| Description |
A method is described that utilizes the energy of ultraviolet Cerenkov radiation, concentrating this light into a small area. The ultraviolet photons are wavelength shifted by the waveshifter Popop, which is contained in a coating on the surface of methyl methacrylate plastic sheets. This transparent coating is made by dissolving 1.25 grams of Popop per liter of a base solution of 15 grams of plastic and a liter of the solvent ethylene dichloride. The resulting coating is approximately 10^-4 in thick and gives an area concentration of Popop of 26ug/cm^2 of surface. When applied by a dipping process this coating leaves the surface smooth and optically clear. This allows the sheets to be used as light pipes to conduct the light to phototubes coupled to the edges of the sheets. it was found that such a sheet placed in a distilled water Cerenkov counter acted as an efficient light collector. The coating shifted the ultraviolet radiation as effectively as the water soluble shifter Dupong MDD 3169 added directly to the water and, in addition, reduced the required number of phototubes while preserving information about the direction of the radiating particle. The method is thus very useful for large Cerenkov Counters. |
