W. Wójcik

General characteristics of particle production in 16 GeV/cπ−p interactions

Abstract Partial cross sections are presented for the various topologies and the various reaction channels in 16 GeV/ c π − p interactions. Their energy dependence is discussed. The distributions of events as a function of the squared four-momentum transfer are presented, as well as the transverse and c.m. longitudinal momenta distributions. The predictions of the Chan, Łoskiewicz and Allison model describe some of the gross features of these experimental results, but important disagreements are found, mostly in the low multiplicity channels.

Charged and neutral particle multiplicity in π−p and π−n interactions at 40 GeV/c

Abstract Data on the multiplicity of charged particles and π 0 mesons in π − p and π − n interactions are presented and compared to various models. The average π 0 multiplicity tends to increase with increasing number of charged particles.

Multiplicity distribution and nuclear effects in π−d interactions at 21 GeV/c

Results on the charged multiplicity distribution in π−d interactions at 21 GeV/c are presented. The effects due to the two-nucleon structure of the deuteron target are analysed and the contribution of double scattering processes is estimated as a function of charged multiplicity. The evidence against simple cascade models is discussed.

Three- and four-pion angular correlations in high-multiplicity πp interactions

Abstract A new set of parameters is introduced to describe charge dependence of three- and four-pion correlations. An effect similar to the GGLP effect observed for pion pairs, but stronger, is found for three- and four-pion systems. This effect, however, can be interpreted as a reflection of the GGLP effect.

On the dominant role of the baryon variables in the description of high-multiplicity interactions at high energy

Abstract It is shown that in the reactions: π + +p→p+5 π and π + +p→p+6 π at 8 GeV/ c the secondary protons determine the general features of the pion distributions.

Some characteristics of inclusive reactions π-p → π± + ... and π-n → π± + ... at p = 40 GeV/c

Abstract Data on inclusive reactions π − p → π ± + … and π − n → π ± + … at 40 GeV/ c are presented. Inclusive cross sections of the reactions π − p → π ± + … at x = 0 normalized to the inelastic cross section coincide with the ISR results for pp interactions at 500 – 1500 GeV. A similar result has been obtained for the inclusive process π − p → γ + … as well.

Longitudinal phase space analysis of six-body events: Aachen-Berlin-Bonn-CERN-Cracow-Dubna-Durham-Heidelberg-Nijmegen-Paris (E.P.)-Saclay-Torino-Warsaw Collaboration

Abstract The reaction πp → p5π has been studied in six-prong events of π+p interactions at 5, 8 and 16 GeV/c and of π−p interactions at 5, 11 and 16 GeV/c, using the longitudinal phase space (LPS) technique. The energy dependence of cross sections in LPS sectors was found to depend on the charge and the baryon number “exchanged” between the primary pion and the group of forward-going secondary particles. Selection of certain LPS sectors greatly improves the separation of resonances from background. A strong correlation has been observed between fast forward beam-like pions and protons slow in the c.m.s. A simple interpretation of this observation is discussed.

Multiplicity of charged particles π− interactions on nuclei at 40 GeV/c

Multiparticle production in π−-nucleus interactions at 40 GeV/c (Fifth Joint CERN-Serpukhov Experiment) has been studied using a spark-chamber technique at the Serpukhov accelerator. The mean multiplicities, the pseudorapidity distributions and the dispersion of the multiplicity distributions of charged particles produced on C, Al, Cu and Pb targets are presented. The data have been analysed, both subtracting and including secondary protons with p 3.4 the average multiplicity is nearly independent of the size (ν) of the target nucleus, while it increases for η 4) the mean multiplicity on nuclei is smaller than the mean multiplicity on hydrogen. The dependence upon ν in the target fragmentation region is stronger when the emitted protons are included in the pseudorapidity distributions of the secondary particles. The dispersion of the multiplicity distributions for the different nuclear targets versus the mean multiplicity shows the same slope as found by the world statistics on hydrogen and by other experiments on nuclei at different energies. The results are compared with the predictions of the coherent tube model and with the soft hadron-nucleus collision model.

Proton-proton and pion-proton inelastic collisions and the proton and pion form factors

Abstract A model of proton-proton inelastic collisions at high energies is proposed. It assumes that the amplitude for a collision in which n secondary particles are produced is a product of n form factors identical with the charge form factor of the proton. The predictions of the model are compared with the experimental data. The main characteristics of the experimental distributions of secondary particles are well reproduced by the model. The experimental data on high-energy pion-proton collisions are also compared with the prediction of the model.

Two classes of reaction mechanism in π± interactions at 8 to 23 GeV/c

Abstract The longitudinal correlations between the proton and the most forwardly produced beam-like pion ( π f ) are studied in the reactions π ± + p → π f ± + p + anything at 8, 16 and 23 GeV/c. Maxima are observed in the two-particle inclusive cross sections which can be interpreted as resulting mainly from (a) diffractive processes and (b) mechanisms of central particle production. The average multiplicity of final state particles is lower and increases more slowly with increasing energy for diffractive processes than for the central production.