train experiment

The biggest challenge to me seems that you would need a lot of space to allow the source to travel that speed towards the scatterer without slamming into the scatterer and destroying it. However if you use a circular motion at that speed you don’t have this issue. Now there will be a certain time interval where the source will have the correct relative speed with respect to the scatterer. A cyclotron is the first thing I can think of to accomplish this. Possibly with a monochromator to ensure correct wavelength and block parasitic sources.