Nerine Cherepy

Researcher

Materials Science Division

Lawrence Livermore National Laboratory

Development of New Plastic Scintillators and their Integration into Detectors and Imaging Systems

Organic scintillators are deployed widely for Homeland Security and Non-Proliferation missions, as well as used in Nuclear Physics experiments and for Environmental Monitoring. Organic scintillators are based on aromatic molecules, in the form of liquids, plastics and single crystals. The fundamental scintillator physics of organics involves ionization, exciton formation, energy transfer and luminescence. In particular, the excited electronic states in the organic scintillator may be manipulated by compositional modifications to enhance or diminish Fӧrster and Dexter transport of singlets and triplets, respectively. Efforts to develop new functionalities in organic scintillators have included (1) loading with high-Z elements or nanoparticles, to improve gamma stopping and provide gamma spectroscopy, (2) loading with thermal neutron reactive elements, such as lithium, for neutron detection, (3) modifying the host to enhance Dexter transport for particle discrimination based on pulse shape or minimizing Dexter transport to eliminate delayed luminescence, and (4) use of spin-orbit coupling (triplet-harvesting) fluors for high light yield. This presentation will review organic scintillation mechanisms, performance of several new plastic scintillators for gamma detection and spectroscopy, as well as neutron detection and neutron radiography.

Biography:

Nerine Cherepy earned a Ph.D. in Physical Chemistry from the University of California, Berkeley, utilizing laser spectroscopy to study energy and electron transfer. After postdoctoral work at the University of California, Santa Cruz on ultrafast laser spectroscopy, she joined Lawrence Livermore National Laboratory. Since 2005, she has worked on the development new light-emitting materials, including single crystals, transparent ceramics and plastics, for various uses in ionizing radiation detection, new imaging screens and lighting phosphors. She has been collaborating with Professor Qibing Pei (UCLA) for several years on plastic scintillator development. She has two R&D 100 awards, 15 awarded patents, more than 100 published papers, and she is a co-recipient of DHS’s Award for Excellence in Scintillator Discovery. She is a Senior Member of IEEE and SPIE and a recipient of the Lawrence Livermore National Laboratory Mid-Career Award.