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Title: The processing of enriched germanium for the Majorana Demonstrator and R&D for a next generation double-beta decay experiment

The Majorana Demonstrator is an array of point-contact Ge detectors fabricated from Ge isotopically enriched to 88% in 76Ge to search for neutrinoless double beta decay. The processing of Ge for germanium detectors is a well-known technology. However, because of the high cost of Ge enriched in 76Ge special procedures were required to maximize the yield of detector mass and to minimize exposure to cosmic rays. These procedures include careful accounting for the material; shielding it to reduce cosmogenic generation of radioactive isotopes; and development of special reprocessing techniques for contaminated solid germanium, shavings, grindings, acid etchant and cutting fluids from detector fabrication. Processing procedures were developed that resulted in a total yield in detector mass of 70%. However, none of the acid-etch solution and only 50% of the cutting fluids from detector fabrication were reprocessed. Had they been processed, the projections for the recovery yield would be between 80% and 85%. Maximizing yield is critical to justify a possible future ton-scale experiment. A process for recovery of germanium from the acid-etch solution was developed with yield of about 90%. All material was shielded or stored underground whenever possible to minimize the formation of 68Ge by cosmic rays, which contributesmore » background in the double-beta decay region of interest and cannot be removed by zone refinement and crystal growth. Formation of 68Ge was reduced by a significant factor over that in natural abundance detectors not protected from cosmic rays.« less
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Publication Date:
Report Number(s):
Journal ID: ISSN 0168-9002; TRN: US1703243
Grant/Contract Number:
AC52-06NA25396; AC02-05CH11231; FG02-97ER41041; FG02-97ER41033; FG02-97ER41042,; SC0012612; FG02-10ER41715; SC0010254; FG02-97ER41020; PHY-0919270, PHY-1003940, PHY-0855314; PHY-1202950; MRI 0923142; PHY-1307204; PHY-1003399; 15-02-02919; AC05-00OR22725
Published Article
Journal Name:
Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Journal Information:
Journal Volume: 877; Journal Issue: C; Journal ID: ISSN 0168-9002
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); National Science Foundation (NSF); Russian Foundation for Basic Research
Contributing Orgs:
Majorana Collaboration; GERDA Collaboration
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Atomic and Nuclear Physics; Double-beta decay; Neutrino physics; Instrumentation
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1402647; OSTI ID: 1419471; OSTI ID: 1454382