Gordon Watts: Down Under

Yesterday was an amazingly clear day. Mt. Blanc, much like Mt. Rainier in Seattle, doesn't come out often. But it did yesterday:

But the really cool stuff was underground. ATLAS will be 100m below the ground. They have already constructed the cavern where it will be installed -- and an access shaft.

There is a movie of how ATLAS will be built. I definately recommend looking at it. The music is pretty bad, but you really get an appreciation for the complex job putting this experiment together is going to be!

This experiment has been in the planning and construction phase for almost 20 years. It is a huge relief to actually see it coming together as a real experiment in the pit!

The whole experiment will have to be lowered through this hole:

The ATLAS experiment is 100m long, and 40m by 40m! So, it has to be lowered down one bit at a time. We took a tour down to the pit. Here is that access shaft viewed from the cavern:

Those pipes coming down contain all sorts of services. This is the generic word for cooling, liquid He, cables, etc.

Just outside the cavern is the tunnel that contains the LHC accelerator. This is a 27 km long tunnel. The picture below shows the straight section just before the accelerator enters the ATLAS cavern:

When the accelerator is finished this area (and the long straight section at the back of the picture) will be filled with large magnets and pipes. They have a very cool trolley -- which you can see going by in the picture -- designed to carry the dipole magnets to their installation point. The machine runs by tracking a white line painted on the floor. How cool is that!?

The interior of the cavern is huge -- and getting smaller:

In the foreground of that image you see an installed muon torroid. This is a huge super-conducting magnet (the actual magnets are inside those red-striped pipes). At the back of the picture is a blue circle -- that is where the accelerator (from the picture above) will enter the cavern. The platform that is to the right of the muon torroid will eventually be removed, and central tracking and calorimetry will be placed there:

That is a shot from the other end of the cavern -- the large circular shaped object at the end is part of the calorimeter. Andy, a previou sstudent of mine, works on this at Columbia, actually. The group included Aran, who works with me, and Henry, another prof at UW who has done a lot to help build the forward muon chambers for ATLAS:

The construction hasn't been without problems. The muon torroids had a lot of trouble operating at first and threatened to tie up the whole installation schedule. And after the first part of the calorimeter was installed water dripped on it from a huge rain storm (the above ground building wasn't sealed too well).

Update: Fixed 27km diameter -> 27km circumference (!!)