The Mineral Spectroscopy Lab. (Prof. G.R. Rossman)

Cs-137 gamma irradiator

 
sample area

The sample area is about 1.5 inches diameter and 2.8 inches tall.  

 

This cell can irradiate a sample at the rate of about 600,000 rad per day. 
In a typical granitic geological setting, the host rocks may generate a similar dose in about 2 million years.