The LBNL Scintillator Research Group, formerly part of the Material Sciences Division, has joined the Nuclear Science Division. This move creates new opportunities for the development of novel radiation detection systems for a range of applications from basic science to nuclear security and medical imaging.
The detection of ionizing radiation underpins many applications that cover a large number of fields that span from the medical, to security inspection and non-destructive testing, to nuclear non-proliferation and emergency response, and to High Energy Physics. Many of these technologies rely on the capability of a group of materials, called scintillators, to efficiently convert the ionizing radiation into UV or visible light that can be more easily detected and analyzed. No single scintillator is, however, able to efficiently interact with all types of ionizing radiation, leading to the development of a large number of different materials tailored for each specific application. The discovery and the optimization of scintillators is still a thriving research field, as new needs arise.
The Scintillator Research Group at LBL has been active in inorganic scintillator research for over thirty years, building an almost unique laboratory in which all aspects of scintillator research can be tackled: from materials synthesis and growth into single crystals, to the characterization of their luminescence and scintillation properties. Over the past 15 years the Group discovered over 22 new scintillating materials. The Group is able to grow single crystals, Fig. 1, through a variety of methods (from Czochralski to Bridgman-Stokbarger and micro-Pulling Down) on both oxide- and halide-based scintillators. Optical, luminescence and scintillation properties of the obtained materials are investigated with a variety of methods (from photo- and radioluminescence both in steady state and time resolved (Fig. 2) manner, to pulse height spectra with gamma ray sources and thermally stimulated luminescence) in order to qualify these materials.
Primary interests of the Group include the discovery of new scintillators, the optimization of scintillator properties through suitable chemical addition/modification of their composition, fundamental physic phenomena underlying the scintillation process itself including the role of defects, and synthesis strategies. Although the Group focus has been on inorganic scintillators, it recently expanded also to water-based liquid scintillators as well as organic/inorganic composites.
The addition of the Scintillator Research Group strengthens NSD’s existing capabilities in radiation detector development and compliments the longstanding expertise in semiconductor development.
Federico Moretti and Weronika Wolszczak contributed to this article. Dr. Moretti is the PI of the Scintillator Research Group and Dr. Wolszczak is a Postdoctoral Researcher.
Figure 1: a polished piece of Cs2LiLaBr6:Ce (CLLB) single crystal grown by Bridgman Stockbarger.
Figure 2: Scintillation decay profile as a function of the temperature of a newly developed Tl2La0.95Ce0.05Cl5 single crystal measured with a table-top light-excited x-ray tube working at 40 kVp. The system has an instrument response function of about 100 ps. Measurements were performed in the 15-310 K. These scintillation decays allow to clarify how much charge carrier transport toward the luminescence centers is affected by the temperature. The curves have been shifted along the ordinate axis for clarity.