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Tue, 28 Jun 2005 10:29:36 -0400 |
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Tim,
We have had a very similar issue with our 253 after we cleaned the
source; low sensitivity and slow signal rise. We couldn't solve it by
changing filaments and a turbo pump. What Roger (Finnigan engineer)
found was that our filament was a bit miss-aligned by "about half a
mm". The way to check is to take off the electron trap and look at the
filament from the other side of the source. I presume Delta source has
the same basic structure with that of 253. You need to align the
filament in the middle, otherwise you won't get a good flow of
electrons hitting your molecules; half a mm is very critical here. I
am not sure if your issue is the same but I thought it might worth
checking before doing something laborious. I thought annealing was to
do with baking the organic molecules off the ceramics but I am not
sure. You don't bake the metal part because it gets oxidized.
Hope this helps.
Shuhei
--
Shuhei Ono
Geophysical Laboratory
Carnegie Institution of Washington
5251 Broad Branch Rd., NW
Washington, DC 20015
tell) 202-478-8988
Fax) 202-478-8901
On Jun 27, 2005, at 12:17 PM, tcp121 wrote:
> Greetings...
>
> When cleaning the ceramics of the ion source for our Delta Plus XL I
> used a bead blaster to get rid of the ion burn rather than a diamond
> file. The end result is the same. But the next step in the procedure
> (found in the manual) is to anneal the ceramics. Does anyone know the
> reason for annealing? I wonder if it closes off pore spaces in the
> ceramics that are exposed when abrasively cleaned. The reason I think
> this is that I did not follow this step, and now my CO peaks on the
> Delta are now slow to rise and slow to fall, as if some CO is getting
> trapped in the system somewhere.
>
> Any thoughts? Is annealing necessary?
>
> Thanks...
>
> Tim Prokopiuk
>
> -----------------------------------------------
> Tim Prokopiuk
> B. Sc. Geology/Technician
> Saskatchewan Isotope Laboratory
> Room 241
> Department of Geological Sciences
> University of Saskatchewan
> 114 Science Place
> Saskatoon, Saskatchewan, Canada
> S7N 5E2
> Phone: (306) 966-5712
> Fax: (306) 966-8593
> Email: [log in to unmask]
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