ARI-MA: Fabrication of Solid-State Large Area Thermal Neutron Detectors at a Low Cost

Rensselaer Polytechnic Institute, Troy NY

Investigators

Abstract

1348269 (Danon). Detection of nuclear materials such as U and Pu is often accomplished by utilizing their natural or induced neutron emission. Such systems typically use thermal neutron detectors inside a plastic moderator. In order to achieve high detection efficiency He-3 or BF-3 filled thermal neutron detectors are utilized; these detectors require high voltage bias for operation, which complicates the system when many detectors are used in one system. In addition He-3 detectors are bulky and do not fit well for portable applications. A better type of detector would be an inexpensive solid-state detector that can be massively produced like any other computer chips. If such a detector does not require a bias for operation, could be produced with small or large surface area, and has a low gamma sensitivity and fast response, it will be the ideal low-cost detector for future neutron detection systems. Such detector was developed at Rensselaer Polytechnic Institute with demonstrated area of 8 cm2 (with single commercial preamplifier) and measured efficiency of 30% for 0.0253 eV neutrons. This project focuses on improvements of the fabrication process to utilize wet etching of Si (110), electrophoretic deposition of boron nanoparticles, and a design of compact integrated electronic readout. These improvements will reduce the production cost significantly, while improving the performance due to deeper silicon etching. The end result is targeted to be a low cost solid-state thermal neutron detector that is suitable and ready for use in many DNDO related applications. Intellectual merit includes development of new low-cost boron nanoparticle deposition methods to replace the LPCVD process. It also includes wet etching method with large aspect ratio; a low cost alternative to currently used Bosch process. In order to significantly improve the overall efficiency further, multiple device wafers are stacked together before interfacing with the compact integrated electronic readout. Additional contribution is education of students in the area of nuclear detector development that includes radiation interaction with matter and solid- state detector fabrication. The broader impact of this proposal is the development of a novel type of high efficiency self-powered solid-state neutron detector with a low production cost. The development in device fabrication will result in a new type of charged particle detectors based on solar-cell technology. In addition to homeland security applications, these technologies have applications in neutron dosimetry and monitoring used in the nuclear industry and research.