I wanted to try using a Darlington pair with an ion chamber (small tube) to detect alpha particles, as this site explains: http://www.techlib.com/science/ion.html Before I order any components, I was wanting to throw something together with some normal transistors I already have. I was curious what qualities make a transistor more or less desirable to use as a Darlington pair. I have some 6027, 3904, 2222A, 4401, and 2907A transistors. Which would be best? Worst? Why? Thanks for any insight.