April 17, 2012
SLAC physicist Tim Nelson examines the Silicon Tracking and Vertexing Detector, a new type of particle detector that can not only capture the tracks of particles resulting from a collision, but locate their vertices as well - in other words, where they first appear after the collision.
After this photograph was taken, the detector was carefully packed into its crate to be shipped to Thomas Jefferson National Accelerator Facility, in Newport News, VA, where it will become the centerpiece of the Heavy Photon Search (HPS). The HPS experiment will shoot electrons at a sheet of tungsten foil, and the detector will look for electron-positron pairs created during the collisions that seem to spring into being some distance from the foil. That may indicate that a "heavy" or dark matter photon was created first and traveled some distance before decaying into the electron-positron pair.
Physicists hunt for dark forces, Nature News