A new conducting polymer radioactive source support for 4 pi beta-gamma coincidence counting

Gold-coated Vyns or collodion membranes stretched on stainless steel rings are generally used for the preparation of high quality 4 pi beta-gamma coincidence counting sources. We propose an alternative method for the preparation of such high quality sources by the use of a low-Z composite conducting polymer; [poly(3,4-ethylene dioxythiophene)\poly(vinylchloride)]. A solution containing an EDT monomer (3,4-ethylene dioxythiophene), an oxidizing agent [Fe(CH3-phi-SO3)(3)], PVC, and tetrahydrofuran as solvent is spin-coated onto a glass substrate. After coating, the membrane is dried in a convection oven to polymerize and oxidize the EDT. The membrane (PEDT/PVC) is then removed and transferred to the surface of a water bath before being deposited on a stainless steel ring. The main advantage of this procedure is the one step chemical curing/doping which takes little time in contrast to other methods. PEDT/PVC has lower electrical conductivity than PEDT alone but the PVC provides the required tensile strength for the membrane self-support. Qualities of Co-60 sources prepared with PEDT/PVC membranes and usually used films are compared. Parameters like beta detection efficiency, homogeneity and aging are discussed. (C) 1997 Elsevier Science B.V.