Multiplicities in84Kr interactions in emulsion at 800–950 MeV/nucleon

Inelastic interactions induced by⁸⁴Kr nuclei at 800–950 MeV/nucleon have been studied using a high angular resolution emulsion detector. Data on multiplicities of the produced particles, projectile and target fragments are shown. Comparisons with cascade calculations have been performed.We thank to Swedish Research Council for Natural Sciences for the financial support. Scanning and measurements performed by E.G. Broomé and V. Kopljar are acknowledged.     

A Comparative study of p-Em and C12-Em interactions at 4·5 GeV/c per nucleon

In this paper we present a comparative study of inelastic interactions of C¹²-Em and p-Em at 4·5 GeV/c per nucleon. The multiplicity distributions and their correlations have been studied. The results show a strong correlation of n _s onn _h in the case of C¹²-Em but not in the case of p-Em. It is also shown that the n _s increases with the increase of the projectile mass. The angular distribution of the target fragments in C¹²-Em shows a massive forward collimation. Comparison is also made in the pseudorapidity distribution of both C¹²-Em and p-Em, the result shows many interesting features.     

The temperatures of protons andπ − mesons in central nucleus-nucleus interactions at a momentum of 4.5 GeV/c per incident nucleon

An estimate of the temperature of protons and ^– mesons in central He–Li, He–C, C–C, C–Ne, C–Cu, C–Pb, O–Pb, Mg–Mg interactions is presented. The results indicate an increase of the proton temperature with increasing mass numbers of projectile and target nuclei (A _p ,A _T ) fromT _p =(118±3) MeV for He–Li toT _p =(141±2) MeV for C–Pb. The temperature of ^– mesons does not depend onA _P ,A _T andT 95 MeV. A satisfactory fit for ^– mesons in C–Cu, C–Pb, O–Pb, Mg–Mg collisions can be achieved by using a form involving two temperatures,T ₁ andT ₂. The relative yield of the high temperature component (T ₂) is 24% for C–Cu, C–Pb, and Mg–Mg interactions. The observed results forT _P in C–Ne, C–Cu and C–Pb collisions are consistent with the prediction of the thermodynamic hagedorn model.     

Mechanism of pion production in αp scattering at 1 GeV/nucleon

An analysis of the experimental data on one-pion and two-pion production in the p(??, ????)X reaction studied in a semi-exclusive experiment at an energy of E _?? = 4.2 GeV has been performed. The obtained results demonstrate that the inelastic ??-particle scattering on the proton at the energy of the experiment proceeds either through excitation and decay of the ?? resonance in the projectile ?? particle, or through excitation in the target proton of the Roper resonance, which decays into a nucleon and a pion, or a nucleon and a ?? meson??a system of two pions in the isospin I = 0, S-wave state.     

Evidence of intermittent fluctuation of target fragments in ^84Kr-AgBr interactions at 1.7 A GeV

Intermittency and fractal behaviour have been studied of emission spectra of target associated fragments from ^84Kr-AgBr interactions at 1.7 A GeV in emission angle space and azimuthal angle space separately. The intermittent behaviour is observed in the two spaces separately. Prom the intermittency exponent, the anomalous fractal dimension dq is calculated and the variation of dq with the order q is investigated. It is found that the anomalous dimensions are found to increase with the order of moments q, thereby indicating the relation of multifractality to production mechanism of target associated fragments.     

Study of compound particle production in ~（84）Kr-emulsion interactions at 1.7 A GeV

The characteristics of compound particle multiplicity distribution and multiplicity correlations between the compound particle and the grey particle, black particle, shower particle and heavily ionized track particle are investigated in this paper. It is found that the average multiplicities of the grey particle, black particle, shower particle and heavily ionized track particle increase with an increase in the number of compound particles, which can be explained by the impact geometrical model. The compound multiplicity distribution is observed to obey a Koba-Nielson-Olesen (KNO) type of scaling law.     

Decay asymmetry of the K− π+ system in K− nucleon interactions at 3 GeV/c

The decay asymmetry of the K⁻π⁺ system was measured in two reactions and found to be equal to that observed for K⁺π⁻ systems, in agreement with its intepretation as an S waves effect in Kπ scattering.     

Analyzing the features of π− mesons and protons from AC interactions at a momentum of p=4.2 GeV/c per projectile nucleon on the basis of the FRITIOF model

The mean multiplicities of π^? mesons and protons originating from pC, dC, αC, and CC interactions at a momentum of p=4.2 GeV/c per projectile nucleon and the distributions of these particles in kinematical variables are presented. These experimental distributions are compared with the corresponding predictions obtained on the basis of the FRITIOF model. It is shown that the FRITIOF version used in the present analysis describes satisfactorily our experimental data.     

Characteristics of Λ andK 0 particles produced in central nucleus nucleus collisions at a 4.5 GeV/c momentum per incident nucleon

Data on Λ's andK ⁰'s, produced in central nucleus-nucleus collisions (C?C, C?Ne, O?Ne, C?Cu, C?Zr, C?Pb, O?Pb) at a 4.5 GeV/c momentum per incident nucleon obtained in the streamer chamber spectrometer SKM-200, are presented. Multiplicities, transverse momenta, rapidities and other characteristics are considered and compared with those for inelastic He?Li interactions. The polarization of Λ's was found to be consistent with zero. The upper limit of \(\bar \Lambda /\Lambda \) production ratio was estimated to be ≤10^?2 with a 90% confidence level. The results are compared with data of other experiments and some model calculations.     

Ψ′ and J/Ψ production in p-W,p-U and S-U interactions at 200 GeV/nucleon

Ψ′ and J/Ψ yields are compared in p-W, p-U and S-U interactions at 200 GeV/nucleon. Their ratio decreases from proton-t to sulphur-induced reactions. It also decreases in sulphur-induced reactions from peripheral to central collisions. This result could indicate that the Ψ′ and J/Ψ suppression mechanisms have different origins in p- and S-induced reactions.     

Angular dependence of Bose-Einstein correlations in interactions of π+ andK + mesons with protons and nuclei at 250 GeV/c

The angular dependence of Bose-Einstein correlations is studied in interactions of ⁺ andK ⁺ mesons with protons and nuclei at 250 GeV/c. The pion source is found to be elongated along the interaction axis in the c.m.s., with the ratioa between transverse and longitudinal dimension equal to 0.55±0.06 for the case of proton, 0.53±0.13 for the case ofAl and 0.33±0.21 for the case ofAu target. For meson-proton interactions, indication for an increase of the elongation is found with increasing event multiplicity, pair momentum and particle transverse momentum.Now at UIA, Wilrijk, Belgium     

Observation of ω1− production in K−p interactions at 11 GeV/c

Clear evidence is presented for the production of an Ω¹⁻ resonance of mass 2253±13 MeV/c² and width 81±38 MeV/c² in K⁻p interactions at 11 GeV/c. The state is observed in the Ξ (1530)K̄ decay mode, and the corresponding inclusive cross section is estimated to be 630±180 nb. Comparisons are made with theoretical predictions and with similar states observed inhyperon beam induced data.     

Investigation of charged-hadron production in proton–nucleus interactions at the energy of 50 GeV

Cross sections for the production of high-transverse-momentum charged hadrons in proton–nucleus interactions at the incident-proton energy of 50 GeV were measured with the aid of the FODS double-arm spectrometer. Single hadrons (charged pions and protons) emitted at a c.m. angle of about 90° and high-effective-mass pairs of hadrons flying apart at a c.m. angle of 180° were detected simultaneously. Results on the production of single hadrons are presented.     

Intermittency of Target Fragments in ^16O-AgBr Collisions at 4.5 A GeV/c

We report the angular distributions of grey and black particles produced in ^16O-AgBr interactions at 4.5 A GeV/c in nuclear emulsion. Intermittency and fractal behaviour are studied for emission spectra of target associated grey and black particles. Intermittent behaviour is observed for both grey and black particles. In both the cases, anomalous dimensions are seen to increase linearly with the order of moments, thereby indicating the association of multifractility with production mechanism of both grey and black particles.     

Two-pion decay of the P 11(1440) resonance excited in αp Scattering at 1 GeV/nucleon

Semiexclusive measurements of the two-pion production reaction p(α, α′)pππ have been carried out at an energy of E _α = 4.2 GeV at the Saturne-II (Saclay) accelerator with the SPES4-π installation. The two-pion production reaction was investigated by simultaneous registration of the scattered α particle and the secondary proton. The obtained results show that the two-pion decay of the P ₁₁(1440) resonance excited in the target proton in this reaction proceeds predominantly with emission of two pions in the isospin I = 0, S-wave state. The text was submitted by the authors in English. the SPES4-π Collaboration     

Study of four-prong events in π+p interactions at 3.5 GeV/c

The non-strange four-prong events of π⁺p interactions at 3.5 GeV/c are studied. Cross sections are calculated for all resonance productions in the channels π⁺p → pπ⁺π⁺π⁻ (σ_T = 3.18 ± 0.13 mb) and π⁺p → pπ⁺π⁺π⁻π^o (σ_T = 4.03 ± 0.16 mb). The dominant two body reactions Δ⁺⁺ϱ^o and Δ⁺⁺ ω^o are investigated in detail, and production and decay distributions are presented as well as joint decay density matrix elements and joint correlation terms. The Δ⁺⁺ϱ^o reaction is compared to predictions of OPE with absorption and the Δ⁺⁺ω^o is compared to rho-exchange with sharp cutoff.     

Systematic study of multiparticle production in nucleus–nucleus interactions at 14.6 A GeV

An experimental analysis of 855 events induced by 14.6 A GeV ²⁸Si in nuclear emulsion is presented. Mean multiplicities of charged secondary particles produced in the nuclear interactions are studied and compared with the results from the other experiments for the same projectile at 3.7 A GeV as well as data for proton at similar energy (14 GeV). An analysis of pseudorapidity densities of target fragments (black and grey particles) is also performed. The behaviour of the KNO scaling law of the multiplicity distribution for shower particles has been examined. In order to accumulate knowledge about the intermittent behaviour of shower particles, the scaled factorial moments (SFMs) are computed in η-space and ?-space for a set of data in the ²⁸Si–AgBr events. Furthermore, validity of limiting fragmentation of shower particles produced in central collision events induced by ²⁸Si-emulsion interactions has been tested. A crude estimation for the energy density of the nuclear matter formed in the central collision events at our energy has been examined.     

Inclusive production of vector mesons in π+ p interactions at 250 GeV/c

We report on a study of ρ⁰, ρ⁺, ω, \(\bar K^{*0} (892)\) andK ^*0 (892) inclusive production in π⁺ p interactions at 250 GeV/c, for ρ⁺, \(\bar K^{*0} (892)\) for the first time in a π⁺ p experiment. The data are compared withK ⁺ p data in the same experiment, with results of other experiments and with quark-parton models. Interesting differences are found between ρ^+,0 and ω production.     

Momentum spectra of secondary particles in (π−, N) interactions at 7 GeV

The experimental momentum spectra of secondary π-mesons and protons from the (π⁻, N)-interactions at 7 GeV in the laboratory system are compared with the formula given by Aly, Kaplon and Shen [6]. The fit of the linear-exponential distribution, of Maxwell-Boltzmann's distribution and for Planck's law was determined for the experimental histograms of the transverse momenta for the same events. The obtained results are discussed at the end of this paper.