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Segmentation of the Outer
Contact on
Dr. Ethan L Hull,
Dr.
DOE Grant No. DE-FG02-05ER84157
Amount: $99,840
Segmented germanium detector
arrays are needed by the DOE for the characterization of low-level radioactive
samples. In addition, the same detector
arrays could perform important fundamental physics measurements, including the
search for rare-events like neutrinoless double-beta decay. However, because of their complexity, these
segmented coaxial detectors are expensive and available only after relatively
long lead times. Improved fabrication
techniques would greatly reduce costs and improve the availability of these segmented
detectors for the low-level counting community.
Therefore, this project will experimentally investigate alternative
techniques for making segmented contacts on p-type coaxial germanium detectors,
which would be a much cheaper alternative to the segmented n-type coaxial
detectors currently proposed. However,
the difficulties associated with the segmentation of conventional thick
lithium-diffused contacts must be addressed.
Phase I will evaluate amorphous germanium contacts for the
hole-injection barrier on small planar test detectors. By making many detectors in rapid succession,
the best fabrication parameters will be determined and reconciled with
theory. To demonstrate the viability of
the fabrication technique, a p-type pseudo-coaxial detector having 8 segments
will be fabricated. By the end of Phase
II, the best fabrication technique for making segmented p-type coaxial
detectors will be determined.
Commercial Applications and Other Benefits as described by the awardee: The new germanium-detector technology should enable better detector performance at lower cost. In large low-background arrays, these detectors should find use in the assessment of low-activity radioactive sources of national security and environmental importance. In addition, the same detector arrays will take pure science to new levels of sensitivity in the Majorana search for neutrinoless double-beta decay. Other potential areas of importance to the DOE and the nation include nuclear nonproliferation, medical imaging, and x-ray detectors.