H. Dibon

Measurements of Elastic Proton Proton Scattering at Large Momentum Transfer at the CERN Intersecting Storage Rings

Abstract Final results of our measurements of elastic proton-proton scattering at the CERN Intersecting Storage Rings (ISR) for c.m. energies √ s from 23 to 63 GeV and momentum transfers | t | from 0.8 to 10 GeV 2 are presented. Absolute differential cross sections have been obtained using the split-field magnet detector facility (SFM) at the five standard energies for integrated luminosities ranging from 0.3 to 4.9 (pb) −1 . The rising total cross section is found to define a scale for diffractive phenomena near the forward peak, including the position of the diffraction minimum near t = −1.4 GeV 2 . The cross section at the minimum is strongly energy dependent, approximately as the ratio of the real to imaginary part of the scattering amplitude in the forward direction. The phase of the scattering amplitude is found to change sign near the minimum. The component of diffraction scattering beyond the second maximum has a much weaker t -dependence than expected in simple eikonal or constituent pictures connecting this region to the forward peak. A further break in slope is observed near t = −6 GeV 2 . There is no evidence for another minimum for t values up to 10 GeV 2 .

Experimental results on large angle elastic pp scattering at the CERN ISR

Abstract New experimental results are presented on proton-proton elastic scattering at centre-of-mass energies s =23 GeV and s =62 GeV . The data are obtained using the Split Field Magnet detector at the CERN Intersecting Storage Rings. The absolute differential cross-sections show an energy-dependent behaviour. The position of the diffraction minimum changes from t=(−1.44±0.02)GeV2 at 23 GeV to (−1.26±0.03)GeV2 at 62 GeV. The cross-section at the second maximum is increasing with s . The connection of these observations with the hypothesis of “geometrical scaling” is discussed.

Rapidity correlations in inclusive two-particle production at storage ring energies

Abstract Inclusive two-particle production in the reaction pp → γ + ch + (anything) has been measured at the CERN ISR for four energies ( ✓s = 23,30.5,45, and 53 GeV ) at two production angles of the charged particles (ch) and the eight production angles of the γ-rays. The rapidity correlation of the two particles is weak and of short range. The peak correlation is σ inel ( d 2 σ γ ch d σ γ d σ ch ) − 1 = 0.62 ± 0.08 , the correlation range 〈yγ − ych〉 = 1.17 ± 0.05, independently of s. The φ correlation extends over a wide gap in rapidity; its strength is increasing with increasing transverse momentum.

Experimental Results on Diffractive One Pion Production at the CERN ISR

New experimental results are reported on diffractive dissociation of protons into (nπ+) in proton-proton collisions at a centre-of-mass energy of s = 45 GeV. The data were obtained using the Split-Field-Magnet detector at the CERN Intersecting Storage Rings. We have searched for resonance contributions and found peaks at mass values of 1.5 GeV, 1.65 GeV, and 2.1 GeV. A dip in dσdt is observed at low t and low mass; it is most pronounced for events with neutrons emitted at 90° in the Gottfried-Jackson frame. The correlation between mass and slope depends strongly on θJ. The cross section of the channel pp → pnπ+ is 400 ± 110 μb at s = 45 GeV, giving an energy dependence of s−0.30±0.07 for isospin exchange zero in this channel.

Transverse momentum spectra of charged particles in pp collisions at s=630 GeV

Abstract We have analysed a sample of 2.36 million minimum bias events produced in p p collisions at s =630 GeV in the UA1 experiment at the CERN collider. We have studied the production of charged particles with transverse momenta (pT) up to 25 GeV/c. The results are in agreement with QCD predictions. The rise of 〈pT〉 with charged particle multiplicity may be related to changing production of low pT particles.

Transverse momentum spectra of charged particles in

Abstract We have analysed a sample of 2.36 million minimum bias events produced in p p collisions at s =630 GeV in the UA1 experiment at the CERN collider. We have studied the production of charged particles with transverse momenta (pT) up to 25 GeV/c. The results are in agreement with QCD predictions. The rise of 〈pT〉 with charged particle multiplicity may be related to changing production of low pT particles.

p \bar{p}

Abstract A determination of branching ratios for D meson decays into all charged particle final states is reported. The values obtained: (D± → K∓π±π±/all D±) = (14 ± 6)% and ( D 0/D0 → K±π∓π+π−/all D 0/D0) = (10 ± 4)%, are higher than those currently accepted. This result, if confirmed, implies a corresponding reduction in the accepted values for some total cross section measurements. Revised inclusive cross sections for D meson production in the forward hemisphere in π−p and pp interactions at 360 GeV/c, are presented.

collisions at

Abstract Higher order Bose-Einstein correlations up to fifth order, of particles produced in proton-antiproton collisions, are presented using UA1 data at √ s =630 and 900 GeV. The results are compared with theoretical calculations to investigate the primary assumptions for the parametrization of the correlation functions.

\sqrt{s}

Abstract We have analysed a sample of 2.36 million minimum bias events produced in p p collisions at s =630 GeV in the UA1 experiment at the CERN Sp p S collider. We have studied the production of K S 0 , Λ and Λ particles with transverse momenta ( p t ) up to 7 GeV/c and K ± up to 2 GeV/c. The kaon data are compared with a recent QCD prediction and are found to be in good agreement. The p t > for K S 0 , Λ and Λ is seen to increase as a function of the charged particle multiplicity and is compared with charged particle production.

= 630-GeV

The trigger used for the collection of the samples of K0→π0π0 decays in the NA48 experiment at CERN uses a novel pipeline design in order to satisfy the demanding specifications of a high rate kaon beam. The trigger algorithms, architecture and performance are described.