Search NASA⌕ Search

SEARCH · Search NASA

Results for “Isotopic composition”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Mean isotopic composition of cosmic rays with 12 less than Z less than or equal to 26 at 2.7 to 3.0 GV

Results are presented from a high-altitude balloon flight in September 1972 near 3-GV geomagnetic cutoff. The detector is a combination of ionization chambers and a Lucite Cerenkov counter with a charge resolution of 0.34 charge units. Following the technique described by Lund et al. (1971), use is made of the geomagnetic rigidity cutoff and measured momentum-per-nucleon spectra of individual elements to determine values of A/Z for even Z elements of 16 less than or equal to Z less than or equal to 26 relative to A/Z of silicon.

Maehl, R. C.↗
NASA NTRS1975

The isotopic composition of cosmic rays with 5 is less than or equal to z which is less than or equal to 26

Results obtained from a high altitude balloon flight from Thompson, Canada in August, 1973 are reported. The instrument consisted of a spark chamber, a Lucite Gerenkov counter and thirteen layers of scintillators. For heavy particles the Cerenkov-range method of analysis was used to determine the mass of particles energetic enough to produce a Cerenkov signal and then stop in the layered scintillators. The data appear to be consistent with current cosmic-ray propagation models. Using a simple exponential path length propagation model this data is extrapolated to the cosmic-ray source and some implications of the data are discussed as to the nature of the source.

Fisher, A. J.↗
NASA NTRS1976

Isotopic composition of nitrogen - Implications for the past history of Mars' atmosphere

Models are presented for the past history of nitrogen on Mars, based on Viking measurements showing that the atmosphere is enriched in N-15. The enrichment is attributed to selective escape, with fast atoms formed in the exosphere by electron impact dissociation of N2 and by dissociative recombination of N2(+). The initial partial pressure of N2 should have been at least as large as several millibars and could have been as large as 30 millibars if surface processes were to represent an important sink for atmospheric HNO2 and HNO3.

Mcelroy, M. B.↗