Large volume Ring-Contact HPGe Detectors (RCD) for low-background counting arrays and radiopurity-assay

DOE Nuclear Physics missions include the ongoing search for rare processes including neutrinoless double-beta decay (NLDBD). Major DOE efforts include funding of the MAJORANA Demonstrator project, and potential funding of a ton-scale LEGEND-1000 project. These DOE science programs, and other more common applications of germanium detectors will benefit from the existence of the new Ring Contact Detectors (RCDs) being developed here. To populate large low-background germanium detector arrays, the very largest mass individual germanium-detector element is desired to provide the lowest background level per gram of germanium in the array. The RCD detector stands to be the largest mass and lowest background candidate for these detector arrays. The RCD detector concept is being experimentally developed by this SBIR project. During Phase I, the critical semiconductor-processing steps for RCD fabrication were developed. A prototype RCD0 detector was successfully fabricated and tested to demonstrate that the RCD concept is technically viable. Phase II will see the experimental development, manufacture, and demonstration of successively larger size and mass prototype RCDs. The optimum size and mass detectors made during Phase II will become the basis for early beta-product RCD sales and further adaptation for alternative commercial products. The RCD concept will naturally contribute to other DOE security-related fields including nuclear weapons non-proliferation, treaty verification, nuclear-explosion monitoring, nuclear materials holdup, nuclear safeguards and diagnostics. However, the compact Fulcrum-RCD field-portable detector system will be extremely useful to programs outside DOE conducting all manner of radiation-detection missions.