Advanced Light Source (ALS) synchrotron for producing intense X-rays used to determine the structures of proteins at Lawrence Berkeley Laboratory, USA. A synchrotron accelerates electrons to very near the velocity of light. The electrons are confined in a circular tunnel by powerful magnets, and emit strong X-rays at high velocities. The X-rays are directed through crystals of proteins. This causes the X-rays to be scattered in a pattern that relates to the three- dimensional structure of the protein being analysed. Study of the structure and function of proteins (proteomics) provides information on how organisms work.