low dose rate survey inst.

[slaback@micf.nist.gov]

Several responders have suggested Victoreen 450Ps
(which I have and like).
Also to be considered is the Bicron MicroRem which
uses a plastic scintillator and is about a factor
of two more sensitive.
Another possibility is the NRC ADM-200.  It uses
a GM detector so there might be an energy response
problem at low energy, but it goes down to the 
microrem range.
Eberline also makes a new instrument to which you 
can attach multiple probes, one of which would
probably do the job.

Naturally all of the above is my personal opinion,
neither endorsed, condoned, or otherwise acknowledged
by my illustrious employer.

A little risk adds spice to life.
Lester.Slaback@NIST.gov