Masters or for BS? Just sounds like more of a bachelors since they didn't say anything about an assistantship or TA/RA salary (And it's addressed to you for an HS instead of a University).
If that's the case the term you are looking for is Major.
Just teasing you a bit. Congrats man! The only physics I know is Geophysics, but if you ever want to talk Earth and Oil I'm around.
:$ SIGMA