Yesterday the cyclotron’s vacuum chamber slid between the poles of our massive magnet for the first time. This moment was rather emotional, since these two main components of the cyclotron have never before touched. Now, more than ever before, this giant mass of metal is beginning to resemble a particle accelerator.
However, while the union of these two components was beautiful, it wasn’t without it’s problems! Most noticeably, the chamber did not initially fit between the pole pieces. In the design of the rail system that holds the chamber, I allowed 1/8th of an inch of space for a slick teflon surface on the rails. However, during the time crunch this summer, this piece was never added! After a heart-stopping moment of panic as the chamber stubbornly refused to fit between the poles, we resolved the problem. The chamber is now (temporarily) boosted up by two 1/8” pieces of steel that will supply the required height. Once this change was made, the chamber slid smoothly into place.
After the chamber was in, I went to work attaching the vacuum pumping stack to the bottom of the chamber. Here I faced a new problem; the vacuum pump cart was 3” too short to allow it to connect to the chamber! This was not unexpected; the concrete blocks that support the magnet were found on short notice and are a bit bigger than I would have liked. As a temporary fix, the vacuum pump is now supported on several thick pieces of wood rather than the wheels of its cart
After this problem was resolved, I turned on the pumps and watched as, for the first time, the cyclotron’s vacuum system pumped down the chamber. I definitely had my fingers crossed for this test! Any mistakes on my part as I assembled the chamber this summer could have led to contamination inside the chamber or even full blown leaks. However, to my relief, my handiwork seemed to hold and the chamber reached 5x10^-5 Torr; reasonably close to it’s design pressure. Since I didn’t use a normally essential component of the vacuum stack for this test (the LN2 cold trap) I am confident we will be able to reach our pressure goals without modifications.
Now that the chamber is pumping down, we can begin to run initial test with the ion source to prepare it for a hopeful attempt at beam within the next couple weeks.