SBIR-STTR Award

The Geiger-Muller (GM) tube is a standard instrument for dose rate measurements on the nuclear battlefield, yet the technology is expensive and is being phased out of commercial dosimeters. This will result in the military being the sole consumer, effectively making the technology obsolete. To mitigate against obsolescence, a cost-effective nuclear-survivable technology is to be developed. Advances in scintillation materials and photodetectors have resulted in a broad selection of components that may serve as a direct replacement to the GM tube. Even though the dark current increases when exposed to radiation, the silicon photomultiplier (SiPM) is a high-gain photodetector readily available at a low cost. The proposed research plan studies on mitigating radiation damage in SiPMs or provide an alternative photodetector technology. The scintillation-based detector can provide dose rate measurements down to background levels, while at the highest rates up to 100 Gy/hr advanced semiconductor materials, such as commercially available diodes made from GaN. The proposed effort will assess the nuclear survivability of these wide bandgap semiconductors. As cost is a critical factor, this project will study the manufacturing methods and materials to provide a cost-effective nuclear-survivable gamma-ray dose rate sensor.

In the condition of a nuclear event, it is critical that warfighters and first responders are equipped with active dosimeters and dose rate meters. These tools can be made from scintillation-based detector systems that require a high performance photodetector. The silicon photomultiplier is a compact photodetector that would be ideal for such a detector system, yet their performance suffers from thermal effects, where the gain (breakdown voltage) and noise floor (dark current) have a dependence on temperature. The radiation tolerance of silicon photomultipliers will likely not meet requirements for nuclear survivability. Some III-V semiconductor materials can intrinsically provide a higher radiation tolerance than silicon as well as a reduction in the underlying temperature effects. The project will explore the development of a solid-state photomultiplier, an array of Geiger photodiodes, using III-V materials, and will characterize their nuclear survivability.