The Atlas is a multi-purpose 4pi detector, where more than 3000 physicists are working on. A very nice description can be found here. It's very cool, and strongly recommend to visit to briefly learn the Atlas detector.
The Atlas (and CMS) detector has superb capability to discover new particles, thanks to the high energy (sqrt(s) = 14 TeV in its design value, and currently sqrt(s) = 7 TeV) of LHC. If Higgs boson exists as an elementary particle (this means that the mass of Higgs boson is ligheter than approximately 1 TeV), we should be able to discover it. If Supersymmetry (SUSY) is the hidden symmetry, SUSY particle should be generated and detected with only a few fb^-1 of data. SUSY particle is a strong candidate of the dark matter. If that's the case, the most preferred parameter space (in SUSY model) can be easily scanned again with very small statistics.
Our Atlas group at Osaka is aiming for a discovery of Higgs boson and SUSY particles, and a study of their properties, especially for the Yukawa coupling to b-quark. For this purpose, b-jet identification (b-tag) plays a very important role in the analyses. We are working on, therefore, b-tag related tasks both in software and hardware.