A description is given of an experiment to study elastic scattering of π ± , K ± and p on protons at c.m. scattering angles from 45° to 100° at incident laboratory momenta 20 GeV/ c and 30 GeV/ c . The corresponding t range is from −6.2 (GeV/ c ) 2 to −28 (GeV/ c ) 2 . There are no previous observations for these reactions in this t range. High intensity and large geometrical acceptance were required in order to measure the low cross sections. The experiment used a double-arm spectrometer. MWPCs were used for reconstruction, and threshold and differential Čerenkov counters for identification. Scintillation counters, Čerenkov counters and a hadron calorimeter were used in the trigger. The trigger logic utilized specially designed matrices and a hard wired microprocessor. The π − p elastic scattering cross sections follow approximately the dimensional counting rule from 3.5 GeV/ c .and up to 30 GeV/ c . The cross sections decrease by seven orders of magnitude in this energy range. The data is compared to quark models. None of these models give a comprehensive description of the results. However, some modifications to these models improve their consistency with the data.
EARLIER RESULTS GIVEN IN 'A'.
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3roton-antiproton elastic scattering at cm energy 540 GeV has been studied in the t range 0.14 ⩽ − t ⩽ 0.26 GeV 2 . The data is well fitted by an exponential form exp( bt ) with b = 13.3 ± 1.5 GeV −2 .
Elastic Differentiaol Cross Section (545 events). DATA REQUESTED 21 FEB 1983. Data read from plot in paper (29 JAN 2015).
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Measurements of the differential elastic cross sections for π − p scattering at incident momenta of 20 and 50 GeV c and π + p at 50 GeV c in the momentum transfer range 0.7 < |t|; < 8.0 ( GeV c ) 2 are presented. The data are compared with various models of elastic scattering.
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Differential cross sections for αα and αp scattering have been measured at √ s =125 and 88 GeV, respectively, in the t range from −0.2 to −0.8 (GeV/ c ) 2 using the Split-Field Magnet detector at the CERN Intersecting Storage Rings. Comparison with theoretical calculations using the Glauber model confirms the importance of including inelastic shadowing effects in very high energy nucleus-nucleus elastic scattering.
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PLAB IS CALCULATED ASSUMING STATIONARY HELIUM TARGET.
We measured the differential cross section for p̄p and pp elastic scattering in the momentum-transfer range 0.01 <| t | < 1.0 GeV 2 at the CERN Intersecting Storage Rings with center-of-mass energy s = 52.8 GeV . Fitting the differential cross section with an exponential [ A exp ( bt )], we found b p p = 13.92 ± 0.59 GeV −2 for | t | < 0.05 GeV 2 , whilst for | t | > 0.09 GeV 2 , b p p = 10.68 ± 0.26 GeV −2 . Using the optical theorem, we obtained for the total cross section σ tot ( p p)= 44.86 ± 0.78 mb and, by integrating the differential cross section, we obtained for the total elastic cross section σ el ( p p) = 7.89 ± 0.28 mb . Calculations of σ tot combining elastic-rate and total-rate measurements are also given. All of these measurements were also performed for pp scattering at the same energy, and the results for both reactions are compared.
NUMERICAL VALUES OF DATA IN FIGURE TAKEN FROM PREPRINT CERN-EP/82-65.
NUMERICAL VALUES OF DATA ON FIGURES TAKEN FROM PREPRINT CERN-EP/82-65.
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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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We measured the elastic scattering of αα at s = 126 GeV and of α p at s = 89 GeV . For αα , the differential cross section d σ /d t has a diffractive pattern minima at | t | = 0.10 and 0.38 GeV 2 . At small | t | = 0.05−0.07 GeV 2 , this cross section behaves like exp[(100 ± 10) t ]. Extrapolating a fit to the data to the optical point, we obtained for the total cross section α tot ( αα ) = 250 ± 50 mb and an integrated elastic cross section σ e1 ( αα ) = 45 ± mb. Another method of estimating σ tot ( αα ), based on measuring the interaction rate, yielded 295 ± 40 mb. For α p, d σ /d t has aminimum at | t | = 0.20 GeV 2 , and for 0.05 < | t | < 0.18 GeV 2 behaves like exp[(41 ± 2) t ]. Extrapolating this slope to | t | = 0, we found σ tot ( α p) = 130 ± 20 and σ e1 ( α p) = 20 ± 4mb. Results on pp elastic scattering at s = 63 GeV agree with previous ISR experiments.
Axis error includes +- 15/15 contribution.
Axis error includes +- 15/15 contribution.
METHOD 1 FOR SIG IS USING OPTICAL THEOREM. METHOD 2 FOR SIG IS BASED ON THE MEASURED LUMINOSITY-MONITOR CROSS SECTIONS.
None
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The mass and momentum transfer spectra of the charged K K system produced in the reaction π ± p→K s 0 K ± p are analyzed. The data have been collected at the CERN SPS with the Geneva-Lausanne two-arm, non-magnetic spectrometer at 30 and 50 GeV/ c incident momenta. The general features of the reactions at these energies and the results of partial-wave analyses of the two kaon system are presented. The channel is dominated by the diffractive production of even spin resonances. The spin 4 recurrence of the A 2 (1320) is clearly observed at 2040 MeV ( Γ =380 MeV. A new resonance is observed with a mass M =2450MeV and a width Γ =400 MeV; the quantum numbers of this state are found to be I G ( J PC )=1 −(6 ++ ) . The analysis also shows the decay of the decay of the meson ϱ′(1600) through the K K channel at both energies. The production amplitudes are determined both as a function of the K K effective mass and of the momentum transfer. Isoscalar natural parity exchange is dominant. The energy dependence between 10 and 50 GeV/ c is shown to be well described by a Regge pole model based on the f-dominated pomeron hypothesis. We compare the production mechanisms of the 2 + resonances A 2 (1320) and K ∗ (1430). Finally, we estimate the K K branching ratios of the spin 4 A 2 (2040) and spin 6 A 2 (2450) resonances.
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D(SIG)/DT FOR 50 GEV IN RESONANCE REGIONS.
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The reactions K ± p→K s 0 π ± p are studied at 30 and 50 GeV/ c . Data for these reactions were obtained using the Geneva-Lausanne spectrometer whose main characteristics are: (i) large forward acceptance; (ii) high-resolution time-of-flight for recoil proton momentum measurement; (iii) high data-taking rate and on-line pattern recognition. The K ∗ (1 − ), K ∗ (2 + ), K ∗ (3 − ) and K ∗ (4 + ) resonance parameters and production cross sections are determined. The K π production amplitudes are calculated both as a function of the K π mass and of the momentum transfer. Isoscalar natural parity exchange (NPE) is dominant. The NPE amplitudes are decomposed into pomeron- f-, ω-exchange contributions, and their energy dependence between 10 and 50 GeV/ c is shown to be well-described by a Regge pole model based on the f-dominated pomeron hypothesis.
CORRECTED TO INCLUDE BW TAILS AND THE FRACTION OF EVENTS OUTSIDE THE T-ACCEPTANCE OF THE SPECTROMETER.
FITS OF THE FORM -A*TP*EXP(BTP) ARE MADE BY THE AUTHORS AND THE VALUES OF A AND B ARE GIVEN HERE. MASS REGIONS OF THE FIT ARE:-. K*(890) 0.84 < M <0.94 GEV. K*(1430) 1.36 < M <1.5 GEV. K*(1780) 1.68 < M <1.88 GEV.
FITS OF FORM -A*TP*EXP(BTP) ARE MADE BY THE AUTHORS AND THE VALUES OF A AND B ARE GIVEN HERE. MASS REGIONS OF THE FIT ARE:-. K*(890) 0.84 < M <0.94 GEV. K*(1430) 1.36 < M <1.5 GEV. K*(1780) 1.68 < M <1.88 GEV.
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