AW: AW: Radioisotope Efficiencies

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

-----Ursprüngliche Nachricht-----

Von: Joel T. Baumbaugh [mailto:baumbaug@spawar.navy.mil]

Gesendet: Freitag, 20. Februar 2004 21:12

An: Franz Schoenhofer

Cc: Joel Baumbaugh; William V Lipton; radsafe@list.Vanderbilt.Edu

Betreff: Re: AW: Radioisotope Efficiencies





Franz,



Your sarcastic comment about my LSC radioisotope efficiency results

rolls off of my back like water on a duck.  Thank your for your offer

of .help. (no doubt to see the error of my ways), but I imagine that I

and the others (including Beckman/Packard) will stand by our figures

(with provided disclaimers).  BTW, do you own "stock" in Quantulus?



V/R,

--------------------------------------

Joel,



Your response to my comment on your LSC-message is one of the biggest

surprises on RADSAFE though I participate in this newsgroup since many

years. My comment was not in any way sarcastic (how can you write anything

like that?), so there is nothing to "roll off of your back". The part of my

comment you cite in your answer was merely scientific, but giving the fact

that I answered it at about 2:00 am I did not want to go into details. We

could have figured them out through private channels. Since you went to the

list, please find my reasonings below.



My offer for help was intended to send you papers in which I describe

optimisation and influence of different factors on efficiency, background,

figures of merit and LLD's - if you were interested of course, leaving it

open to you, whether you want this kind of help or not. You cannot expect a

list of efficiencies of "unquenched samples", , because I declared that in

my field of work the efficiency is of very low importance. I explicitely

stated that you had correctly given the conditions for your measurement

results (unquenched samples), so that one comment received on that was not

really valid. Did you accuse the other posters as being sarcastic as well,

because they pointed out the importance of vial, cocktail etc. or are you

attacking only me of unknown reasons?



I was of the obviously wrong opinion that you "volunteered me" to answer

your contribution by mentioning my name in the original post. So please, if

you do not want to receive any reaction from me, refrain from mentioning my

name in the context of your contributions, though I cannot guarantee that I

would not answer.



Your comment on, whether I own stock in "Quantulus" is not really sincere -

or is it? "Quantulus" is not a company, I bought these instruments because

there is no doubt within serious scientists, that this is the by far best

suited instrument for ultra low-level counting. The cost of these

instruments, which were of course heavily discounted, were earned within one

or two years of operation, especially in the Austrian Radon Project. The

instrument was manufactured by Wallac Oy (Turku, Finland) and this company

has changed ownership over the last decades several times. I do not even

know by heart, which company now owns it. For your information: Packard is

owned by the same company now. I need not apologize for using whatever kind

of instrument I use.



But to return to my "sarcastic comments":



You give for C-14 (156,5 kev, 100% decay by this way) an efficiency of 96%.

(This seems remarkable and unbelievable, but let us assume that it is

correct.) For Cr-51 (4.4 keV, 66.8%) you give 80% efficiency as well as for

Co-57 (80%) as compared to 60-65% for tritium (gratulations!) (18,62, 100%).

Let us go to the natural decay chains. I just wonder, how you measure them.

Everybody involved in these measurements knows about the problems to

distinguish the radionuclides involved. I can hardly believe that you had

pure Pb-210 for measurement, but if you had you would not have had 100%

efficiency for Pb-210, being a weak beta-emitter slightly higher in energy

than tritium. How did you measure Ra-226 - did you have freshly separated

Ra-226, measured within seconds of separation? I hope you know (sarcastic!)

that Rn-222 will grow in considerably within a very short time, not to talk

about radons shortlived progeny.



If you want some more arguments for my serious doubts - I can provide them.

They are absolutely independent of the kind of equipment used.



I do not believe that this kind of discussion is positive for LSC. Since you

put your accusations to the list, I reply to the list as well.



I am available for any further discussions, whether privately or within the

list.



Best regards,



Franz









I do not know, what V/R means, but you might enlighten me.







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