I want to detect when a Scalextric car passes a certain point on the track

I've seen this dome with a light source above the track and something set into the track to detect when the car passes

I understand this is done using a light sensitive transistor set into the track and connected to the joystick port.

My questions:

Is a light sensitive transistor called something else because I can't track any down?

How does it connect to the joystick port?



Thanks