This circuit uses a diode as a radiation sensor. The operational ones are old because the publication is from the 80's, but modern low voltage equivalents can be tested.
This circuit, with printed circuit board included, is from a Radio Electronics magazine from July...
In the figure we show how to excite a CMOS port by interrupting light on a Darlington...
We found this circuit in an old documentation, but it uses components that are still common in our...