Why are the hall's in bio-dome shapes?
The answer to your question is the answer to many questions... money. The shape of our experimental halls was that which could do the job and spend the least amount of money. There are several reasons for this that you won't quite understand unless you have taken geometry. If you need to enclose a certain amount of AREA, but have to pay for the LENGTH of wall you use, you want to build whatever type of building will enclose that AREA with the shortest LENGTH of wall. It just so happens a circle encloses the most AREA for a given amount of wall LENGTH.
The dome shape of the roof is the strongest, so it needs the least amount of material to support its load. The dome also has to support the crane inside attached to it and the deep pile of dirt on top of it. You see domes on all sort of buildings and tanks because it takes the pushing down force of its own weight and whatever it is also supporting and transfers it to the walls. To keep our walls from bending outward we have a tension ring that pulls the top of the wall in. Luckily these forces balance and our walls don't go in or out.
Putting up the domes was one of the coolest things done here. If you think about it, which one is put on first? The tension ring pulling in or the dome pushing out? We actually had to go back and forth, putting some of the dome concrete and then some of the tension ring and then back for more dome concrete. The tension ring was installed by putting a huge spool of cable on the back of a truck and lifting the truck onto the partially completed dome. The cable was then attached to the wall and the truck started driving around the dome all day. Sort of your own version of the NASCAR truck series.
It also helps that two of our Halls, A and C, have spectrometers that pivot around a central post, making the circular shape ideal. Actually, the idea for the domes was that they be sort of like water tanks. We (humans in general) build a lot of water tanks so we thought it would be easy to find expertise in building the domes. It worked, they were relatively cheap and are very sturdy.
Brian Kross, Chief Detector Engineer (Other answers by Brian Kross)