Neutron Detector Setup

[Ryan Catalano]

Upon request for the details on my detector setup, I created some quick videos of it in operation. My neutron detector consists of a SNMO-5 BF3 proportional tube connected to a Ludlum Model-12 ratemeter. I have experimented with different discrimination levels and voltages and I think I have achieved the best configuration I can get. In this video I'm operating the tube at around 1900V. The source I'm using is a 5 millicurie PoBe neutron source.

https://www.youtube.com/watch?v=nAOyQ9rT9-Y

[Richard Hull]

It seems to be counting neutrons and probably is, however, the the count should have increased dramatically. I assume the plate you put in before the source might have been a Be plate and your source a 5 mCi Po static eliminator. That plate needs to be in intimate contact with the source itself. You lose a lot of alphas between the source and the plate and what alphas do hit the Be are all degraded to lower energies (millions of air ionizing impacts). In many cases the lowered energies will not be capable of producing neutrons. A well constructed, good Po/Be source would have that rig going nuts! 300+ cpm! Your source is your issue and will remain so without intimate, zero range contact with the plate.

Remember, that your source is a static eliminator. They do not need the full alpha energies outside the casing. A weak and degraded 1mev alpha outside the casing will still ionize millions and millions of air molecules and gas atoms on the outside of the device to do its intended job of eliminating static charges near the device.

Richard Hull