Dear Hal and Nural,

Ca isotopes are routinely measured at our lab in Kiel. We measure 40-Ca
excess with a precision on the order of 0.05 permil (of 40-Ca/44-Ca
ratios). I never did 48-Ca/44-Ca ratios, but it should be possible with a
similar precision. This applies only for measurements of 48-Ca excess, i.e.
48-Ca enrichments/depletions NOT by mass-dependent fractionation (which
would simultaneously affect all other Ca isotopes according to their
masses). We cannot routinely do mass-dependent 48Ca variations at Kiel,
because we use a 48-Ca/43-Ca double spike to correct for machine fractionation.
There are several labs in the USA that do Ca isotopes (e.g. Berkeley,
Scripps, Caltech), but as far as I know they all use double spikes with 48-Ca.

Florian



At 04:16 04.11.04, you wrote:
>Dear listmembers,
>
>Can any of you help Nural out with his question concerning measurement of
>Ca isotopes?
>
>Thanks,
>
>Hal
>
>P. S. Please resond directly to Nurel ([log in to unmask])
>
>
>Hal,
>
>I am looking for ways of identifying abundance of Ca48 (see discussions
>below).  Sandy seems to think that you might have the equipment to do it.
>Thoughts?
>
>N
>
>
>
>----------------------------------------------------------------------------
>--------
>
>Nural Akchurin
>
>Department of Physics       Phone 806-742-3427
>
>Texas Tech University        Fax     806-742-1182
>
>Lubbock, TX 79409            http://highenergy.phys.ttu.edu
>
>----------------------------------------------------------------------------
>--------
>
>   _____
>
>
>
>
>
>A question? Hi Dom, I thought you or one of your colleagues might be able to
>help me with a problem I have at hand.   I need to determine the abundance
>of Ca48 in a sample with a reasonable accuracy.  The natural abundance is
>~0.18%.   So, either the absolute precision needs to be better than this by
>some amount or that the measurement can compare Ca48 to Ca40 in a relative
>measurement.  I have a few samples that are presumably  enriched.   But I
>would like to know how much (if at all)?  What do you think? Thanks. N
>----------------------------------------------------------------------------
>-------- Nural Akchurin Department of Physics       Phone 806-742-3427 Texas
>Tech University        Fax     806-742-1182 Lubbock, TX 79409
><http://highenergy.phys.ttu.edu> http://highenergy.phys.ttu.edu
>----------------------------------------------------------------------------
>--------


***************************************************
Florian Boehm
Leibniz-Institut f. Meereswissenschaften, IfM-GEOMAR
FB 2, Marine Biogeochemie/Ostufer
Wischhofstr. 1-3, D-24148 Kiel
Germany
email: [log in to unmask]
http://www.geomar.de/~fboehm/
Tel.: (49)431-600-2104
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