Highly Segmented Hyper-Pure Germanium Detectors
Result of NP research:
Gamma Ray Energy Tracking Array project and Majorana double beta decay project
Application currently being supported by:
DOE-NP, Defense Programs, Navy Research Lab, NIH, NASA, PNNL, and LANL.
Impact/benefit to spin-off field:
Higher sensitivity for small tumors and better characterization in Emission Tomography. Cancer treatments could benefit from more accurate activity uptake and reliable dosimetry for optimized cancer treatment planning and improved capabilities in detecting, locating and characterizing of radioactive material. Tracking detector arrays in space will bring higher efficiency and pointing capability to more rapidly survey gamma-ray sources in the cosmos. Provides improved rejection of backgrounds in measurements of very low-level radioisotopes of interest for monitoring of clandestine nuclear activities.
High resolution germanium tracking detector arrays, being developed at LBNL, is envisioned to track every gamma ray detected, providing complete energy and direction of travel information, and providing orders-of-magnitude increased sensitivity for gamma-ray detection. Investigators at LLNL are collaborating with LBNL scientists to develop algorithms to determine gamma-ray interaction positions in the germanium, and are investigating the use of these detectors to efficiently assay waste drums that might contain uranium or plutonium. This directional information would enable the localization and imaging of the radioactive sources, and improving the sensitivity of detecting weak and remote sources.
These new segmented germanium arrays will provide a number of new and improved capabilities in detecting, locating and characterizing of radioactive material. At distances comparable to the size of the radioactive material, images of the material could be obtained. It will give the size, shape and the spatial distribution of the radioactive material. At larger distance, the direction of gamma rays can be determined. Using two detectors or two measurements with adequate separation, we can determine the location of the material. The high efficiency of the array combined with the reduced background due to the direction discrimination, will provide higher sensitivity- smaller amount of material can be detected at larger distance in a shorter time. Such detectors can be installed at port of entry such as airports, seaports and broader crossings, to detect and characterize radioactive material brought in by terrorist. Mounted on airplane, it can quickly map a larger area and locate hidden material. Above, the Cryo3 module is a hand-held high resolution germanium spectrometer developed at LLNL, in collaboration with scientists at LBNL.