arXiv subjects
Publications and source records attributed to W. E. Cleland.
Directed flow of antiprotons is studied in Au+Au collisions at a beam momentum of 11.5A GeV/c. It is shown that antiproton directed flow is anti-correlated to proton flow. The measured transverse momentum dependence of the antiproton flow is compared with predictions of the RQMD event generator.
Directed flow of deuterons, tritons, $^3$He, and $^4$He is studied in Au+Au collisions at a beam momentum of about 10.8 $A$ GeV/c. Flow of all particles is analyzed as a function of transverse momentum for different centralities of the collision. The directed flow signal, $v_1(p_t)$, is found to increase with particle mass. This mass dependence is strongest in the projectile rapidity region.
Two-particle correlation functions for positive and negative pions have been measured in Au+Au collisions at 10.8~GeV/c per nucleon. The data were analyzed using one- and three-dimensional correlation functions. From the results of the three-dimensional fit the phase space density of pions was calculated. It is consistent with local thermal equilibrium.
Utilizing the Lorentz invariance of the correlation function we study the effects of anisotropic transverse flow on the HBT correlation function. In particular we show that directed flow would evidence itself by non zero ``side--long'' and ``side--out'' terms in the correlation function. We also show that the study of ratios of the correlation functions evaluated on different event subsamples and/or different Lorentz systems provides information on the source dimensions and velocity which could be less biased by corrections of different kinds. We present a fitting technique appropriate for HBT analysis which does not require binning and is especially useful for multidimensional fitting.
The effects of anisotropic transverse collective flow on the HBT correlation function is studied. There exist three different physics contributions related to flow which affect the correlation function: anisotropic source shape, anisotropic space-momentum correlations in pion emission, and the effects related to the HBT measurement of the size of a moving source in different reference frames. Resolution of these contributions experimentally can lead to a detailed understanding of both collective flow in nucleus-nucleus collisions and the HBT technique itself. A method is presented which permits the derivation of model independent relations between the radius of a source measured in a frame in which it is moving and in its rest frame.