normal background for cs137, etc.
Do you have "normal" (pre-Japan) background values for cs137, or any of the other isotopes being measured? I assume there's still some cs137 lingering from atomic tests, Chernobyl, etc.? By the way thanks for putting your results on the web!
I'm not aware of Cs-137
I'm not aware of Cs-137 having been observed in natural backgrounds in California, nor any of the other isotopes. However, I know that in Europe Cs-137 is an easily observed part of the natural background. I do not know what concentration they have.
The other isotopes are too short-lived to be around in any significant concentration from Chernobyl.
As for weapons tests, these isotopes could be measured by sensitive instruments (and, in fact, sensitive monitoring of certain fission products is used to detect weapons tests for purposes of arms treaty verification), but are quickly diluted in the atmosphere, ocean, etc. so there is generally no observable level of these isotopes in the natural background.
Also, the observation of isotopes from weapons tests would depend strongly on where the test was performed and the weather patterns surrounding it.
Cs-137 is not in our background
Cs-137 and the other isotopes are never in our background. To see the background in our lab, we just posted a spectrum of deionized water taken with the same equipment here. If you look in the region around 662 keV, you won't see the Cs-137 line. All lines labeled in the plot are known backgrounds.