Particle Multiplicity Fluctuations Research Articles

Localized charged-neutral fluctuations in158AGeV Pb+Pb collisions

Localized fluctuations in the multiplicity of charged particles and photons produced in central 158A GeV/c Pb+Pb collisions are studied. The charged versus neutral correlations in common {eta}-{phi} phase space regions of varying azimuthal size are analyzed by two different methods. The analysis provides a model-independent demonstration of nonstatistical fluctuations in both charged particle and photon multiplicities in limited azimuthal regions. However, no correlated charge-neutral fluctuations are observed, contrary to expectations for the production of a disoriented chiral condensate. The result is not explained by the widely used VENUS model.

Simulations of the performance of the MVD in PHENIX

The PHENIX Multiplicity Vertex Detector (MVD) provides event characterization, a centrality trigger, collision vertex position, and measures fluctuations in charged particle multiplicities. The design criteria include a large rapidity coverage, good azimuthal coverage and granularity, minimizing material in the electron arm acceptance, and minimizing costs. The MVD contains two concentric barrels of Si strip detectors with two disk-shaped Si pad detector endcaps. Simulations show that the vertex position can be located to within a few hundred microns using hits in the barrels. A channel multiplicity signal is formed for use in the Level-1 trigger. The effect of the expected discriminator performance on this trigger signal will be shown. The pad and strip detectors are read-out with identical electronics. The influence of the performance of the electronics on the detector's performance are discussed.

Intermittency and multifractality of medium-energy particles in proton-nucleus interactions at 800 GeV.

We investigate the intermittent and multifractal behaviors of the multiplicity fluctuations of medium energy particles in 800 GeV proton interactions with emulsion nuclei. For our analysis, we have used ordinary scaled factorial moments (SFM) denoted as ${\mathit{F}}_{\mathit{q}}$, modified SFM, (${\mathit{F}}_{\mathit{q}}^{\ensuremath{'}}$) and modified multifractal moments, (${\mathit{G}}_{\mathit{q}}^{\ensuremath{'}}$) with suppressed statistical contributions. For a close comparison between the ${\mathit{F}}_{\mathit{q}}^{\ensuremath{'}}$ and ${\mathit{G}}_{\mathit{q}}^{\ensuremath{'}}$ moments, they have both been expanded in a set of basic functions each of which has a characteristic fractal behavior as a function of the resolution in phase space. The experimental values of anomalous fractal dimensions ${\mathit{d}}_{\mathit{q}}$ and Renyi dimensions ${\mathit{D}}_{\mathit{q}}$ are determined for q=2-5. The latter are corrected for statistical contamination in the multiplicity fluctuations. The observed variation of ${\mathit{d}}_{\mathit{q}}$ and ${\mathit{D}}_{\mathit{q}}^{\mathrm{dyn}}$ with q supports a self-similar random cascading mechanism for the particle production process. It is found that ${\mathit{D}}_{\mathit{q}}^{\mathrm{dyn}}$+${\mathit{d}}_{\mathit{q}}$=1.

A FULL-ACCEPTANCE DETECTOR FOR SSC PHYSICS AT LOW AND INTERMEDIATE MASS SCALES: AN EXPRESSION OF INTEREST TO THE SSC

A FULL-ACCEPTANCE DETECTOR FOR SSC PHYSICS AT LOW AND INTERMEDIATE MASS SCALES: AN EXPRESSION OF INTEREST TO THE SSC

Intermittency in 32S+S and 32S+Au collisions at the CERN SPS

Nonstatistical or “intermittent” fluctuations of charged particle multiplicities have been investigated at the CERN SPS with the WA80 multiplicity array for 32S+S and 32S+Au collisions of varying centrality. Within the phase space domain studied there is no evidence for intermittency in these collisions beyond that accounted for by FRITIOF filtered through a full detector simulation.