Mechanically Cooled Large-Volume Germanium Detector Systems for Nuclear Explosion Monitoring
Abstract
Compact maintenance-free mechanical cooling systems are being developed to operate large volume (approx. 570 cm(3), approx. 3 kg, 140 % or larger) germanium detectors for field applications. A new generation of domestically produced Stirling-cycle mechanical coolers provide the basis for this evolution. When properly instrumented, these systems can cool the very largest volume germanium detectors with no maintenance or liquid nitrogen requirements. The user can leave these systems unplugged on the shelf until needed. The maintenance-free operating lifetime of these detector systems will exceed 5 years. These features are necessary for remote long-duration liquid-nitrogen free deployment of large-volume germanium gamma-ray detector systems for nuclear explosion monitoring. The Radionuclide Aerosol Sampler/Analyzer (RASA) will greatly benefit from the availability of such detector systems by eliminating the need for liquid nitrogen at RASA sites while still allowing the very largest available germanium detectors to be utilized for the highest sensitivity measurements. To reliably provide such systems, the basic technical fundamentals are being investigated: temperature, vacuum, and vibration. A RASA cryostat and detector have been developed and fabricated. The cryostat has been tested and verified to cool a very large (as large as 10-cm long by 10-cm diameter) detector to temperatures as low as 50 degrees Kelvin. The system is free of microphonic noise with the cooler operating at full power. The lower detector operating temperature, coupled with robust detector fabrication technology, provides a detector system that will operate reliably for a very long time (5+ years).
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2007
- Accession Number
- ADA519831
Entities
People
- Bruce E. Suttle
- Craig E. Aalseth
- Ethan L. Hull
- Harry S. Miley
- James R. Lathrop
- Peggy L. Mann
- Richard H. Pehl
- Ronnie B. Mashburn
- Theodore W. Bowyer
- Todd W. Hossbach
Organizations
- Pacific Northwest National Laboratory