Sorry that I did not post all of the parameters. The ball will pass by about 20mm from the sensor at most ever 2 seconds. The sensor will be mounted inside a machine that has an opening in it so a little light will be coming from the outside. The sensor I am planning to use an off the shelf sensor where I can just connect the wires to a motherboard rather than solder components together to create it. I am planning to use a diffuse reflective optical/photoelectric sensor as it does not require a reflector, just the light reflected from the ball. I am pretty sure I do not need a diffuse sensor with background suppression as the reflection from the inside case of the machine will be very low and not reflected right back.
I do not think that focusing on the sensor is putting the cart before the horse at all. Rather it is the most important part to focus on as one must first find a sensor that operates at a certain detection distance (I am choosing 30mm max), operates on the diffuse reflection method and has a response time that can detect a ball moving at a speed that puts it in front of the sensor for only 1.84ms. All else is secondary. I have sourced about a dozen sensors and they seem to all operate with response times of 0.8-5ms. None were in nanoseconds. An engineer at one of the top sensor companies, Banner, who sell 12,000 different sensors, told me that the faster the response time the better and that 1.5ms, the response time of one sensor I was looking at in their lineup, is cutting it a bit to close to 1.84ms. Also I found out that the response time is also the time the sensor needs to not be active in order to detect the next ball.
By the way, Banner does not have a single sensor whose response time is measured in nanoseconds. The fastest is 0.15ms.
I found my solution. Now comes the testing as specs are one thing. Real world testing is another.