Molecular plating of actinides on thin backings

Abstract

Actinide targets on thick and thin backings are needed for experiments at heavy-ion accelerators. One of the efficient ways to prepare such targets is by molecular plating. Although many laboratories have successfully prepared targets on thick backings by this technique, it is quite difficult to make targets on thin backings (100 μg/cm 2 up to 1 mg/cm 2). In recent years, we have plated targets on thin Ni and carbon backings, for example 234U targets on a 200 μg/cm 2 Ni backing. The Ni foils, evaporated on a copper substrate, are available commercially. We used these foils to plate 234U and afterwards we removed the copper by dissolving it in a mixture of ammoniacal trichloroacetic acid. In this way 400 μg/cm 2 234U targets were prepared on a 200 μg/cm 2 Ni backing. A 100 μg/cm 2 243Am target was prepared by plating onto a 75 μg/cm 2 carbon film left on its glass substrate for later floating. We found that a plating cell made from Teflon was difficult to use because it scratched the C film producing a liquid leak at the joint of the column and the C film. This sealing surface needs to be extremely smooth to avoid leakage. A column made of Delrin™ was then tried and did not produce any scratch on the carbon film surface. This column was used to prepare 100 μg/cm 2 243Am targets. Details of the technique will be presented.