If UDH is really produced and it require some kind of stimulation then I am afraid that there might be nothing visible in Cloud Chamber. Then it could lead to a wrong conclusion.
I think that I have to find if it is really sensitive to EM pulses. If yes then I was very lucky that my detector actually is producing these pulses. Maybe even configured voltage is playing a role. I will check if a sparks from high voltage can do something interesting.
In any way replication is required as fast as possible.