radiological materials and on nuclear materials production and usage. From May 2007 to May 2010, Dr. Wacker was detailed to the U.S. Department of Energy (DOE) in Washington, DC, where he served as the chief scientist on the Nuclear Materials Information Program. In his role he advised the DOE and other U.S. government agencies and departments on issues relating to nuclear materials and nuclear forensics. Since returning to PNNL in May 2010, he has continued advising the DOE on issues that include nuclear material analysis, sample archives, and data libraries, as well as assisting at the interagency level in the development of policy-level requirements for nuclear forensics. Prior to May 2007, Dr. Wacker managed research and development programs at PNNL that developed and applied nuclear detection and analysis techniques for the DOE and other U.S. government departments and agencies. From 1993 to 2004, Dr. Wacker managed an analytical laboratory at PNNL that performs nuclear material analyses in support of environmental analysis, treaty verification, and other nuclear safeguards activities. Dr. Wacker earned a Ph.D. in planetary sciences from the University of Arizona and a S.B. in physics from the Massachusetts Institute of Technology.