K. Tittel

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 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.

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.

A high-resolution total absorption spectrometer for simultaneous detection of several high-energy γ-rays

Abstract A large γ-ray total absorption spectrometer is described. It consists of 61 blocks of lead-glass, each one observed by separate photomultipliers. Thin lead converters and wire spark chambers in front of the hodoscope determine the direction of the γ-rays.

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.

Interference between KL → π+π- and KS → π+π- behind a copper regenerator

Abstract The interference between K L → π + π - and K S → π + π - behind a copper regenerator has been observed in a high statistics experiment. The modulus and the argument of the complex ratio ϱ ( p )/ η +- , where ϱ ( p ) is the regeneration amplitude and η +- = A ( K L → π + π - )/ A (K S → π + π - ) has been measured over the momentum interval from 2.0 GeV/ c to 6.0 GeV/ c . The phase of η +- as deduced from this measurement and from the optical model value of arg [ ϱ ( p )] is 49.3° ± 6.8°. The K L K S mass difference has been found to be Δm/ h = (0.555 ± 0.020) × 10 10 sec −1 .

On KL - KS regeneration in copper

Abstract The transmission regeneration amplitude after a thick copper block has been measured. The quantity ∣ƒ(0)− ƒ (0)∣ k varies from 20.0 ± 1.4 mb at 2.75 GeV/ c to 13.6 ± 1.2 mb at 7.25 GeV/ c . Results are in agreement with optical model calculations in which real and imaginary parts of the amplitudes for single nucleon scattering are determined from forward dispersion relations and total cross-sections.

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).

A precision determination of the KL - KS mass difference

Abstract The K L - L S mass difference has been measured to be δm = (0.542 ± 0.006) × 10 10 sec −1 . Combined with K L - L S interference experiments in the π + π − decay channel, the experiment gives an improved value for arg (K L → π + π − /K S → π + π − ).