Fluctuations of multiplicities in rapidity windows in sulphur-sulphur collisions at 200A GeV

Multiplicity distributions and their second moments fornegatively charged particles produced in³²S-S central and minimum bias interactions at 200A GeV are studied in various rapidity intervals. Fritiof and Venus models mostly describe the dependence of second moments on rapidity intervals in minimum bias interactions, but not in central collisions. For central collisions the behaviour of second moments might indicate enhanced multiplicity fluctuations.     

Recent results on particle production from silicon emulsion interactions at 14.6A GeV

A comparative study of results obtained from the interactions of 14.6A GeV ²⁸Si in nuclear emulsion is presented. In this work the experimental data serve as one of the decisive signature of quark–gluon plasma formation. The data for 200 and 400 proton-emulsion interactions are used to investigate the assumption which consider interaction of ²⁸Si-Em at 14.6A GeV is such that for a proton with total energy corresponding to that for effective number of interacting nucleons (12.6×14.6=175) or as a proton having the total energy of ²⁸Si (i.e., 28×14.6=409 GeV). It is also shown that the relativistic quantum molecular dynamics model nicely predicts the multiplicities and correlations of shower and grey particles in the interactions of ²⁸Si with emulsion nuclei at 14.6A GeV.     

Topological cross sections and charged particle multiplicities inpp interactions at 360 GeV/c

Using data obtained with EHS equipped with the Rapid Cycling Bubble Chamber (RCBC) exposed to a proton beam of 360 GeV/c, we calculate topological cross sections. We present in great detail the procedure and the techniques used to correct raw data. Finally, we give multiplicity moments and multiplicity correlations and we compare the values obtained in our experiment, together with data at other energies, with different models.     

A systematic study of the energy independent behaviour of the fragmentation regions in16O-Em interactions from 3.7 to 200A GeV

The scaling behaviour in the fragmentation regions is investigated for¹⁶O-Em interactions from 3.7 to 200A GeV. It is found that in both the projectile- and the target-fragmentation regions, the multiplicity and pseudo-rapidity distributions as well as the two-particle pseudo-rapidity correlations are independent of incident energy. The intermittency indices at 14.6, 60 and 200A GeV are the same within the experimental errors, indicating that the limiting fragmentation hypothesis works with regard to dynamical as well as statistical fluctuations.     

28Si(32S) fragmentation at 3.7 A, 14.6 A and 200 A GeV

The fragmentation topology of²⁸Si at 3.7A GeV and 14.6A GeV and³²S at 200A GeV in reactions with emulsion nuclei is presented. The fragmentation cross sections are very similar at all three energies. A statistical percolation model can qualitatively describe the data forZ 6. The He production is underestimated and the 3 Z 5 fragments overestimated by this model.     

Associated average charged particle multiplicities in K+p interactions at 32 GeV/c

The average charged particle multiplicities, 〈n_R(M_X²)〉, in the reactions K⁺p → π^?X and K⁺p → K⁰X at 32 GeV/c are studied as functions of the mass squared M_X² of the “associated” system X. A comparison with the corresponding results obtained at lower incident momenta is presented.     

Fragmentation in ^16 O-emulsion interactions at 3.7 A GeV

The topology of ¹⁶O fragmentation at 3.7 A GeV in reactions with emulsion nuclei is presented. The multiplicity distributions of projectile fragments,charged secondaries and their dependences on the projectile residues are discussed.     

Study of multiparticle spikes in central 4.5A GeV/c C-Cu collisions

An analysis of local fluctuations, or spikes, is performed for charged particles produced in central C-Cu collisions at 4.5 GeV/c/nucleon. The distributions of spike centers and the maximum density distributions are investigated for different narrow pseudorapidity windows to search for multiparticle dynamical correlations. Two peaks over statistical background are observed in the spike-center distributions with the structure similar to that expected from the coherent gluon radiation model and recently found in hadronic interactions. The dynamical contribution to maximum density fluctuations is obtained to be hidden by statistical correlations, although behavior of the distributions shows qualitative agreement with that from the one-dimensional intermittency model. The observed features of the two different approaches, coherent vs. stochastic, to the formation of the local dynamical fluctuations are discussed.     

Multiplicity and angular distributions of charged particles in interactions of Fe in emulsion at 2.5A GeV/c

Data are presented on multiplicity and angular distributions of charged secondary particles from inelastic interactions of ⁵⁶Fe in emulsion at 2.5A GeV/c. Comparisons with data, at nearby the same incident momentum per nucleon from p-A, ¹⁴N-A, ¹⁶O-A and ⁴⁰Ar-A collisions are performed in order to trace the dependence on projectile and target mass. Furthermore, the ⁵⁶Fe data are compared with the results from a cascade-evaporation model. This comparison shows some significant deviations between the model and the data which are not observed for light ion induced collisions.     

Multiplicity and pseudorapidity distributions of charged particles from32S induced heavy ion interactions at 200A GeV

Multiplicity and pseudorapidity distributions have been measured for³²S+Al, Cu, Ag and Au at 200A GeV. The widths of the pseudorapidity distributions increase from central to peripheral collisions. The main contribution is assumed to come from the increasing fraction of charged particles stemming from the fragmentation of the target for peripheral collisions as compared to central collisions. On the average 170–180 charged particles per unit of pseudorapidity are attained for the most central³²S+Au events at the maximum of the distribution. The target dependence of the yield of charged particles for central collisions is investigated. In the target rapidity region the yield is directly proportional to the target mass. The transverse energy per charged particle has been studied as a function of centrality and pseudorapidity. The experimental results are compared to the results from the Monte-Carlo model VENUS 3.11 which includes rescattering among secondaries. A comparison between different centrality triggers is made.     

Leading particle distributions in 200 GeV/c p+A interactions

Distributions of the leading positive particle have been measured in collisions of a 200 GeV/c proton beam with hydrogen, Mg, Ag and Au targets using the FNAL Hybrid Spectrometer. Estimates of the rapidity loss of the projectile have been obtained as a function of the target mass, the multiplicity of negative particles and the number of recoil protons. We obtained a lower limit of the rapidity loss of 2.0±0.2 for central p+Au collisions. The impact parameter dependence of the momenta of the first few leading particles has also been investigated with important implications to estimates of energy densities obtained in central collisions.     

Forward and backward multiplicities inK − p interactions at 110 GeV/c

Multiplicity distributions and correlations between charged particles in the forward and back-ward c.m. hemispheres are studied inK ^?p interactions at 110 GeV/c and compared with other data on mesonnucleon scattering. The interpretation in terms of a simple quark-parton picture assuming that the forward multiplicity is dominated by quark fragmentation and the backward multiplicity by diquark fragmentation is supported by the experimental fact that the forward and the backward mean multiplicities are approximately equal to half of thee ⁺ e ^? andpp multiplicities, respectively. The 110 GeV/cK ^?p data show significant correlations between the numbers of slow forward and slow backward particles, whereas the multiplicities of fast forward and fast backward particles are independent.     

Fragmentation of56Fe in Al at 1.88 A GeV

Summary The production of fragmented nuclei from relativistic⁵⁶Fe beam available from LBL Bevalac at 1.88A GeV has been studied using CR-39 (DOP) passive detector placed at an angle of 60° with respect to the beam. The histogram showing the experimental frequency distribution of minor axes of the elliptic etch pit shows the presence of the fragmented nuclei produced with charge numberZ from 25 up to 21. The histogram further reveals the presence of nuclei withZ=27 and 28. The production of nuclei heavier than⁵⁶Fe is possibly due to the charge exchange or pick-up phenomena.

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Riassunto Si è studiata la produzione di nuclei frantumati da un fascio di⁵⁶Fe disponibili dal Bevalac LBL a 1.88A GeV usando un rilevatore passivo (DOP) CR-39 a un angolo di 60° rispetto al fascio. L'istogramma che mostra la distribuzione di frequenza sperimentale degli assi minori dell'etch pit ellittico rivela la presenza di nuclei frantumati prodotti con numero di caricaZ da 25 a 21. L'istogramma rivela inoltre la presenza di nuclei conZ=27 e 28. La produzione di nuclei più pesanti del⁵⁶Fe è probabilmente causata dai fenomeni di scambio della carica o fenomeni di pick-up.

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Резюме Исследуется рождение фрагментированных ядер от релятивистского пучка⁵⁶Fe, имеющегося в LBLBevalac, с энергией 1.77A ГэВ. Для исследования используегся пассивный детектор CR-39 (DOP), расположенный под углом 60° по отношению к пучку. Гистограмма экспериментального частотного распределения обнаруживает наличие фрагментированных ядер, рожденных с зарядовым числомZ от 25 до 21. Гистограмма также обнаруживает наличие ядер сZ=27 и 28. Рождение ядер с зарядами, превышающими заряд железа, оказывается возможным, благодаря процессам перезарядки.

     

Charged multiplicities in K−p interactions at 100 GeV/c

The charged multiplicity distribution is presented for K^?p interactions produced in the hydrogen bubble chamber, BEBC, using an r.f. separated, tagged K^? beam of 110 GeV/c momentum. A comparison with K⁺p, πp and pp data at lower energies shows that the main features of the multiplicity distributions depend on energy and charge of the incident particles, but not on their strangeness. At high energies, only the energy is important.