109

Cd is a radioisotope with a half-life of 453 days and its decay daughter

109m

Agemits 22 keV X ray and 88 keV

γ

ray. Since the absorption coefficients of the 22 keV X ray in water and oil are significantly different

the

109

Cd is very suitable X ray source as oil-water analyser for the determination of fraction of water contained in oil(water/oil ratio). Considering the rather low energy of 22 keV X ray

we used the molecular plating method which has the advantages of high deposition efficiency

and short deposition time. The plating layer are thin

uniform

less self absorption and strongly adhesive to the base material. The intensity of

109

Cd X ray source prepared is 1×10

7

/s.