G. Paternoster

Measurement of elastic scattering in antiproton-proton collisions at 52.8 GeV centre-of-mass energy

We measured the differential cross section for pp and pp elastic scattering in the momentum-transfer range 0.01 0.09 GeV2, bpp = 10.68 ± 0.26 GeV−2. Using the optical theorem, we obtained for the total cross section σtot(pp)= 44.86 ± 0.78 mb and, by integrating the differential cross section, we obtained for the total elastic cross section σel(pp) = 7.89 ± 0.28 mb. Calculations of σtot 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.

Precise measurements of proton-antiproton and proton-proton total cross sections at the CERN intersecting storage rings

Abstract A detailed account is given of high-precision measurements of the total hadronic cross sections of proton-antiproton and proton-proton interactions at centre-of-mass energies of 30.6, 52.8 and 62.7 GeV. The experiment was performed at the CERN Intersecting Storage Rings (ISR) using the total interaction-rate method, in which additive correction terms for trigger losses were held to less than 6% of the final result. An experimental determination of the vertical beam-displacement scale permitted luminosity-monitor calibrations to be made with high intrinsic accuracy. The overall precision (systematic and statistical errors combined) achieved in the total cross sections was ± 1.1% for proton-antiproton reactions and 0.7% for proton-proton reactions. In the proton-proton case the measurement was the most precise such measurement made at the ISR.

Measurements of elastic scattering in alpha-alpha and alpha-proton collisions at the CERN intersecting storage rings

Abstract 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 | 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.

Measurement of the antiproton-proton total cross section and elastic scattering at the CERN intersecting storage rings

Abstract We measured the total cross section for p p scattering at √s = 53 GeV at the CERN ISR. The method was based on the measurement of the total interaction rate and of the ISR luminosity. The result obtained, σtot = 44.1 ± 2.0 mb, suggests that σ tot ( p p) starts increasing at ISR energies. A measurement of the p p differential cross section was also performed: the results show a change in the slope at |t| ≈ 0.1 GeV2, similar to that observed in pp scattering.

Evidence of a rise in the antiproton-proton total cross section at the CERN intersecting storage rings

Abstract We measured the total cross section for p p scattering at s = 52.8 GeV at the CERN ISR, using the direct, total-rate method. The result obtained, σ tot ( p p ) = 44.70 ± 0.53 mb , shows that, in common with σtot(pp), this cross section also starts to rise in the ISR energy range. We remeasured the total cross section for pp scattering at the same energy, obtaining σtot(pp) = 43.26 ± 0.33 mb, and found for the difference, Δσ tot = σ tot ( p p ) − σ tot ( pp ) , a value of 1.44±0.45 mb.

Total, elastic, and inclusive single-diffractive cross sections in alpha-alpha collisions at the cern intersecting storage rings

Abstract We present measurements of the total interaction cross section and of the single-diffractive dissociation cross section in αα collisions at √ s = 126 GeV. The result obtained for the total cross section, σ tot = (315±18) mb, is a substantial improvement on the precision of earlier measurements. Earlier elastic data were re-analysed, incorporating, through the optical theorem, the present σ tot measurement, resulting in improved determinations of the forward slope, b − t = (87±4) GeV −2 , and of the integrated elastic cross section, σ el = (58±6) mb. The single-diffractive differential cross section falls exponentially with momentum transfer at small values of t with a slope b sd = (19.3 ± 0.6) GeV −2 . The integrated single-diffractive cross section is σ sd = (16.6±2.5) mb. The topology of charged tracks resulting from the disintegration of the α in single-diffractive events reveals a two-component distribution. The cross section data are compared with multiple-scattering models.

Observation of double-Pomeron exchange in alpha-alpha collisions at the CERN intersecting storage rings

AbstractWe observed the process αα→ααX in which the α′s were emitted uncorrelated in the forward direction and the charged component of the clusterX was confined to a limited portion (|η|≲2) of the central region. We identified such reactions as being due to double-Pomeron exchange, for which we found a cross-section of (720±140)μb. The raw mean charged multiplicity of the clusterX was found to be 6.76±0.07 with a dispersionD=4.8. The measurements were performed at the CERN ISR at a centre-of-mass energy of

An upper limit for the radiative decay width of the J/ψ resonance into η′(958)+γ

\sqrt s = 126