I applied in-person. The process took 1 day. I interviewed at Brookhaven National Laboratory (Upton, NY) in Feb 2016
Interview
Five interviewers in different area such as applied math, physics, compter engineerings for two hours.
Mainly technical questions related with math and science (physics).
High Performacne Computing (HPC) would be important.
After the interview, there was background check and three recommendation letters are requested.