[Mitch]

Berkeley has an institutional lisence I didn't pay anything to view it.

[KLB]

Berkeley has an institutional lisence I didn't pay anything to view it.

And us poor schleps on the outside get left in the dark. 

No wonder you are finding things that I couldn't find.

I'm afriad my money is better spent buying another book on the periodic table in general than answering a trivia question for one element.  Validating all data on my table is much more important than posting a little bit of trivia about one element.

What is really killing me is that I can't find multiple offline sources that contain cross section data.  I found one source about seven years ago, but never found a second book that contained this information and over the years some questions have been raised about the accuracy of my data.  I finally pulled this data point from my element pages until I can find new sources to validate my information.

I swear that some times I can have three different "reliable" printed sources all showing a different figure for a single data point.     I figure twenty years from now someone will still find a data error on my periodic table or claim that their source shows a different figure and I'll have to break out all 6E6 books and charts I'll have on the subject and have to do some kind of statistical analysis to figure out what the best answer is.

[Borek]

I swear that some times I can have three different "reliable" printed sources all showing a different figure for a single data point.

Nothing unusual, happens all the time. I observe the same in books with equilibrium constants (dissociation, complex creation, solubility products, redox potentials).

[KLB]

I swear that some times I can have three different "reliable" printed sources all showing a different figure for a single data point.

Nothing unusual, happens all the time. I observe the same in books with equilibrium constants (dissociation, complex creation, solubility products, redox potentials).

I"ve gotten so many "your data is all wrong" comments because of this that I'm actually having someone write me an article I can publish about why this happens.

The worst data points are the year of discovery and who discovered each element. There is so much intrigue into who gets credit for discovering elements that I have started adding additional notes on just this issue for each element.

[zaphraud]

Here ya go: Pu-239 once existed in nature, briefly (its decay products were found):
http://www.physicscentral.com/explore/action/reactors-research.cfm

It seems blue-green algae were enriching uranium enough to build reactors long before humans even existed. Pity that hippies are so terrified of carbon-neutral power that the world is now on the brink due to all the coal use.

But then again, coal is dirty, hippies are dirty - must just be a professional courtesy to ignore its harm.

[gippgig]

Trace amounts of Pu-239 occur in uranium ores as a result of capture of stray neutrons by U-238; typically there is about 1 atom of Pu per trillion of U. One early reference is JACS 70 1571.
It has been reported that trace amounts of Pu-238 also occur in uranium as a result of double beta decay of U-238 - I believe the reference is Physical Review Letters Dec. 2, 1991 (haven't confirmed).