AW: beta's in my coffee creamer

["Franz Schoenhofer" <franz.schoenhofer@CHELLO.AT>]

Dear Henk,



I might be able to help you (I have worked for more than 25 years with LSC),

but I need a few informations first in order not to start with mere

speculations!



What does your "coffee creamer" consist of? Did you suspend the powder in

the cocktail? Is it the form I have seen, which is actually a synthetic

product, using some calcium compounds as far as I remember and not

containing anything derived from milk? Or is it derived from milk and

substantially dry milk? If the latter is the case, then you have measured

the K-40 which is present in all milk and would be concentrated considerably

of course in dry milk. Obviously you use some Packard counter, because you

give "keV". (BTW: To call the units "keV" is an incredible wrong statement

by Packard, which they have not stopped since decades: The units are "pulse

heights", because the same radionuclide will be measured in different

"keV"-windows when the quench changes, but the electron energies will of

course remain the same.) So I guess that you have no access to a spectrum -

otherwise you could very easily verify this, one method being to use an

internal standard of K-40 and quantifying the amount. One should not forget

the possible contribution of C-14.



Secondly:

I suppose that "demi-water" means demineralized water. Obviously you have

pulses in the lowest energy region, which vanish after a day. This is a

clear hint that you observed luminescence - I bet a bottle of Bokma Oude

Jenever on it. Again if you had a spectrum you would be able to see a sharp

peak which would be at even lower energies than tritium. You could compare

this peak with the peak from chemoluminescence produced by adding a few

drops of hydrogen peroxide to the vial with your sample. For

Cherenkov-effect you would have to have a high-energetic beta emitter and

the spectrum would be significantly different from both chemiluminescence

and tritium.





I have some experience both with milk and unexpected luminescence:



In the aftermath of the Chernobyl accident I tried to shift a part of the

Cs-137-measurements of milk from our germanium-detectors to LSC and looked

at the possibility to measure it with LSC. K-40 was really disturbing the

measurements, but we could subtract its approximate contribution from the

total spectrum as long as there was enough Cs-137 present. During a visit to

Kiev in 1987 I tried an approach for a fast method for the measurement of

Sr-90 in milk by LSC, by simply mixing the milk with cocktail and analysing

the spectrum, but I had just a few hours time for that task and it seemed

that there were other interferences.



I have also done a lot of C-14 measurements in wine and spirits to determine

the age of these liquids. For spirits I used the approach to measure the

C-14 directly after mixing with the cocktail. In one case (spirit made from

rowanberry - Eberesche, Vogelbeere) I observed a really persisting

chemiluminescence which lasted for more than a week, declining during that

period.



Best regards,



Franz













-----Ursprüngliche Nachricht-----

Von: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu]Im Auftrag von H. Westenbrink

Gesendet: Freitag, 09. Juli 2004 11:03

An: radsafe@list.vanderbilt.edu

Betreff: beta's in my coffee creamer







To my surprise I found beta's in coffee creamer, when I

counted a mixture of creamer and scintillation fluid (ultima gold)

in a LSC at 0 - 156 keV. There was a significant difference with

the blanc.

When I mix creamer with demi-water I see in the LSC at 0-19 keV

a significant difference with the blanc (cherenkov?). Only at day one



Can anybody tell which isotope I see?



Henk Westenbrink

h.westenbrink@amc.nl

Central B-laboratory

AMC  Amsterdam



************************************************************************

You are currently subscribed to the Radsafe mailing list. To

unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu  Put the

text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,

with no subject line. You can view the Radsafe archives at

http://www.vanderbilt.edu/radsafe/



************************************************************************

You are currently subscribed to the Radsafe mailing list. To

unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu  Put the

text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,

with no subject line. You can view the Radsafe archives at

http://www.vanderbilt.edu/radsafe/