulomb amplitude and the nuclear amplitude almost cancel each other out, resulting in a pronounced deviation from pure Mott scattering. A new set of precise data in the-energy range between 300 and 407 keV was recorded using the accelerator of the IKP Münster by employing a thin gas jet target with an areal density smaller than 8 × 10 14 cm −2 . For the first time p-p scattering near the interference minimum was studied under single scattering conditions using a high quality ion beam (energy spread <40 eV). Since the energy smearing was two orders of magnitude lower than that of the former measurements, a more detailed evaluation of the data was feasible, resulting in differential cross sections near the minimum which are smaller than published before. The measured values cannot be explained by the interference of the Coulomb and the nuclear amplitude alone but suggest the need for vacuum polarization or other additional effects. The position of the minimum was determined to be (382.8 ± 0.1) keV.
Axis error includes +- 0.0/0.0 contribution (?////Random and systematic erros include: adjustment of the ion beam and of the detector system, accelerator energy, counting statistics, correction of the background of the measured peaks, pile-up peaks of the 5.7 deg conters, statisticsof the Monte Carlo simulations, model uncertainty, diameter of the ion beam, po sition of the target, luminosity correction factor K* and the influence of the phase delta_0, fixed in advance, on the angular distribution of the cross section).
A polarized proton beam extracted from SATURNE II was scattered on an unpolarized CH 2 target. The angular distribution of the beam analyzing power A oono was measured at large angles from 1.98 to 2.8 GeV and at 0.80 GeV nominal beam kinetic energy. The same observable was determined at the fixed mean laboratory angle of 13.9° in the same energy range. Both measurements are by-products of an experiment measuring the spin correlation parameter A oon .
Analysing power measurements at a fixed laboratory angle of 13.9 degrees.
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The analyzing power A N of proton-proton, proton-hydrocarbon, and antiproton-hydrocarbon, scattering in the Coulomb-nuclear interference region has been measured using thhe 185 GeV/ c Fermilab polarized-proton and -antiproton beams. The results are found to be consistent with theoretical predictions within statistical uncertainties.
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Data from hydrocarbon target.
Data from hydrocarbon target.
Data are given for the polarization parameter and for the differential cross section in pp elastic scattering at 200 GeV/ c , in the range 0.5 ⪕−t ⪕ 4.0 GeV 2 . The polarization changes sign in the dip region, as already observed at 150 GeV/ c .
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Results are presented from experiment WA7 at the CERN SPS, which has measured the elastic differential cross sections of π ± p, K ± p, p p and pp at incident momen ta of 20, 30 and 50 GeV/ c . The measurements cover the momentum transfer range 0.5 < | t | < 8 (GeV/ c ) 2 , corresponding to c.m. scattering angles between 10° and 50°. The experimental set-up, trigger logic and data analysis are described. The experimental results are compared with existing meson-proton and nucleon-proton data at lower and higher energies covering the medium- and large-| t | region. Some prominent models and their predictions for elastic scattering at WA7 energies and beyond are reviewed, with emphasis on geometrical scaling, factorizing eikonal models, lowest-order QCD and other dynamical exchange-type models. Results for p p two-body annihilation into π − π + and K − K + at 30 and 50 GeV/ c , obtained in parallel with the elastic p p data, are also presented.
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