P. Strolin

Small-angle proton-proton elastic scattering at very high energies (460 GeV2 < s < 2900 GeV2)☆

Abstract We have investigated the above processes at the CERN Intersecting Storage Rings (ISR). Results show a marked change of the slope parameter b ( t , s ) = (d/d t ) ln (d σ /d t ) around − t ≈ 0.10 GeV 2 . The s − and t − dependence of b ( t , s ) have been observed over the interval 460 GeV 2 s 2 and 0.02 GeV 2 t 2 .

OBSERVATION OF A DIFFRACTION MINIMUM IN THE PROTON-PROTON ELASTIC SCATTERING AT THE ISR

Abstract We have investigated the pp elastic scattering at the CERN Intersecting Storage Rings (ISR). We report results for centre-of-mass scattering angles between 30 and 100 mrad and for centre-of-mass energies of 23.5,30.7, 44.9 and 53 GeV. The elastic differential cross-section shows a diffraction-like shape with a sharp minimum at about t = −1.4 GeV 2 .

Observation of small angle proton proton elastic scattering at 30 gev and 45 gev center-of-mass energies

Abstract Small angle elastic scattering events have been observed at the CERN Intersecting Storage Rings. Directions of both particles as well as the collision vertex are reconstructed with the help of four sets of spark chambers, two for each of the two arms. The elastic nature of the events is demonstrated by a collinearity requirement. We find values for the (diffraction) slope parameter in disagreement with the simple linear extrapolation of lower energy (Surpukov) data.

Further results on small-angle elastic proton-proton scattering at very high energies☆

Abstract This work extends our previous investigations at the CERN Intersecting Storage Rings, with improved statistics at three different energies, wider angular range and a better control over systematic errors. Values for the (diffraction) shape parameter b are given.

Measurements of the proton-proton total cross section and small angle elastic scattering at ISR energies

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. n nThis 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.

Production of nucleon resonances by single diffraction dissociation at the CERN ISR

The single diffraction dissociation process pp → (pπ+π−)p has been studied at the CERN ISR at √s = 45 GeV and 0.1 < −t < 0.6 GeV2. The reaction is dominated by nucleon resonance production: pp → pN (1520) and pp → pN(1688) with cross-sections (0.25 ± 0.08) mb and (0.56 ± 0.19) mb respectively.

Determination of the proton-proton elastic cross section at 30 GeV center of mass energy

Abstract The absolute luminosity of the CERN Intersecting Storage Rings has been determined by the Van der Meer method. Combining the measurement with small angle proton-proton elastic events, we find σ elastic = (6.8±0.6)mb.

Λ0 polarization in proton-proton interactions at √s = 53 and 62 GeV

Abstract Λ 0 s produced in the inclusive reaction pp → Λ° + X with √s = 53 and 62 GeV at the CERN Intersecting Storage Rings are observed to be polarized along the normal to the production plane. In the ranges of longitudinal and transverse momenta, 15–24 and 0.6-1.4 GeV/ c , respectively, the mean polarization is found to be −(0.357±0.055).

On the decay KL → πoπo

Abstract The ratio | η oo / η +- | between the parameters η oo = A (K L → π o π o )/ A (K S → π o π o ) and η +- = A (K L → π + π - / A (K S → π + π - )) has been measured. The result | η oo / η +- | = 1.0 ± 0.06 is in good agreement with the pr prediction | η oo | = | η +- | of a number of models, for which the CP violation in the 2π channel is independent of the isospin of the final state.

Experimental observation of the angular distribution of charged particles around 90° in the centre of mass produced by proton-proton collisions at very high energies

The angular distribution of charged particles emitted between 47° and 90° in the centre of mass has been measured at the CERN Intersecting Storage Rings with a hodoscope of scintillation counters and for centre-of-mass energies Ecm = 30.2, 44.7 and 52.7 GeV. Data are compatible with distributions of the type 1/σinel × dσ/dΩ(θcm) = A(Ecm) sin−2 θcm. The values of A(Ecm) are about a factor of two greater than the predictions of scaling from data at Ecm=6.0 GeV. The shape of the angular distribution provides evidence for a flat distribution in the “rapidity” variable y = artanh(pL/E).