[Sneap] Caesium Sputter Source and possible contamination from Ti hydride

[Thomas A Brown]

Chris,

   We have ongoing 3H AMS projects and run Ti-hydride targets in our 
sources for those projects.  We have found that running Ti-hydride in 
the ion source does (is likely to) have an undesirable impact on 
subsequent efforts to run 14C targets in the source.  We routinely 
consider just cleaning the source after Ti-hydride runs before 
beginning further 14C runs.  Our suspicions (which have included many 
theories - some conflicting but coming from the same person) tend to 
center on possible problems caused by the deposition of Ti (sputtered 
neutral ions?) all over the surface of the ionizer - but hard 
evidence is lacking.

Hope this helps.
Tom.


>Hi Guys
>Our SNICS Caesium sputter ion source is mainly used for C-14 Measurements.
>
>However, occasionally we use Ti-hydride targets for Proton beams.
>  When we then go immediately back to measuring C-14 targets ( without
>opening the source for cleaning etc) and we appear to have stability
>problems etc.
>Are there issues with possible contamination of the Caesium or other
>reasons that people have experienced?
>i.e. is there evidence against using Ti-hydride on a sputter source used
>for C-14 AMS mainly ?
>
>Thanks
>Chris
>
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Dr. Tom Brown
Center for Accelerator Mass Spectrometry
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