I am super happy that my classmate Yen, who happens to work at ITP as well, heard about my project and gave me a beautiful big natural stone that he kept in his office . Very likely it is granite and therefore a good source for natural radiation / random numbers.
So last night I sat down and did a few experiments measuring the amount of decaying particles with and without a stone close to the geiger-counter. I conducted 3 test rows, so three times with the stone, three times without the stone.
Here are the results measured over the time of 3 minutes each:
The stone from Yen's office seems to be slightly radioactive, around 15 - 20% compared to "normal" conditions that mainly detect gamma rays from cosmic radiation. It is still very low compared to carbon-monoxide detectors, big granite kitchen countertops, old watch luminescent hands, which emit many more decaying particles over this amount of time.
installation prototype setup
I decided to do a quick run to test parts of the setup. Here a solenoid knocks the random particle decay from inside the stone that gets detected by the geiger counter back into the stone - the heart of the stone is talking to its audience:
So far so good - tomorrow I have to test the setup powered entirely with two solar panels - let's hope the sun is out and the panels can generate enough current to power the entire installation!