Elemental mapping of planetary surfaces using gamma-ray spectroscopy
The gamma rays escaping from a planet can be used to map the concentrations of various elements in its surface. In a planet, the high-energy particles in the galactic cosmic rays induce a cascade of particles that includes many neutrons. The {gamma} rays are made by the nuclear excitations induced by these cosmic-ray particles and their secondaries (especially capture or inelastic-scattering reactions induced by neutrons) and decay of the naturally-occurring radioelements. After a short history of planetary {gamma}-ray spectroscopy and its applications, the {gamma}-ray spectrometer planned for the Mars Observer mission is presented. The results of laboratory experiments that simulate the cosmic-ray bombardments of planetary surfaces or measure cross sections for the production of {gamma} rays and the status of the theoretical calculations for the processes that make and transport neutrons and {gamma} rays will be reviewed. The emphasis here is on studies of Mars and on new ideas, concepts, and problems that have arisen over the last decade, such as Doppler broadening and peaks from neutron scattering with germanium nuclei in a high-resolution {gamma}-ray spectrometer. 31 refs., 1 fig., 1 tab.
- Research Organization:
- Los Alamos National Lab., NM (USA)
- Sponsoring Organization:
- DOD; NASA
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6416802
- Report Number(s):
- LA-UR-90-3503; CONF-901057--4; ON: DE91001877
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
651100 -- Nuclear Physics-- Experimental Techniques-- (1980-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALUMINIUM
BARYON REACTIONS
COSMIC RADIATION
DOPPLER BROADENING
ELEMENTS
GAMMA SPECTRA
GAMMA SPECTROSCOPY
GE SEMICONDUCTOR DETECTORS
HADRON REACTIONS
IONIZING RADIATIONS
LINE BROADENING
MAPPING
MARS PLANET
MEASURING INSTRUMENTS
METALS
NEUTRON REACTIONS
NUCLEAR REACTIONS
NUCLEON REACTIONS
PLANETS
RADIATION DETECTORS
RADIATIONS
SCATTERING
SEMICONDUCTOR DETECTORS
SPECTRA
SPECTROSCOPY
SURFACES
TOPOLOGICAL MAPPING
TRANSFORMATIONS