Nondestructive Characterization
Institute (NCI)

Harry Martz

As director of the Nondestructive Characterization Institute, Harry Martz is a world-recognized leader in the field of Non-Destructive Characterization (NDC) where his work addresses the research, development, and application of imaging modalities to NDC. He and his team focus on imaging at nanometer resolution, imaging objects with small and large cross-sections, imaging in the presence of high atomic materials and generating quantitative images. Harry’s efforts have led to the establishment of numerous NDC facilities at LLNL where, for over 25 years, NDC applications have included weapons, fusion targets, and conventional and homemade explosives.

Harry earned his PhD in Nuclear and Inorganic Chemistry from Florida State University. He has authored or coauthored about 300 technical papers and is coauthor of two book chapters plus a textbook on Industrial X-ray Imaging. He has serviced on numerous National Academy of Sciences committees and panels. Among his awards are an R&D 100 Award in Waste Inspection Tomography for Nondestructive Assay (2000) and Best Paper given for “Assay of Contained Waste Using Active and Passive Computed Tomography,” by the American Nuclear Society (1999).

Joe Tringe

Joe Tringe is the Director of LLNL’s Nondestructive Evaluation (NDE) Portfolio, with responsibilities spanning the Strategic Deterrence, Global Security and Engineering Directorates.  From 2016 to 2024, as NDE group leader in Engineering’s Materials Engineering Division, Joe guided a group of over 40 engineers and technicians, focused on characterizing a wide range of complex materials, structures, devices and systems. From 2003 to 2016 Joe was a staff scientist in the Physical and Life Sciences Directorate where he synthesized and characterized devices and materials with novel electrical, optical and molecular transport properties. Prior to joining LLNL in 2003 he led a group in the Air Force Research Laboratory Space Vehicles Directorate, which created and characterized radiation- and defect-tolerant electronic materials, devices and circuits for satellites.

Joe earned his PhD in Materials Engineering at Stanford University and has authored more than thirty-five peer-reviewed publications and five U.S. patents.

Katie Harke

Kathryn (Katie) Harke is a staff scientist in the Nondestructive Evaluation Group. At LLNL, Katie completed two years as a postdoctoral researcher in the Nondestructive Evaluation Group and became a staff member in 2021. Katie led a team to develop the 3-Ring Flash X-ray system, which can take a 3D X-ray movie of dynamic events and can field up to 1.5 lbs of TNT equivalent. Her field of interest is dynamic X-ray radiography at a range of scales, from small scale gas gun work at the Dynamic Compression Sector, to mid-scale work with high explosives utilizing flash X-ray radiography, to large-scale MeV systems like the Scorpius accelerator at the Nevada National Security Site.  

Katie’s graduate work focused on the study of materials in extreme conditions. She received her PhD in physics from the University of Alabama at Birmingham.

Peer-Timo Bremer

Peer-Timo Bremer holds a shared appointment at LLNL's Center for Applied Scientific Computing (CASC), focusing on large-scale data analysis and visualization, and at the University of Utah, serving as Associate Director for Research of the Center for Extreme Data Management Analysis and Visualization. His research interests include large-scale machine learning, data analysis, visualization, medical image analysis, topology, volume modeling, and virtual reality.

Peer-Timo is the co-Principal Investigator of several projects, including a Department of Energy project that seeks to apply high performance computing to accelerate new treatments for traumatic brain injury. He also is the co-PI for LLNL initiatives in cognitive computing, applying advanced computing to biological research, high-dimensional sampling, and variable precision computing, among others. Peer-Timo joined LLNL in 2006. Prior to that, he was a post-doctoral research associate at the University of Illinois, Urbana-Champaign. He received a Ph.D. in computer science in from the University of California, Davis, and an M.S. and B.S. in mathematics/computer science from the Leipniz University in Germany.

Nerine Cherepy

Nerine Cherepy works on the development new light-emitting materials, including single crystals, transparent ceramics and plastics, for various uses in ionizing radiation detection, new imaging screens, lighting phosphors and laser gain media. These efforts involve device integration of new light-emitting materials for gamma spectroscopy, X-ray and neutron imaging, as well as lighting and laser applications. She has been awarded 17 patents and more than 150 published papers in the area of materials development.

Nerine earned a Ph.D. in physical chemistry from the University of California, Berkeley. After postdoctoral work at the University of California, Santa Cruz, she joined Lawrence Livermore National Laboratory in 2005.

Sabrina DePiero

As the Associate Program Leader for Explosives Detection and Transportation Security within Global Security E Program, Sabrina DePiero develops and maintains programs that mitigate threats to aviation security, critical infrastructure, and other assets of national security interest. As the Group Leader for the Energetic Materials Formulation and Testing Group within the Materials Sciences Division, she is responsible for supervising a group of experimentalists to support functions at the High Explosives Application Facility (HEAF) and S300 Chemistry Area including formulations, pilot scale synthesis, small-scale safety testing, and materials characterization and testing. Sabrina also currently leads explosives activities including formulation and characterization of homemade explosives for the Livermore Explosives Detection Program (LEDP).

Prior to joining LLNL in 2006, Sabrina spent five years at The Clorox Company and two years in the pharmaceutical industry doing product and process development. Sabrina has a degree in chemical engineering from the University of California at Berkeley.

Allison Wright

Allison Wright is a Nondestructive Evaluation Engineer in the LLNL NDE group. She specializes in ultrasound inspection and is the Operations Manager for a new, state of the art, LLNL NDE research facility. This building has a unique breadth of NDE capabilities and is intended to serve as a collaboration space between LLNL and industry and universities.  

Prior to joining LLNL, Allison worked for 14 years in aircraft manufacturing in research & development of NDE for composite inspections supporting both commercial and defense platforms.  

Allison is an active volunteer with Society of Women Engineers (SWE), enjoys STEM and NDE outreach, and has held leadership roles at all levels of the organization. In 2016, she received the SWE Distinguished New Engineer Award. After completing a degree in aerospace engineering, Allison earned her MS in operations management at Friends University. She is the holder of two patents. 

Saptarshi Mukherjee

Saptarshi Mukherjee joined LLNL as a postdoctoral researcher and is currently working as an Applied Electromagnetics Research Scientist. Saptarshi’s research interests include nondestructive evaluation methods in advanced manufacturing, computational geosciences, imaging and inverse problems, and high-power microwave devices.

Saptarshi has authored 3 patents and over 20 technical papers. He is currently serving as an American Society for Nondestructive Testing (ASNT) mentor, committee member of ASNT research and engineering councils, and current chair of the ASNT Golden Gate Section. He has served as the chair of the Electromagnetic Nondestructive Evaluation workshop at LLNL and a session chair for 8 international conferences. Prior to joining LLNL, Saptarshi earned his PhD in electrical engineering from Michigan State University.

David Stobbe

David Stobbe is a Group Lead for Ultrasonics and Sensors in Nondestructive Evaluation (Materials Engineering Division) at LLNL. His work focuses on ultrasound techniques as they pertain to material characterization and defect detection, and his primary research interests include laser-based ultrasound and solid mechanics. Prior to joining LLNL, David worked as an expert witness in the field of mechanical engineering. As a licensed Professional Engineer, he testified in trials and depositions, in multiple state and federal courts, regarding the root cause failure mode of mechanical components and systems. He also previously worked as an opto-mechanical engineer at Northrop Grumman Corporation where he focused on structural and thermodynamic computational modeling and chaired the analysis tools implementation committee. 

Currently, David develops novel optical ultrasound systems at LLNL to serve current and future mission critical needs. His work has resulted in numerous high impact journal publications and conference presentations.