Monitoring Sources of Nuclear Radiation in Space 1980-1984 Observations. Revision
Memorandum rept. Apr 1980-Jan 1985
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
This report provides details of SMMs observations of the seven RORSATS launched from 1980 through 1984. Estimates are obtained of the relative power of the reactors from integral gamma-ray intensities measured at distances 400 km. The average intensities from the seven satellites, after correcting for distance of separation, are consistent with each other to within 30. In contrast, the rate of distant detections of positrons increased with time over the four-year period. The rate of detections was about 0.2day in 1980 and 0.7 day in 1984. This increasing rate is due to the decreasing atmospheric density above a few hundred km in the transition from maximum to minimum solar activity. The positron storage time in the geomagnetic field is expected to increase with decreasing density. A composite gamma-ray spectrum created from a summation of close-approach sightings of the seven RORSATS will be presented. It is not possible to obtain a unique interpretation of this spectrum. One relatively simple model of the gamma-ray spectrum emitted from the RORSATS which fits the data reasonably well includes the following components a fission continuum from 235U and neutron capture lines from molybdenum embedded within tens of gsq cm of material two unresolved lines near 500 keV attributed to a line at 511 keV from positron-annihilation and to a line near 477 keV from boron.
- Nuclear Instrumentation
- Radioactivity, Radioactive Wastes and Fission Products
- Unmanned Spacecraft