On the geiger counter side, you might be able to talk to your local school or college as they often have small sources of radiation for physics classes, and geiger counters too, so you could calibrate.

Sell the idea to the head of computing as an example of an embedded real time system...

Actually i thought about asking at the university, but i first must get to know the professors...

Here are some pics, how i imagined that the device would look like:

If i choose the mini version, i will have to make it like Cray did with their modules http://en.wikipedia.org/wiki/File:Cray-2_module_side_view.jpg.