Shane Larson is a physicist at Utah State University, and also a LEGO hobbyist. So it's very appropriate that he built a scene of the target from a particle accelerator. He's even included a photo and diagram of the real thing so you can compare. A particle accelerator takes charged particles (like protons) and propel them at great velocities at a target. When they crash into the target, they break apart into even smaller building blocks, that can then be studied by the physicists to learn about the fundamental structure of matter.
BTW, this is a vignette, or a scene built on a small base. For more vignette LEGO creations, see VignetteBricks.