Progress on Component Evaluation for Nuclear Explosion Monitoring

The Ground-Based Nuclear Explosion Monitoring Research and Development (GNEM R&D) program at Sandia National Laboratories (SNL) is regarded as the primary center for unbiased expertise in testing and evaluation of geophysical sensors and instrumentation for nuclear explosion monitoring. We had four main areas of interest to make progress on this year; this report will cover the advances made in these areas. First is the continued development and research of the three-component coherence technique of Sleeman et al. (2006). We have reverted back to synthetic testing to develop a firm understanding of the arithmetic limitations in processing to recover small value estimates of noise relative to large input signals. We explored the effects of digital quantization of the analog signal, as well as the limitations of the technique in the presence of high signal-to-noise input signals. The second area of interest is the upgrade of our suite of software used to analyze sensors and digitizer data (e.g., to calculate noise floor, time-tag accuracy). This past year has allowed us time to develop the new data model and relevant meta-architecture, proto-type existing algorithms in MATLAB with validation against existing tool sets, and develop sets of reusable modules (e.g., waveform editing tools and test description). Our third area of concentration over the past year focused on testing new components for both Provisional Technical Secretariat and the Air Force Technical Applications Center (AFTAC). Characterization reports were produced for two infrasound sensors, Chaparral Physics model 2.5 low-gain and the Inter-Mountain Labs model SS avalanche sensor as well as one data logger, Geotech Smart24. For the infrasound sensors tested, the test results allow us to conclude that both sensors had sufficiently quiet noise floor to be at or below the Acoustic low-noise model from 0.1 to 7 Hz, which make these sensors suitable to explosion monitoring. The characterization report on the Smart 24 documented meeting requirements for an International Monitoring System site. The final area of focus for the component evaluation (CE) project has been the maintenance and upgrade of our seismic and infrasound test-beds. Recent additions have included additional reference sensors for monitoring environmental conditions during infrasound testing as well as exploring the necessary requirements needed for an infrasound test chamber. This work directly impacts the Ground-Based Nuclear Explosion Monitoring mission by providing a facility, equipment, and personnel to give the operational monitoring agencies confidence in deployed instrumentation and capability for mission success. 2008 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies