[time-nuts] CS reservoir depletion

Robert Vassar rvassar at rob-vassar.com
Sat Jan 15 03:57:40 UTC 2011

On Jan 13, 2011, at 5:18 PM, Rick Karlquist wrote:

> The other problem for the garage builder is that one of the Rb
> isotopes is slightly radioactive.  Probably not OK to have
> in your garage.

I used to perform Rb/Sr geochronology "wet bench" chemistry in  
college.  Rb-87 has a half-life on the order of ~48.8 billion years.   
Several multiples of the estimated age of the universe.  The  
potassium-40 in your own body is a much greater threat, followed by  
C-14, and various natural sources, smoke detectors, camping lantern  
mantles, etc... I understand the average person has several thousand  
K40 decay events in their body per second.

Handling pure Rb is another thing entirely.  It is quite moisture  
sensitive / pyrophoric, and tends to form shock sensitive peroxides  
even when submerged under oil.  You really need to store the stuff in  
a vacuum, or under an inert atmosphere.  But since we're also  
discussing Cesium, I should point out that it is actually far worse  
in this regard.  You could probably safely handle a small quantity of  
Rb in a home lab environment for a short period of time.  Pure Cesium  
would be a significant risk.


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