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Re: orion-list Radiocarbon

On Sat, 28 Aug 1999 13:49:58 +0200, gd@teol.ku.dk writes:
>
>
>Tom Simms: 
>
>>    Again, you address nothing of the handling treatment by the
>>    recovery teams and the analysis people.  I've heard of some
>>    cavalier treatment.
>> 
>That's already been fully acknowledged; you're being repetitive, friend.  
>Lab pretreatments are effective in getting out most routine contaminants
>(including cigarette smoke); that is probably not the problem.  

   Up to five years ago, I wasn't.  Things have improved since, not
   perfect but much, much better.  Still, the hands on excavators 
   need reminding that not ALL that they do can be remediated.

>The 
>issue of the handling and uncertainties concerning chemicals or oils 
>applied to the scrolls is a problem.  

>The Zurich lab's independent dating 
>of subsamples treated partially and then fully, and checking for 
>discrepancies in the measurements, diagnosed contamination on 
>4QTQahat (prior to chemical pretreatment).  What some may not 
>appreciate--listen up Tom!--is that in their 13 other items Zurich found 
>no significant discrepancies through this procedure, indicating presumably 
>no contamination.  Its true this is not infallible, and an odd case of
>a contaminated sample could still slip through undetected by chance,
>but still, this is important information.  This Zurich information indicates
>that, statistically, most of the scrolls samples are probably not 
>seriously contaminated, and therefore can be expected to give 
>accurate radiocarbon dates after standard lab pretreatment.  This is 
>absolutely not a situation of contamination ruining all scrolls dates, 
>showing the radiocarbon method is unusable, etc.  Please Tom, 
>before posting again on contamination read the section in my 
>article in Flint and Vanderkam where this is discussed in detail (or 
>else look up the original Zurich report in Atiqot 1991 on this), and 
>contact me offlist if there is anything unclear or difficult to understand.

   The above is good to know but I repeat what I said above that 
   excavators must be more careful than they have been in the past.

>The problem of sample contamination from unknown sources affecting 
>certain Scrolls dates is a technical problem that is solvable, and I 
>believe is going to be solved.  Every battery is going to learn some 
>things from previous mistakes, and perhaps make new ones, to be 
>critiqued and improved by the next battery.  That is the way it works.  

   Again, I'll say as I did before, now that you've posted the ranges,
   Particulalry the Bar Kochba data, that I'm satisfied with my view on
   1ST C BCE for deposoti and for contra a 1ST C CE one.  

>This is the correct procedure--do a battery, digest the results, frame 
>new questions, do a battery, digest the results, frame new questions, 
>do the next battery, etc.  I dearly hope this process continues on the
>Dead Sea texts so long as there are unanswered, but answerable, 
>questions remaining.

   Right.  AND, I suggest the Labs need to shift gears to using
   other systems and making those, their parameters and those of
   Carbon dating more widely known.

>Greg Doudna
>Copenhagen
>

  Ciao -

Tom Simms




For private reply, e-mail to Tom Simms <tsimms@mailserv.nbnet.nb.ca>
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