Low-Cost SSPM-Based Digital Radiation Monitor

81146S06 Many contaminated facilities throughout the DOE complex will reside in a safe storage or surveillance and maintenance (S&M) mode until such time that funding resources are available to perform decontamination and demolition. Long-term monitoring systems are required to ensure against a contaminant release and to provide rapid response in the case of such an event. Also, new or improved monitors or sensors are needed to record contaminant levels that would expose workers during deactivation and decontamination activities. This project will apply the solid-state photomultiplier (SSPM) detector concept to produce a sensor capable of long-term functionality. Complimentary metal oxide semiconductor (CMOS) fabrication technology will provide a low-cost, process-controlled production method; scintillation detection will provide a proven, high-efficiency nuclear detection method at a low cost. Phase I designed and fabricated SSPM array chips and coupled them to various scintillation materials to demonstrate their performance. Experiments were conducted to determine a configuration that maintains low cost with maximum sensitivity. An early prototype achieved an energy resolution of 22% for 511-keV photons detected with LYSO. Phase II will optimize the design of the scintillation detector and CMOS solid-state photomultiplier device, and integrate the necessary components to construct a ¿rate-meter-on-a-chip.¿ The prototype device will be modified to increase the detection efficiency by more than a factor of four. Commercial Applications and Other Benefits as described by the awardee: The technology should be appropriate for monitoring DOE legacy sites while providing state-of-the-art spectroscopic information. In addition, a low-cost digital rate-meter should be of use to companies and national laboratories that have a need for dosimeters that can provide improved monitoring, reduced liability, and improved record keeping ability. Also, nuclear, high energy, and atomic physics experiments that use scintillator readout or direct detection of light should benefit from improved SSPM¿s.