A NEW CONDUCTING POLYMER RADIOACTIVE SOURCE SUPPORT FOR 4-PI-BETA-GAMMA COINCIDENCE COUNTING

Gold-coated Vyns or collodion membranes stretched on stainless steel r ings are generally used for the preparation of high quality 4 pi beta- gamma coincidence counting sources. We propose an alternative method f or 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 di oxythiophene), an oxidizing agent [Fe(CH3-phi-SO3)(3)], PVC, and tetra hydrofuran as solvent is spin-coated onto a glass substrate. After coa ting, the membrane is dried in a convection oven to polymerize and oxi dize the EDT. The membrane (PEDT/PVC) is then removed and transferred to the surface of a water bath before being deposited on a stainless s teel ring. The main advantage of this procedure is the one step chemic al curing/doping which takes little time in contrast to other methods. PEDT/PVC has lower electrical conductivity than PEDT alone but the PV C provides the required tensile strength for the membrane self-support . Qualities of Co-60 sources prepared with PEDT/PVC membranes and usua lly used films are compared. Parameters like beta detection efficiency , homogeneity and aging are discussed. (C) 1997 Elsevier Science B.V.