🚀 go-pugleaf

I am looking for some information about a surplus device I came across.
It is some sort of radiation detector.  It is a metal tube 3 cm in diameter
and 10 cm long.  On one end is a phenolic? base with four pins in a rough
square pattern (two large pins and two smaller pins).
The other end is covered by a soft yellow plastic cap which removes easily
to reveal a transparent window beneath.  Inside the tube (beneath the window)
is a pin fixed to the center of the back of the tube.  The pin is about  
5 cm long and terminates just short of the window.  At the end of the pin is
a shiny grey bead about 3 mm diameter.  The pin is about 1 mm dia.
It is manufactured by Searle Analytic Inc. and is model # 000-000108 047 A
The plastic cap has a metal washer in it that covers all but about 1 cm in
the middle.
Any ideas for a use for this gadget?
A trash can is probably the best home for it, but I thought I would ask.
Thanks.
--keith