This graphic can explain very clearly, although it’s a little old. The result is that constraints today are even tighter though, so for these purposes it’s stil

This graphic can explain very clearly, although it’s a little old. The result is that constraints today are even tighter though, so for these purposes it’s still useful. https://4.bp.blogspot.com/-UN8jPwzj2qI/V9hRVCG1HBI/AAAAAAAACBA/cvuTent6YO4QarFX7XUYgrg6sDinHdglwCK4B/s1600/DirectDetection.png https://4.bp.blogspot.com/-UN8jPwzj2qI/V9hRVCG1HBI/AAAAAAAAC...