The newest accelerators are the very pinnacle of scientific discovery, and it is moving seriously fast. Only a hundred years ago we were discovering that an atom was more than a microscopic blob and now we're smashing them to find things like dimensions past the four of space-time and new particles whose names continue to make me burst out laughing.
CERN is responsible for all this, the biggest particle labs in the world. Right now they have just about finished the LHC (Large Hadron Collider) which is yet another variation of the popular synchrotron accelerator and will start testing in summer 08, or as soon as its been cooled to -273.15 degrees Celsius.
It is situated on the French Swiss border in a place that previously housed the LEP collider. CERN has decreased the dimensions of its investigations to beyond atomic while increasing the scale and expense of its equipment. They will be using in excess of 7 trill volts to smash protons together at the highest energies ever, to prove the existence of the higgs boson (which may gives matter its mass). It is the last puzzle piece to the elusive standard theory, and everyone is wondering nervously if they will instead create micro black holes (this has caused some controversy as some physicists think these experiments are capable of destroying the Earth. At least it will he Switzerland first- heh heh).
Dark matter (currently hypothetical matter that doesn't reflect EM radiation, but has to exist if the universe behaves as it does) is also on the must find' list.
They are trying to take us back to the first 10-35 seconds after the big bang. However, these protons they're planning on smashing are made of quarks and gluons which would make it hard to measure resultant energy levels with great accuracy, because its unclear what the levels in each quark are before the collision.
That is why the tandem project- ILC -is investigating electron on positron collision, because they are fundamental particles rather than composites (a positron is the antimatter version of the electron. It has the same mass as an electron but with a positive charge of 1. They are commonly produced by nuclear decay, but the ones that are used are created from electrons while in the collider because of the difficulty of storing antimatter).
This new accelerator is right now at the stage of being thought over by a lot of guys with crazy hair drinking coffee. They are thinking of reverting back to the old linear model accelerator used in the past (not used today because they have to be very long) because as an electron speeds around a ring, it radiates away its energy (synchrotron radiation) making it progressively harder to accelerate, and they want them to be going fast!( 0.999997828 times the speed of light. Nothing can move faster than the speed of light because as their kinetic energy increases, the extra energy is not turned into velocity but mass, making it even harder to accelerate).
The more you want to accelerate the electrons the longer the lineac has to be, so this one is going to be more than 30km long, the longest ever built. So long that they'll have to take the curvature of the earth into account during construction. The machine uses 250 billion Volts (less than the LHC because the electrons have less mass than bulky protons meaning less energy is needed to accelerate them). Six separate experiments will be run on the LHC using different technologies.
Finding the answers to our existence is nice and all, but particle accelerators are used in everyday life as well. They are used to dry paint on drinks cans, and allow us to jellify our brains on a daily basis with that miraculous invention of TV.
So much money spent on accelerators, but the rewards will be worth it in the long run. What price can you put on knowledge? 3 billion Euros for the LHC to be precise...so far.