Hi List, Peter,
Could you give a little more detail, as 22Na has a half life of about
950 days and the experimental uncertainty of that particular measurement
apparently used to calculate the ratio was 11.6%, not to mention worse
uncertainties with the 26Al. It says the measurement was between
December and January of 2006.
So for starters, did they measure the meteorite 9 months before it
fell?
OK, so maybe it is a typo in the link you gave (source or on line
Meteoritical Bulletin, but the same January 2006 date is currently on
Svend´s website) and say they are both typos which may or may not say
something about precision: and should read January 2007.
If we assume the measurements were taken about 75 days after the fall
and we throw around a ten percent order of magnitude as the possible
measurement error, would not the difference of 4 days (October 12 vs.
Oct. 16) be totally lost in the error?
It is more likely the measurements were just to prove it was a fresh
fall, but the ability to distinguish four days based on a bunch of
assumptions of the original composition seems far-fetched to me. That
must be what the scientists set out to prove.
So, maybe the gamma spectroscopist had received the October 12 date and
only set out to prove it was reasonable. Surely if they had received
the October 16 date, they would have allowed it as consistent as well -
after all, over
99.7% of the 22Na would still be there (did I do that
right?), and this is dwarfed by the experimental error.
As Jim mentioned I think a real witness needs to speak up ... the
press, as reported by Svend Buhl, has October 16 as the fall date. So
at the moment, it would seem the press is preferable to insignificant
digits being extended...
Best wishes,
Doug
-----Original Message-----
From: Peter Marmet <[email protected]>
To: [email protected]
Sent: Sun, Oct 11, 2009 3:28 pm
Subject: Re: [meteorite-list] Bassikounou OCTOBER 16th
Hello Thomas,
Cosmogenic radionuclides:
(P. Weber, PPGUN) Gamma-spectroscopy performed in December-January
2006 showed the presence of the following radionuclides: 48V, 46Sc,
56Co, 54Mn, 58Co, 7Be, 51Cr, 57Co, 22Na, 26Al and 60Co.
Recalculated to 12 October 2006 22Na was 38.0±2.2 and 26Al 31.5±2.1
(both dpm/kg), the activity ratio of 1.21 is fully consistent with a
fall on that date.
More info here: http://kuerzer.de/1u0Y557jF
Cheers,
Peter
2009/10/11 Thomas Webb <[email protected]>:
Jim and List,
The bulletin shows a discrepancy concerning the fall date. In the
data table
it gives October 12, 2006 but in the writeup it is October 16. I
belive I was
the first to offer any on ebay and at that time I gave the fall date as
Oct. 12
and still have that date in my
database. However, perhaps a corrected
date was
offered later.
Can someone give us confirmation of the actual date that it fell?
Thanks,
Thomas
--- On Sun, 10/11/09, Jim Strope <[email protected]> wrote:
From: Jim Strope <[email protected]>
Subject: [meteorite-list] Bassikounou OCTOBER 16th
To: "Meteorite Central" <[email protected]>
Date: Sunday, October 11, 2009, 10:29 AM
http://tin.er.usgs.gov/meteor/metbull.php?code=44876
Jim Strope
421 Fourth Street
Glen Dale, WV 26038
http://www.catchafallingstar.com/
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