Hi James,
the last ten or so SAES getters we have used (mostly NP-10 type) do
not add to our helium blank in any measurable way (hot or cold). In
quantitative terms our blank on mass 4 is less than 5e8 atoms (over
say 30 mins, and assuming sensitivity is linear over a wide range of
pressure), and the getters never contribute above this level.
What about just isolating the getters to take them out of the
equation? Can you make measurements with the getters valved off?
all the best,
Jim Dunlap
>Does anybody have a feeling for how long it takes for 4He degassing from
>SAES getters (type NP10) to stop being a problem (e.g. a half-life or number
>of activation cycles?). We are purchasing a new instrument with a very low
>specified 4He blank (~10E5 atoms), and the vendor is blaming the blank
>entirely on the getters...
>
>James Whitby
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