These facilities are generally free to use, and are open to scientists from all over the world, usually through the submission and evaluation of research proposals.
The light sources are synchrotron or x-ray free electron laser facilities that provide users with x-ray beams for a variety of scattering, spectroscopy, and imaging experiments.
These facilities accommodate tens of beamlines running in parallel.
The super-computing facilities are made available to the users to perform high intensity calculations.
As of November 2019, four of the top ten super computers worldwide were hosted by a national user facility [2] ( Summit, Sierra, Trinity and Lassen.)