Here are the major projects ongoing at the LHC:
ALICE (A Large Ion Collider Experiment @ CERN): By smashing particles together, scientists can recreate the first few milliseconds after the Big Bang, illuminating the early history of the universe. A detector 52 feet (16 meters) high and 85 feet (261 m) long enables scientists to study what's known as quark-gluon plasma. The researchers collide heavy ions, liberating their quarks and gluons (quarks are the constituent part of protons, which are held together by gluons). It takes a machine like the LHC to separate these atomic particles and study them individually.
ATLAS (A Toroidal LHC Apparatus): This is the experiment that observed a Higgs in July. But ATLAS's work isn't done. The LHC, and the ATLAS detector, are currently in shutdown mode, preparing for an energy increase. When LHC starts up again after 2013, the atom smasher will be able to fling protons at each other at 14 teraelectronvolts (TeV), double its previous 7 TeV.
ATLAS has a broad mission. It's a tool that can search for extra dimensions of space and supersymmetry, the idea that every known particle has a "superpartner particle," an important component of string theory. Supersymmetry would, in turn, help elucidate dark energy, which may exist in the vacuum of space and be responsible for the acceleration of the universe's expansion. ATLAS is also part of the search for dark matter, a mysterious form of matter that may make up more than 95 percent of the universe's total matter density, but which is virtually unknown. [Whoa! The Coolest Little Particles in Nature]
CMS (Compact Muon Solenoid): Like ATLAS, CMS is a jack-of-all trades. The detector is meant to explore the same questions about the origins of the universe and the fundamentals of matter.