For those looking for a complete flesh-out of how to make an amateur neutron detection scheme using these Russian tubes found on E-bay, Bob Higgins has done all the leg work and heavy lifting in his recent and superb 43 page paper on the subject. You will learn a lot related to neutron detection in general and about the details on how to make your own counter around this special form of 3He tube.
I have attached, below, the PDF of this paper. This is what I consider the ultimate DIY and informative paper on this Russian tube.
Bob is already updating and posting the modified PDF of this paper. The latest version can be found at...
https://drive.google.com/open?id=0B5Pc2 ... VpNc2NhOWM
It is folks like Bob Higgins that supply open source info of this sort that allow the citizen scientist to also join in research with serious and useful data and instrumentation.