No abstract

Identified pi(+/-), K(+/-), p, and (-)p transverse momentum spectra at midrapidity in sqrt[s(NN)] = 130 GeV Au+Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average transverse momenta increase with the number of participating nucleons in a similar way for all particle species. Within errors, all midrapidity particle yields per participant are found to be increasing with the number of participating nucleons. There is an indication that K(+/-), p, and (-)p yields per participant increase faster than the pi(+/-) yields. In central collisions at high transverse momenta (p(T) > or =2 GeV/c), (-)p and p yields are comparable to the pi(+/-) yields.

Liquid-crystal cells shaped like a plano-convex lens or a plano-concave lens are prepared. The focal length can be varied from the value fe for an extraordinary ray, where the liquid-crystal cell takes a homogeneous alignment, to fo for an ordinary ray, where it takes a homeo-tropic alignment, by applying an electric field or a magnetic field across the lens-cell. The focal length in the lens-cell with the homogeneous alignment can also be switched between fe and fo. This is done by switching the direction of polarization of the incident light by applying a voltage across a TN cell sandwiched between the polarizer and the lens-cell. Since the thickness of the liquid-crystal layers increases in the lens-cells, the optical transmission properties are investigated as a function of the cell thickness.