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Author Topic:   Several specific questions about RadioCarbon Dating using AMS
RAZD
Member (Idle past 341 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


(1)
Message 4 of 30 (777257)
01-28-2016 9:02 AM
Reply to: Message 1 by PhiloNibbler
01-28-2016 2:23 AM


calibration of equipment
Hello PhiloNibbler, and welcome to the fray

Again, I'm just trying to find out more information to better understand the process. Thanks

From what I see and know, this is about calibrating the machines to determine their potential error envelope

... The lowest 14C/13C ratio we have measured is for geological graphite, which yields lo-15 PA of beam current at less than 0.05% of the i4C/i3C ratio for the modern reference standard. ...

So the potential error in measurement of an actual sample would be +/-0.05% of the i4C/i3C ratio for the modern reference standard. Seeing as this measurement of age is based on exponential decay this does not result in a major error in ages <50,000 yr BP, which is considered the current limit of 14C/13C testing.

Again, I'm just trying to find out more information to better understand the process. Thanks

There are a couple of members that are involved with 14C testing\measurements. PurpleYouko comes to mind, as does Coyote, and they may be able to help.

Enjoy


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This message is a reply to:
 Message 1 by PhiloNibbler, posted 01-28-2016 2:23 AM PhiloNibbler has not yet responded

  
RAZD
Member (Idle past 341 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


(1)
Message 25 of 30 (777418)
01-30-2016 5:23 PM
Reply to: Message 23 by Minnemooseus
01-30-2016 4:54 PM


Re: Shells incorporating old carbon from non-atmospheric source?
I was under the impression that dating shells is a shaky proposition.

Indeed. You have the problem of the reservoir effect, and this is difficult to quantify for past data. There is a compilation of known present day reservoir effects due to the delay in moving CO2 from the atmosphere into the water and where sea water wells up from deep ocean currents

http://www.c14dating.com/corr.html

and an interactive map

http://radiocarbon.pa.qub.ac.uk/marine/

but this doesn't help you with fresh water reservoirs or where the carbon is accumulated from old dissolved calcite, limestone and the like.

one can assume that they are the same now as in the past, but that is an assumption that should be tested by other correlations.

Enjoy

Edited by RAZD, : .


we are limited in our ability to understand
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 Message 23 by Minnemooseus, posted 01-30-2016 4:54 PM Minnemooseus has acknowledged this reply

  
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