Those eBay R1538 PMT deals (two for $9.97) combined with plastic scintillator material from OE Technoloiges (www.oetech.com)
along with a Pepperidge Farm cookie tin and one BNC and you have a nice Ludlum/Eberline compatible scintillator probe.

Below is a photo of the insides.  R1538 PMT rewired as per my instructions.
The R1538 is a great deal because it has a pre-wired dynode resistor string...no funky socket required!
The plastic scintillator material is attached via tape to the front of the PMT.
(For enhanced optical performance wrap the scintillator in white paper
on the back and sides but not the PMT side.)
 

Below is a photo of the completed setup (cost < $25).
(That's a little 111b radioactive check disk below the box)
The easy-open box is good for quick-testing various scintillator materials.
For use in sunlight wrap one strip of black electrical tape around the lid to seal out light.
This detector is easily capable of measuring the backgound radiation of the soil.

The cookies were good...yum!
 
 

4/11/2002