Now that's a neat toy! How beefy of a source was it? 1 uCi sources are readily available and safe to handle, but Co-60 sources powerful enough to be "self-protecting" exist (used in industry for sterilization, and in medicine for cancer treatment).
Don't think I ever knew how much "power" the Co60 source had.
It was a large (around 12 inches) lead lined steel cube, and it had a remote control "shutter" that would expose or cover the source. There was some sort of elaborate lead shielding in it where shield material overlapped to prevent any "line of sight" leakage.
I was scared to death of the thing... I handed the Prof. the chips with a note as to how much to irradiate them and scurried off in the other direction.
I want nothing to do with anything shorter wavelength than UV...

Edit to add: Years ago I was an engineer at a medical device manufacturer. We used ethylene oxide to sterilize the lots.
The ETO (ethylene oxide) was an explosive compound when pressurized and in liquid form. So, the ETO we used was called 88/12 because it was 88% ETO and 12% freon to render it "safer".
The ETO came as large gas cylinders on a pallette, all strapped together and connected to a common manifold. Since the ETO and freon had different density, it was supposed to be agitated (mixed) once in a while.
Being on a pallette and all tied together, it was obviously impossible to mix. So we flirted with explosive disaster on a daily basis. Thankfully my office was nowhere near the sterilizer area.
The point here is (I'm getting to it) the company decided to look into gamma sterilization. Knowing how slipshod they were with the ETO, I said "If they start doing gamma I'm outta here". Well, they eventually did go to gamma, but I left there before then for other reasons.