The capstone project for attaining your doctorate is your dissertation defense.
You can update your dissertation reading committee by submitting a new form
Once you schedule a date and time, contact the Graduate Program Coordinator to schedule a room, publicize your defense (you provide the title and abstract), and to see if they can help with setup/break down. Please note that faculty and graduate students should help the presenter with coffee/tea, and setup/breakdown for food. Physics staff are beleaguered as it is, let's not add to their workload. See the GradWiki entry on "Coffee for Events"
You need to bring your title page to your defense. Get "wet ink" signatures on that form and submit it by the deadline. That, plus a good draft submitted to Proquest (https://graddiv.ucsc.edu/current-students/pdfs/dissertation-thesis-guidelines.pdf) by the deadline and you will be henceforth known as "Dr." (I can tell you from personal experience that it is awesome and it continues to pay dividends). You can find more information here.
Upload your dissertation defense materials here, it'll help the next generation of graduate students.