EVAPORAÇÃO DE Sb E 123 Te SOBRE Au PARA CONFECÇÃO DE ALVOS UTILIZADOS EM MEDIDAS DE VIDAS-MÉDIAS DE ESTADOS NUCLEARES EXCITADOS

Enriched 128Te and Sb targets of about 1mg/cm2 were prepared on Au backings by the electronic bombardment echnique. These foils were use in nuclear physics experiments with heavy ions, 121,123Sb(16O,4n)133,135 Pr e 182Te(4N,5n)137Pr, in order to measure lifetimes of excited nuclear states [1] in the range of 1 to 10010-12s. These measurementes requier a special apparatus - called "plunger" - where a thin extremely flat target is arranged rigourously parallel to the stopper and their relative distance is modified in steps of the order of microns. The basic characteristics of the targets and stoppers used in experiments with "plunger" will be discussed.