All graduate students in the physics department are invited only to work on a PhD - there is no formal application for a master's degree. However, if you make it through the first year of the PhD program and satisfy all the requirements, you may leave the program at any point with a master's. These requirements currently are: pass qualifying exam, pass 36 units of classes with a GPA of 3.0 & above.
If you choose to leave the program with a master's, you must fill out some paperwork with the department graduate coordinator.